Cyclopentenone derivatives for cancer therapy

Preparation of Substituted Furfuryl Alcohols of the Formula (3)

Furyl-(3,4,5-trimethoxyphenol)methanol

Magnesium (1.68 gm, 70 mmol) was taken in three neck R.B. flask equipped with condensor, 100 ml ether followed by dibromoethane (9.5 gm, 51.02 mmol) were added with stirring at 0° C. under nitrogen atmosphere. Stirring was continued until all the magnesium reacted, then the ether was removed under vacuum until a slurry was formed. (A). In another single neck R.B. flask furan (4.76 gm, 70 mmol) in tetra-hydrofuran (100 ml) was cooled with ice-salt mixture, n-butyl lithium (2M, 35 ml, 70 mmol) was added dropwise, and the mixture was stirred at 0° C. for 45 min. (B) Furyllithium thus prepared in flask (B) was added to cold mixture in (A) through cannula, stirred at 0° C. for 5 min, brought to room temperature and stirred at room temperature for 1.5 hrs; then cooled to −20° C. (dry ice and CCl 4 ). Substituted benzaldehyde (51.02 mmol) in tetra-hydrofuran (50 ml) was added and stirred at −20° C. for 4 hr (monitored by TLC). After completion of reaction the mixture was quenched with saturated ammonium chloride solution. The mixture was allowed to warm to room temperature. Solvent was removed under reduced pressure and residue extracted with ethyl acetate. The organic layer was washed with water followed by brine, dried over sodium sulfate and concentrated to dryness under reduced pressure using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluents) to collect pure compounds of the formula of structure 3 (yield, 93%).

Spectral data of furyl-(3,4,5-trimethoxyphenyl)methanol:

1 H NMR(CDCl 3 +CCl 4 ): δ 2.72 (bs, 1H), 3.84 (s, 9H), 5.75 (bs, 1H), 6.15(d, J=6 Hz, 1H), 6.27–6.32 (m, 1H), 6.66(d, J=2 Hz, 2H) 7.40(bs, 1H).

Mass (m/e): 264 (M + , 80), 247 (60), 233 (12), 214 (15), 189 (20), 169 (70) 161 (25), 95 (100)

Preparation of 2-(3,4,5-trimethoxyphenyl)-4-hydroxy-cyclopent-2-enones

A solution of aryl furfuryl alcohol i.e. compound of the formula of structure 3 wherein R 1 and R 5 are H and R 2 –R 4 are OCH 3 (25 gm, 94.69 mmol) and ZnCl 2 (51.26 gm, 378.7 mmol) in dioxan (30 ml) and water (206 ml) was refluxed for 24 h at which time TLC analysis indicated the complete disappearance of starting material. The mixture was brought to room temperature, acidified to pH 1 with dilute HCl and extracted with ethyl acetate. The organic layer was washed with water, followed by brine and dried over sodium sulphate. The organic layer was concentrated under reduced pressure using rotary evaporator to collect the required 2-(3,4,5-trimethoxyphenyl)-4-hydroxy-cyclopent-2-en-1-one (21.25 gm, 85%).

Spectral data:

1 H NMR(CDCl 3 +CCl 4 ): δ 2.52 (d, J=18 Hz, 1H), 3.00 (dd, J=18 Hz and 6 Hz, 1H), 3.86 (s, 3H), 3.89 (s, 6H), 5.00–5.10 (m, 1H), 6.98 (s, 2H), 7.58 (d, 1H). Mass (m/e): 264 (M + , 100), 249 (57), 233 (10), 221 (22), 205 (32), 189 (15), 177 (20), 161 (40).

Preparation of Tert-butyldimethylsilyl Derivatives

A solution of 2-aryl-4-hydroxy-cyclopent-2-en-1-one of formula (4) (8.7 mmol) in dry dichloromethane (30 ml) was stirred at 0° C. under inert atmosphere (maintained by using nitrogen or argon gas filled in balloon), a solution of tert-butyl dimethylsilyl chloride (1.5 gm, 9.95 mmol) and dimethylamino pyridine (0.194 gm, 1.5 g mmol) in dichloromethane (10 ml) was added drop wise and stirred at the same temperature for 15 min. Then triethylamine (1.77 ml, 12.7 mmol) was added and mixture was warmed to room temperature and stirred further for 3 h (monitored by TLC). The reaction mixture was filtered through whatman filter paper, dichloromethane was removed under reduced pressure and extracted with chloroform. The organic layer was washed with water, followed by brine, dried over sodium sulphate and concentrated to dryness under reduced pressure using rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluent) to give the title derivatives.

Spectral data of 2-(3,4,5-trimethoxyphenyl)-4-tert.-butyldimethylsilyoxy-cyclopent-2-en-1-one:

1 H NMR(CDCl 3 +CCl 4 ): δ 0.16 (s, 3H), 0.17 (s, 3H), 0.94 (s, 9H), 2.47 (d, J=18 Hz, 1H), 2.92 (dd, J=18 Hz and 6 Hz, 1H), 3.85 (s, 3H), 3.90 (s, 6H), 495–5.05 (m, 1H), 6.96 (s, 2H), 7.45 (d, 1H).

Mass (m/e): 378 (M + , 100), 363 (10), 321 (15), 290 (40), 219 (70).

Preparation of 4-acetoxy-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one

A solution of 2-(3,4,5-trimethoxyphenyl)-4-hydroxy-cyclopent-2-en-1-one (3 gm, 11.36 mmol) in dichloromethane (30 ml) was cooled to 0° C. using ice-salt bath. To the cold solution dry pyridine (1.70 gm, 1.73 ml; 26.0 mmol) was added and stirred at 0° C. for 10 min. To the stirred solution, acetic anhydride (1.63 gm, 1.50 ml, 16.0 mmol) was added dropwise while maintaining the temperature below 0° C. The reaction mixture was stirred at room temperature for 15 h (monitored by TLC) then quenched by adding cold, dilute hydrochloric acid. The organic layer was washed three times with water, 10% sodium bicarbonate solution and finally brine. The organic layer was dried over sodium sulfate and concentrated to dryness under reduced pressure using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluent) to collect the pure 4-acetoxy-2-(3,4,5-trimethoxy-phenyl)-cyclopent-2-en-1-one (2.56 gm, 73.47%).

Spectral data:

1 H NMR(CDCl 3 +CCl 4 ): δ 2.08 (s, 3H), 2.54 (d, J=18 Hz, 1H), 3.00 (dd, J=18 Hz and 6 Hz, 1H), 3.82 (s, 3H), 3.84 (s, 6H), 5.80–5.90 (m, 1H), 6.96 (s, 2H), 7.59 (d, J=4 Hz, 1H)

Mass (m/e): 306 (M + , 100), 264 (14), 247 (34), 231 (8), 219 (51).

Heck Reaction of Aryl Iodides with Cyclopentenone

A mixture of of p-iodo anisole (3.71 gm, 15.87 mmol), 2-(3,4,5-trimethoxyphenyl)-4-hydroxy-cyclopent-2-enone (7.93 mmol),), palladium acetate (0.230 gm, 1.026 mmol), triphenyl phosphine, (0.400 gm, 1.52 mmol), potassium carbonate (2.20 gm, 15.86 mmol), and catalytic amount of tetrabutylammonium bromide (0.030 gm) in degassed acetonitrile was refluxed for 36 h. Then the reaction mixture was cooled to room temperature, and acetonitrile was removed under reduced pressure using a rotary evaporator. The residue was acidified with dilute HCl and then extracted with chloroform. The organic layer was washed with water followed by brine, dried over sodium sulfate and concentrated to dryness under reduced pressure, using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluent) to collect pure products of the formula of structure (7).

Spectral data of compound of the formula of structure (7)

1 H NMR(CDCl 3 +CCl 4 ): δ 2.65 (d, J=18 Hz, 1H), 3.11 (dd, J=18 Hz and 8 Hz, 1H), 3.72 (s, 6H), 3.83 (s, 3H), 3.86 (s, 3H), 5.45–5.50 (m, 1H), 6.46 (s, 2H), 6.87 (d, J=10 Hz, 2H), 7.41 (d, J=10 Hz, 2H).

Mass (m/e): 370 (M + , 100), 355 (19), 262 (32), 231 (20), 219 (18), 177 (30), 163 (27), 135 (25).

Preparation of Compound of Formula of Structure (10)

A mixture of p-iodo anisole (3.71 gm, 15.87 mmol), 2-(3,4,5-trimethoxyphenyl)-4-ter-butyldimethylsilyoxy-cyclopent-2-enone (7.93 mmol),), palladium acetate (0.230 gm, 1.026 mmol), triphenyl phosphine, (0.400 gm, 1.52 mmol), potassium carbonate (2.20 gm, 15.86 mmol), and catalytic amount of tetrabutylammonium bromide (0.030 gm) in degassed acetonitrile was refluxed for 36 h. Then the reaction mixture was cooled to room temperature, and acetonitrile was removed under reduced pressure using a rotary evaporator. The residue was acidified with dilute HCl and then extracted with chloroform. The organic layer was washed with water followed by brine, dried over sodium sulfate and concentrated to dryness under reduced pressure, using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluent) to collect pure products of the formula of structure (10).

Spectral data of compound of the formula of structure (10):

1 H NMR(CDCl 3 +CCl 4 ): δ 0.05 (s, 3H), 0.09 (s, 3H), 0.80 (s, 9H), 2.57 (d, J=16 Hz, 1H), 3.02 (dd, J=16 Hz and 6 Hz, 1H), 3.69 (s, 6H), 3.82 (s, 3H), 3.84 (s, 3H), 5.30–5.40 (m, 1H), 6.44 (s, 2H), 6.82 (d, J=6 Hz, 2H), 7.27 (d, J=6 Hz, 2).

Mass (m/e): 484(M + , 5), 427 (30), 369 (32), 353 (100), 325 (61), 294 (47).

Preparation of Compound of Formula of Structure (11)

A mixture of iodobenzene (15.87 mmol), 2-(3,4,5-trimethoxyphenyl)-4-ter-butyldimethylsilyoxy-cyclopent-2-enone (7.93 mmol), palladium acetate (0.230 gm, 1.026 mmol), triphenyl phosphine, (0.400 gm, 1.52 mmol), potassium carbonate (2.20 gm, 15.86 mmol), and catalytic amount of tetrabutylammonium bromide (0.030 gm) in degassed acetonitrile was refluxed for 36 h. Then the reaction mixture was cooled to room temperature, and acetonitrile was removed under reduced pressure using a rotary evaporator. The residue was acidified with dilute HCl and then extracted with chloroform. The organic layer was washed with water followed by brine, dried over sodium sulfate and concentrated to dryness under reduced pressure, using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluent) to collect pure products of the formula of structure (11).

Spectral data of compound of the formula structure (11):

1 H NMR(CDCl 3 +CCl 4 ): δ −0.05 (s, 3H), 0.05 (s, 3H), 0.77 (s, 9H), 2.61 (d, J=18 Hz, 1H) 3.05 (dd, J=18 Hz and 6 Hz, 1H), 3.63 (s, 6H), 3.82 (s, 3H), 5.27–5.33 (m, 1H), 6.47 (s, 2H), 7.32 (bs, 5H).

Mass (m/e): 454 (M + , 28), 379 (100), 323 (28), 291 (27), 247 (92), 219 (66), 75(83).

Preparation of Compound of Formula of Structure (12)

A mixture of 3,5-dimethyl-4-methoxy-1-iodobenzene (15.87 mmol), 2-(3,4,5-trimethoxyphenyl)-4-ter-butyldimethylsilyoxy-cyclopent-2-enone (7.93 mmol),), palladium acetate (0.230 gm, 1.026 mmol), triphenyl phosphine, (0.400 gm, 1.52 mmol), potassium carbonate (2.20 gm, 15.86 mmol), and catalytic amount of tetrabutylammonium bromide (0.030 gm) in degassed acetonitrile was refluxed for 36 h. Then the reaction mixture was cooled to room temperature, and acetonitrile was removed under reduced pressure using a rotary evaporator. The residue was acidified with dilute HCl and then extracted with chloroform. The organic layer was washed with water followed by brine, dried over sodium sulfate and concentrated to dryness under reduced pressure, using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluent) to collect pure products of the formula of structure 12.

Spectral data of compound of the formula of structure 12:

1 H NMR(CDCl 3 +CCl 4 ): δ −0.01 (s, 3H), 0.07(s, 3H), 0.78(s, 9H), 2.20(s, 6H), 2.56(d, J=18 Hz, 1H) 3.01(dd, J=18 Hz and 6 Hz, 1H), 3.68(s, 6H), 3.70(s, 3H), 3.83(s, 3H), 5.20–5.30(m, 1H), 6.51(s, 2H), 6.97 (s, 2H).

Mass (m/e): 512 (M + , 18), 456 (38), 425 (16), 381 (51), 353 (15), 322 (13) 129(100).

Preparation of Compound of Formula of Structure 13

A mixture of 2,5-dimethoxy-1-iodobenzene (15.87 mmol), 2-(3,4,5-trimethoxyphenyl)-4-ter-butyldimethylsilyoxy-cyclopent-2-enone (7.93 mmol), palladium acetate (0.230 gm, 1.026 mmol), triphenyl phosphine, (0.400 gm, 1.52 mmol), potassium carbonate (2.20 gm, 15.86 mmol), and catalytic amount of tetrabutylammonium bromide (0.030 gm) in degassed acetonitrile was refluxed for 36 h. Then the reaction mixture was cooled to room temperature, and acetonitrile was removed under reduced pressure using a rotary evaporator. The residue was acidified with dilute HCl and then extracted with chloroform. The organic layer was washed with water followed by brine, dried over sodium sulfate and concentrated to dryness under reduced pressure, using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluent) to collect pure products of the formula of structure 13.

Spectral data of compound of the formula of structure 13:

1 H NMR(CDCl 3 +CCl 4 ): δ −0.19 (s, 3H),−0.04 (s, 3H), 0.74 (s, 9H), 2.55 (d, J=16 Hz, 1H), 3.02 (dd, J=16 Hz and 6 Hz, 1H), 3.63 (s, 6H), 3.65 (s, 3H), 3.69 (s, 3H), 3.78 (s, 3H), 5.25–5.38 (m, 1H), 6.45–6.72 (m, 3H), 6.75–6.96 (m, 2H).

Mass (m/e): 514 (M + , 71), 458 (87), 443 (30), 384 (40), 154 (70) 75 (100).

Example 10 describes a general method for deprotection of tert-butyldimethylsilyloxy group used in preparation of various compounds described in this specification. The compounds of the formula 8 and 9 are specific compounds obtained using this method from their corresponding TBS derivatives, i.e. compound 8 is obtained from compound 12 and compound 9 is obtained from compound 13.

Deprotection of Tert-butyldimethylsilyloxy Derivatives

A solution of protected 4-tert-butyldimethylsilyloxy-2,3-diarylcyclopent-2-enone (0.72 mmol) in acetic acid; tetrahydrofuran and water (3:1:1) was heated at 50° C. for 20 h (monitored by TLC). The reaction mixture was cooled to 0° C. and neutralized by sodium bicarbonate and extracted with chloroform. The organic layer was washed with water followed by brine and dried over sodium sulfate and filtered. The filtrate was concentrated to dryness under reduced pressure using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluent) to collect the 4-hydroxy-2,3-diarylcyclopentenone of the general formula of structure 6.

Spectral data of compounds of the formula of structure 8:

1 H NMR(CDCl 3 +CCl 4 ): δ 2.21 (s, 6H), 2.63 (d, J=18 Hz, 1H), 3.07 (dd, J=18 Hz and 6 Hz, 1H), 3.69 (s, 6H), 3.71 (s, 3H), 3.84 (s, 3H), 5.35–5.45 (m, 1H), 6.47 (s, 2H), 7.06 (s, 2H).

Mass (m/e): 398 (M + , 100), 367 (5), 262 (32), 247 (51), 231 (12), 177 (15), 149 (13).

Spectral data of compounds of the formula of structure 9:

1 H NMR(CDCl 3 +CCl 4 ): δ 2.63 (dd, J=18 Hz and 2 Hz, 1H), 3.06 (dd, J=18 Hz and 6 Hz, 1H), 3.59 (s, 3H), 3.64 (s, 6H), 3.71 (s, 3H), 3.80 (s, 3H), 5.35–5.50 (m, 1H), 6.45–6.75 (m, 3H), 6.84–7.00 (m, 2H).

Mass (m/e): 400 (M + , 19), 369 (3), 111 (82), 83 (52), 71 (67).

Preparation of Compound of the Formula of Structure 14

A solution of 2-(3,4,5-trimethoxyphenyl)-3-(4-methoxyphenyl)-4-hydroxy-cyclopent-2-en-1-one (0.235 gm, 0.63 mmol) in dichloromethane (20 ml) was cooled to 0° C. using ice-salt bath. To the cold solution dry pyridine (0.10 gm, 1.46.0 mmol) was added and stirred at 0° C. for 10 min. To the stirred solution, acetic anhydride (0.10 gm, 0.95 mmol) was added drop wise while maintaining the temperature below 0° C. The reaction mixture was stirred at room temperature for 15 h (monitored by TLC) then quenched by adding cold, dilute hydrochloric acid. The organic layer was washed three times with water, 10% sodium bicarbonate solution and finally brine. The organic layer was dried over sodium sulfate and concentrated to dryness under reduced pressure using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluent) to collect the pure 2-(3,4,5-trimethoxyphenyl)-3-(4-methoxyphenyl)-4-acetoxy-cyclopent-2-en-1-one (0.21 gm, 80.45%).

Spectral data:

1 H NMR(CDCl 3 +CCl 4 ): δ 2.01 (s, 3H), 2.52 (d, J=18 Hz, 1H), 3.15 (dd, J=18 Hz and 6 Hz, 1H), 3.71 (s, 6H), 3.81 (s, 3H), 3.85 (s, 3H), 6.40 (m, 1H), 6.44 (s, 2H), 6.81 (d, J=8 Hz, 2H), 7.26 (d, J=8 Hz, 2H).

Mass (m/e): 412 (M + , 100), 397 (8), 352 (13), 337 (17).

Preparation of Diketone of the Structure 15

A solution of pyridinium chlorochromate (0.300 gm) in dichloromethane (20 ml) was cooled to 0° C., stirred for 5 minutes, then a solution of 2,3-diaryl-4-hydroxy cyclopentenone of the formula 7, (0.200 gm, 0.54 mmol) in dichloromethane (5 ml) was added and stirred for 2 hours at room temperature (monitored by TLC). The reaction mixture was filtered through celite. The filtrate was washed with water followed by brine and dried over sodium sulfate, and concentrated to dryness under reduced pressure using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluents) to collect pure cyclopentenedione of the structure 15 (0.060 gm, 30.16%).

Spectral data:

1 H NMR(CDCl 3 +CCl 4 ): δ 3.17 (s, 2H), 3.69 (s, 6H), 3.83 (s, 3H), 3.88 (s, 3H), 6.63 (s, 2H), 6.88 (d, J=6 Hz, 2H), 7.38 (d, J=6 Hz, 2H).

Mass (m/e): 368 (M + , 100), 353 (30), 283 (23), 169 (20), 111 (46) 69 (70).

Preparation of Oxime of the Structure 16

A mixture of ketone of the formula 7 (0.100 gm, 0.20 mmol), hydroxyl amine hydrochloride (0.02 gm, 0.30 mmol) and sodium acetate (0.025 gm, 0.30 mmol) in ethanol (5 ml) was refluxed on water bath for 3 h. The reaction was monitored by TLC and after completion of reaction the solvent was removed under reduced pressure using a rotary evaporator. The residue was extracted with chloroform. The organic layer was washed with water followed by brine and dried over sodium sulfate and concentrated to dryness under reduced pressure using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluent) to collect pure oxime of the structure 16 (0.086 gm, 83.50%).

Spectral data:

1 H NMR(CDCl 3 +CCl 4 ): δ 2.80 (d, J=18 Hz, 1H), 3.36 (dd, J=18 Hz and 8 Hz, 1H), 3.73 (s, 6H), 3.79 (s, 3H), 3.87 (s, 3H), 5.30–5.40 (m, 1H), 6.47 (s, 2H), 6.80 (d, J=8 Hz, 2H), 7.26 (d, J=8 Hz, 2H).

Mass (m/e): 385 (M + , 100), 368 (40), 336 (12).

Preparation of Oxime of Structure 17 from Compound of Structure 16

A solution of pyridinium chlorochromate (0.080 gm) in dichloromethane (10 ml) was cooled to 0° C., stirred for 5 minutes, then a solution of 2,3-diaryl-4-hydroxy cyclopentenone of the formula 16, (0.075 gm, 0.19 mmol) in dichloromethane (5 ml) was added and stirred for 2 hours at room temperature (monitored by TLC). The reaction mixture was filtered through celite and the filtrate was washed with water followed by brine and dried over sodium sulfate, and concentrated to dryness under reduced pressure using rotary evaporator. The crude residue was purified by a column chromatography using silica gel (petroleum ether: acetone as eluents) to collect pure cyclopentenedione of the structure 17 (0.026 gm, 35%).

Spectral data compound of the structure 17:

1 H NMR(CDCl 3 +CCl 4 ): δ 3.41 (s, 2H), 3.69 (s, 6H), 3.80 (s, 3H), 3.89 (s, 3H), 6.58 (s, 2H), 6.83 (d, J=9 Hz, 2H), 7.24 (d, J=9 Hz, 2H), 8.60 (bs, 1H).

Mass (m/e): 384 (M + , 100), 367 (37), 336 (34), 307 (12).

Preparation of Oxime of the Structure 19

A mixture of ketone of the formula 10 (0.100 gm, 0.20 mmol), hydroxyl amine hydrochloride (0.02 gm, 0.30 mmol) and sodium acetate (0.025 gm, 0.30 mmol) in ethanol (5 ml) was refluxed on water bath for 3 h. The reaction was monitored by TLC and after completion of the reaction the solvent was removed under reduced pressure using rotary evaporator. The residue was extracted with chloroform, the organic layer was washed with water followed by brine and dried over sodium sulfate and concentrated to dryness under reduced pressure using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluent) to collect pure oxime of the structure 19 (0.086 gm, 83.50%).

Spectral data:

1 H NMR(CDCl 3 +CCl 4 ): δ −0.01 (s, 3H), 0.08 (s, 3H), 0.82 (s, 9H), 2.70 (d, J=18 Hz, 1H), 3.32 (dd, J=18 Hz and 6 Hz, 1H), 3.69 (s, 6H), 3.78 (s, 3H), 3.84 (s, 3H), 5.24–5.30 (m, 1H), 6.46 (s, 2H), 6.76 (d, J=9 Hz, 2H), 7.14 (d, J=9 Hz, 2H), 7.85 (bs, 1H).

Mass (m/e): 499 (M + , 68), 442 (67), 368 (100), 320 (12), 74 (60).

Preparation of Dioxime of the Structure 18

A mixture of diketone of the formula 15 (0.060 gm, 0.16 mmol), hydroxylamine hydrochloride (0.026 gm, 0.40 mmol) and sodium acetate (0.033 gm, 0.40 mmol) in ethanol (5 ml) was refluxed on a water bath for 3 hrs. (monitored by TLC). Then the solvent was removed under reduced pressure using a rotary evaporator and the residue obtained was extracted with chloroform. The organic layer was washed with water followed by brine and dried over sodium sulfate, concentrated to dryness under reduced pressure using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluent) to collect pure dioxime of the structure 18 (0.033 gm, 51.6%).

Spectral data:

1 H NMR(CDCl 3 +CCl 4 ): δ 3.42 (s, 2H), 3.47 (s, 6H), 3.61 (s, 3H), 3.64 (s, 3H), 6.36 (s, 2H), 6.60 (d, J=6 Hz, 2H), 7.06 (d, J=6 Hz, 2H).

Preparation of Compound of the Structure 20

A mixture of ketone of the formula 14 (0.100 gm, 0.24 mmol), hydroxylamine hydrochloride (0.023 gm, 0.36 mmol) and sodium acetate (0.03 gm, 0.36 mmol) in ethanol (5 ml) was refluxed on a water bath for 3 h. The reaction was monitored by TLC and after completion of reaction the solvent was removed under reduced pressure using a rotary evaporator. The residue was extracted with chloroform, the organic layer was washed with water followed by brine and dried over sodium sulfate and concentrated to dryness under reduced pressure using a rotary evaporator. The crude residue was purified by column chromatography using silica gel (petroleum ether: acetone as eluent) to collect pure oxime of the structure 20 (0.088 gm, 85.40%).

Spectral data of compound of structure 20:

1 H NMR(CDCl 3 +CCl 4 ): δ 2.02 (s, 3H), 2.72 (d, J=18 Hz, 1H), 3.40 (dd, J=18 Hz and 6 Hz, 1H), 3.72 (s, 6H), 3.78 (s, 3H), 3.87 (s, 3H), 6.25–6.35 (m, 1H), 6.46 (s, 2H), 6.75 (d, J=10 Hz, 2H), 7.12 (d, J=10 Hz, 2H).

Mass (m/e): 427 (M + , 100), 412 (7), 369 (47), 351 (25), 320 (31), 305 (7).

The compound of the formula of structure 21 was prepared from a compound of the formula of stru7cture 13 by using the same procedure as above.

Spectral data of compound of the formula of structure (21):

1 H NMR(CDCl 3 +CCl 4 ): δ −0.21 (s, 3H), −0.06 (s, 3H), 0.76 (s, 9H), 2.69 (d, J=18 Hz, 1H), 3.36 (dd, J=18 Hz and 6 Hz, 1H), 3.64 (s, 3H), 3.66 (s, 6H), 3.70 (s, 3H), 3.80 (s, 3H), 5.20–5.30 (m, 1H), 6.50–6.57 (m, 3H), 6.76 (bs, 2H), 7.99 (bs, 1H).

Mass (m/e): 529 (M + , 63), 512 (71), 472 (100), 398 (68), 75 (60).

Preparation of 5-tert-Butyldimethylsilyloxy-3-(4-methoxy-3-i-propoxyphenyl)-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one of the formula (56)

4-Iodo-2-i-propoxyanisole (1.94 g, 7.90 mmol) in dry tetrahydrofuran (10 ml) was stirred under nitrogen at −78° C. and n-butyl lithium (3.45 ml of 2.3 M solution, 7.90 mmol) was added dropwise. The reaction mixture was stirred at −78° C. for 1.5 h. 4-tert-Butyldimethylsilyloxy-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one (2.00 g, 5.29 mmol) in dry tetrahydrofuran (10 ml) was added and the reaction mixture was stirred at −78° C. for 12 h. It was then quenched with saturated ammonium chloride solution (30 ml), tetrahydrofuran was removed under reduced pressure, extracted with dichloromethane (3×50 ml), washed with water (2×20 ml) followed by brine (1×20 ml), dried (sodium sulfate), concentrated and purified by column chromatography over silica gel (eluent-8% acetone in pet ether) to afford the compound of the formula (4A) wherein R 1 =R 5 =R 6 =R 7 =R 10 =H, R 2 =R 3 =R 4 =R 8 =OMe, R 9 =Oi-Pr (1.28 g, 45%) as yellowish semisolid.

The above alcohol of the formula (4A) wherein R 1 =R 5 =R 6 =R 7 =R 10 =H, R 2 =R 3 =R 4 =R 8 =OMe, R 9 =Oi-Pr (0.50 g, 0.92 mmol) in dry dichloromethane (15 ml) was stirred with pyridinium dichromate (0.69 g, 1.83 mmol) under nitrogen at room temperature for 4 h. It was then filtered through celite (3.00 g), washed with dichloromethane (50 ml), concentrated and purified by column chromatography over silica gel (eluent-5% acetone in pet ether) to afford the title compound of the formula (56) (0.42 g, 79%).

Spectral data of compound of the formula of structure (56)

1 H NMR (CDCl 3 +CCl 4 ): δ 0.21 (s, 6H), 0.96 (s, 9H), 1.13 (d, J=6 Hz, 3H), 1.16 (d, J=6 Hz, 3H), 2.92(dd, J=18 Hz, and 6 Hz, 1H), 3.33 (dd, J=18 Hz and 6 Hz, 1H) 3.74 (s, 6H), 3.81 (s, 6H), 3.85 (s, 3H), 4.01–4.06 (m, 1H), 4.45–4.50 (m, 1H), 6.41 (s, 2H), 6.80 (d, J=8 Hz, 1H), 6.83 (d, J=2 Hz, 1H), 7.08 (dd, J=8 Hz and 2 Hz, 1H).

13 C NMR(CDCl 3 +CCl 4 ): δ −5.19, −4.42, 18.30, 21.61, 21.75, 25.76 (3C), 39.07, 55.61, 55.79 (2C), 60.46, 71.05, 106.33 (2C), 111.04, 115.71, 121.62, 127.21, 128.39, 135.78, 137.65, 146.51, 152.17, 153.42 (2C), 162.39, 204.77, 205.00

Preparation of O-tert-Butyldimethylsilyloxy-3-(4-methoxyphenyl)-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one of formula (52)

Magnesium turnings (0.19 g, 7.93 mmol) were taken in a 100 ml round bottom flask under nitrogen atmosphere. Dry tetrahydrofuran (25 ml) was added followed by dropwise addition of p-bromoanisole (1.48 g, 7.90 mmol). The reaction mixture was stirred at room temperature for 2 h by which time all the magnesium reacted to form 4-methoxyphenyl magnesium bromide. 4-tert-Butyldimethylsilyloxy-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one (2.00 g, 5.29 mmol) in dry tetrahydrofuran (15 ml) was added and stirred at room temperature for 2 h. It was then quenched with dil hydrochloric acid (25 ml), tetrahydrofuran was removed under reduced pressure, reaction mixture was extracted with ethyl acetate (3×25 ml), washed with water (2×25 ml), dried over sodium sulfate, concentrated and purified by column chromatography over silica gel (eluent-7% acetone in pet ether) to yield the alcohol of the formula (4A) wherein R 1 =R 5 =R 6 =R 7 =R 9 =R 10 =H, R 2 =R 3 =R 4 =R 8 =OMe (1.28 g, 52%).

The above alcohol of the formula (4A) wherein R 1 =R 5 =R 6 =R 7 =R 9 =R 10 =H, R 2 =R 3 =R 4 =R 8 =OMe (1.15 g, 2.36 mmol) was dissolved in dry dichloromethane (30 ml) and stirred under nitrogen with pyridinium dichromate (1.73 g, 7.38 mmol) under nitrogen at room temperature for 12 h. Workup as in example 1 and purification by column chromatography over silica gel (eluent-3% acetone in pet ether afforded the title compound of the formula (52) (0.52 g, 45%).

Spectral data of compound of the formula of structure (52)

1 H NMR (CDCl 3 +CCl 4 ): δ 0.23 (s, 6H), 0.97 (s, 9H), 2.94 (dd, J=16 Hz and 4 Hz, 1H), 3.30 (dd, J=16 Hz and 8 Hz, 1H), 3.74 (s, 6H), 3.81 (s, 3H), 3.85 (s, 3H), 4.45–4.52 (m, 1H), 6.44 (s, 2H), 6.80 (d, J=8 Hz, 2H), 7.35 (d, J=8 Hz, 2H)

Preparation of 5-tert-Butyldimethylsilyloxy-3-(4-thiomethylphenyl)-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one of formula (55)

4-Bromothioanisole (1.07 g, 5.28 mmol) and magnesium metal (0.12 g, 5.28 mmol) were placed in a 100 ml two-necked round bottom flask under argon atmosphere. Dry tetrahydrofuran (10 ml) was added and the mixture was stirred at room temperature for 2 h. It was then cooled to 0° C., 4-tert-butyldimethysilyloxy-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one (1.00 g, 2.64 mmol) in dry tetrahydrofuran (10 ml) was added dropwise, stirred at 0° C. for ½ h and then at room temperature for 2 h. The reaction was then quenched with saturated ammonium chloride solution (50 ml) and tetrahydrofuran was removed under reduced pressure. The residual reaction mixture was extracted with ethyl acetate (3×50 ml), washed with water (2×20 ml) followed by brine (10 ml), dried (sodium sulfate) and concentrated. Purification by column chromatography over silica gel (eluent-7% acetone in pet ether) afforded the compound of formula (4A) wherein R 1 =R 5 =R 6 =R 7 =R 9 =R 10 =H, R 2 =R 3 =R 4 =OMe, R 8 =SMe (0.95 g, 72%).

The above compound of formula (4A) wherein R 1 =R 5 =R 6 =R 7 =R 9 =R 10 =H, R 2 =R 3 =R 4 =OMe, R 8 =SMe (0.65 g, 1.29 mmol) in dry dichloromethane (10 ml) was cooled to 0° C., pyridinium dichromate (0.96 g, 2.5 mmol) was added, the mixture was stirred at the same temperature for 1 h and then stirred at room temperature for 10 h. It was then filtered through celite (2.00 g) and washed with dichloromethane (20 ml).The combined dichloromethane layer was washed with water (2×10 ml) followed by brine (5 ml), dried (sodium sulfate), concentrated and purified by column chromatography over silica gel (eluent-2–5% acetone in pet ether) to afford the compound of formula (55) (0.30 g, 46%).

Spectral data of compound of the formula of structure (55)

1 H NMR (CDCl 3 +CCl 4 ): δ 0.23 (s, 6H), 0.98 (s, 9H), 2.48 (s, 3H), 2.96 (dd, J=16 Hz and 4 Hz, 1H), 3.30 (dd, J=16 Hz and 6 Hz, 1H), 3.74 (s, 6H), 3.86 (s, 3H), 4.45–4.60 (m, 1H), 6.44 (s, 2H), 7.31 (d, J=8 Hz, 2H).

13 C NMR(CDCl 3 ): δ −5.23, −4.53, 14.70, 18.22, 25.69 (3C), 39.25, 55.83 (2C), 60.57, 72.84, 106.44 (2C), 125.12 (2C), 127.01, 128.57(2C), 131.11, 136.40, 137.80, 142.06, 153.16 (2C), 162.13, 204.92

Mass (m/z): 500 (M + )

Preparation of 5-Hydroxy-3-(3-chloro-4-methoxyphenyl)-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one of formula (67)

A mixture of magnesium turnings (0.31 g, 13.1 mmol), 2-chloro-4-bromoanisole (3.00 g, 13.5 mmol), 4-tert-butyldimethysilyloxy-2-(3,4,5-trimethoxy-phenyl)-cyclopent-2-en-1-one (2.58 g, 6.84 mmol) and dry tetrahydrofuran (35 ml) under nitrogen was stirred at room temperature for 4 h. Reaction was then quenched with dil hydrochloric acid (30 ml), tetrahydrofuran was removed under reduced pressure and the residual reaction mixture was extracted with ethyl acetate (3×35 ml), washed with water (2×20 ml) and dried over sodium sulfate. Concentration and purification by column chromatography over silica gel (eluent-6% acetone in pet ether) afforded the alcohol of the formula (4A)

wherein R 1 =R 5 =R 6 =R 7 =R 10 =H, R 2 =R 3 =R 4 =R 8 =OMe, R 9 =Cl (1.32 g, 37%).

A solution of the above alcohol of the formula (4A) wherein R 1 =R 5 =R 6 =R 7 =R 10 =H, R 2 =R 3 =R 4 =R 8 =OMe, R 9 =Cl wherein (0.95 g, 1.83 mmol) in dry dichloromethane (15 ml) was cooled to 0° C., pyridinium dichromate (1.92 g, 8.17 mmol) was added and the mixture was stirred at room temperature for 3 h. Filtration through celite (3.00 g), washing with dichloromethane (30 ml) and concentration afforded the crude product which was purified by silica gel column chromatography (eluent-3% acetone in pet ether) to yield the title compound of the formula (1B) wherein R=OTBS, R 1 =R 5 =R 6 =R 7 =R 10 =H, R 2 =R 3 =R 4 =R 8 =OMe, R 9 =Cl (0.32 g, 34%), which on deprotection of TBDMS group using the procedure described in example 10 furnished the compound of formula (67).

Spectral data of compound of the formula of structure (67)

1 H NMR (CDCl 3 +CCl 4 ): δ 2.96 (dd, J=18 Hz and 2 Hz, 1H), 3.33 (dd, J=18 Hz and 6 Hz, 1H), 3.75 (s, 6H), 3.86 (s, 3H), 3.91 (s, 3H), 4.45–4.54 (m, 1H), 6.42 (s, 2H), 6.81 (d, J=8 Hz, 1H), 7.21–7.29 (m, 1H), 7.48 (bs, 1H).

13 C-NMR (CDCl 3 +CCl 4 ): δ 37.79, 55.87 (2C), 60.58, 71.57, 106.23 (2c), 111.31, 122.41, 126.82, 127.59, 128.58 (2C), 130.05, 135.90, 138.07, 153.36 (2C), 156.48, 162, 51, 206.95

Preparation of 5-Hydroxy-3-(3-fluoro-4-methoxyphenyl)-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one of formula (64)

4-Bromo-2-fluoroanisole (1.08 g, 5.29 mmol) and magnesium metal (0.13 g, 5.29 mmol) were placed in a 100 ml two-necked round bottom flask under argon atmosphere. Dry tetrahydrofuran (10 ml) was added and the mixture was stirred at room temperature for 2 h. It was then cooled to 0° C., 4-tert-butyldimethysilyloxy-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one (1.00 g, 2.64 mmol) in dry tetrahydrofuran (10 ml) was added dropwise, stirred at 0° C. for 1 h and then at room temperature for 2 h. The reaction was then quenched with saturated ammonium chloride solution (50 ml) and tetrahydrofuran was removed under reduced pressure. The residual reaction mixture was extracted with ethyl acetate (3×50 ml), washed with water (2×20 ml) followed by brine (10 ml), dried (sodium sulfate) and concentrated. Purification by column chromatography over silica gel (eluent-5–8% acetone in pet ether) afforded the compound of formula (4A) wherein R 1 =R 5 =R 6 =R 7 =R 10 =H, R 2 =R 3 =R 4 =R 8 =OMe, R 9 =F (1.20 g, 90%).

The above compound of formula (4A) wherein R 1 =R 5 =R 6 =R 7 =R 10 =H, R 2 =R 3 =R 4 =R 8 =OMe, R 9 =F (0.50 g, 1.00 mmol) in dry dichloromethane (10 ml) was cooled to 0° C., pyridinium dichromate (0.47 g, 2.00 mmol) was added, the mixture was stirred at the same temperature for 1 h and then stirred at room temperature for 8 h. It was then filtered through celite (2.00 g) and washed with dichloromethane (20 ml). The combined dichloromethane layer was washed with water (2×10 ml) followed by brine (5 ml), dried (sodium sulfate), concentrated and purified by column chromatography over silica gel (eluent-2–5% acetone in pet ether) to afford the compound of formula (1B) wherein R=OTBS, R 1 =R 5 =R 6 =R 7 =R 10 =H, R 2 =R 3 =R 4 =R 8 =OMe, R 9 =F (0.24 g, 48%), which on deprotection of TBDMS group using the procedure described in example 10 furnished the compound of formula (64)

Spectral data of compound of the formula of structure (64)

1 H-NMR (CDCl 3 +CCl 4 ): δ 2.93 (dd, J=16 Hz and 4 Hz, 1H), 3.30 (dd, J=16 Hz and 6 Hz, 1H), 3.70 (s, 6H), 3.82 (s, 3H), 3.85 (s, 3H), 4.45–4.60 (m, 1H), 6.40 (s, 2H), 6.78–6.91 (m, 1H), 7.00–7.20 (m, 2H).

13 C-NMR (CDCl 3 ): δ 37.86, 55.84 (2C), 60.58, 71.50, 106.16 (2C), 112.56, 115.72, 116.12, 125.35, 127.00 (2C), 136.01, 137.92, 149.28, 149.50, 153.32 (2C), 162.80, 207.17.

Mass (m/z): 388 (M + ).

Preparation of 5-Hydroxy-2-(4-methoxy-3-nitrophenyl)-3-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one of formula (46)

3,4,5-Trimethoxyiodobenzene (0.20 g, 0.68 mmol) in dry tetrahydrofuran (7 ml) was stirred under nitrogen at −78° C. and n-butyl lithium (0.3 ml of 2.3 M solution, 0.68 mmol) was added dropwise. The reaction mixture was stirred at the same temperature for 1.5 h and then 4-tert-butyldimethysilyloxy-2-(3,4,5-trimethoxyphenyl)-cyclopent-2-en-1-one (0.25 g, 0.68 mmol) in dry tetrahydrofuran (5 ml) was added dropwise. The reaction mixture was stirred at −78° C. for ½ h and at RT for 1 h. It was then quenched with saturated ammonium chloride solution (10 ml), tetrahydrofuran was removed under reduced pressure, product was extracted with ethyl acetate (2×15 ml) washed with water (1×10 ml), dried (sodium sulfate), concentrated and purified by column chromatography over silica gel (eluent-10% acetone in pet ether) to afford the compound of the formula (4A) wherein R 1 =R 4 =R 5 =R 6 =R 10 =H, R 3 =R 7 =R 8 =R 9 =OMe, R 2 =NO 2 (0.14 g, 40%).

The above alcohol of formula (4A) wherein R 1 =R 4 =R 5 =R 6 =R 10 =H, R 3 =R 7 =R 8 =R 9 =OMe, R 2 =NO 2 (0.10 g, 0.19 mmol) in dry dichloromethane (10 ml) was refluxed with pyridinium dichromate (0.14 g, 0.37 mmol) for 18 h under nitrogen atmosphere. It was then filtered through celite (2.00 g) and washed with dichloromethane (30 ml). The combined dichloromethane layer was washed with water (2×10 ml) followed by brine (5 ml), dried (sodium sulfate), concentrated and purified by column chromatography over silica gel (eluent-10% acetone in pet ether) to afford the compound of formula (1B) wherein R=OTBS, R 1 =R 4 =R 5 =R 6 =R 10 =H, R 3 =R 7 =R 8 =R 9 =OMe, R 2 =NO 2 (0.06 g, 52%), which on deprotection of TBDMS group using the procedure described in example 10 furnished the compound of formula (46)

Spectral data of compound of the formula of structure (46)

1 H NMR (CDCl 3 +CCl 4 ): δ 3.02 (bd, J=16 Hz, 1H), 3.27 (dd, J=16 Hz and 6 Hz, 1H) 3.68 (s, 6H), 3.88 (s, 3H), 3.97 (s, 3H), 4.53 (bs, 1H, D 2 O exchangeable), 5.28–5.30 (m, 1H), 6.59 (s, 2H), 7.07 (d, J=8 Hz, 1H), 7.45 (bd, J=8 Hz, 1H), 7.79 (bs, 1H)

Preparation of Compound of the Formula (58) from the Compound of the Formula (51)

A mixture of compound of the formula (51) (0.300 gm, 0.67 mmol), aluminium chloride (0.180 gm, 1.35 mmol) and benzene (10 ml) was stirred at 50° C. under argon atmosphere. It was then cooled and quenched with cold dilute hydrochloric acid (10 ml) and extracted with ethyl acetate (2×2 0 ml). The organic layer was washed with water (2×15 ml) followed by brine (10 ml), dried over sodium sulfate and concentrated under reduced pressure. Purification by column chromatography over silica gel (eluent 8%, 10% acetone in petroleum ether) afforded pure compound of the formula (58) (0.180 gm, 66%).

Spectral data of compound of the formula of structure (58)

1 H NMR (CDCl 3 +CCl 4 ): δ 2.94 (bd, J=18 Hz, 1H), 3.32 (dd, J=18 Hz and 8 Hz, 1H), 3.76 (s, 6H), 3.88 (s, 6H), 5.29–5.40 (m, 1H), 6.44 (s, 2H), 6.65–6.75 (m, 2H), 6.84 (bs, 1H)

Mass (m/z): 401 (M + ).

Preparation of Compound of the Formula (42) from the Compound of the Formula (40)

A mixture of compound of the formula (40) (0.100 gm) and tetrahydrofuran-acetic acid-water (3:1:1, 20 ml) was heated at 50° C. for 20 hr. It was then neutralized by aq. ammonia and extracted with ethyl acetate, dried over sodium sulfate, concentrated and purified by column chromatography to yield pure compound of the formula (42) (0.070 gm, 77%).

Spectral data of compound of the formula of structure (42)

1 H NMR (CDCl 3 +CCl 4 ): δ 2.68 (bd, J=18 Hz, 1H), 3.00 (dd, J=18 Hz and 6 Hz, 1H), 3.70 (s, 6H), 3.84 (s, 6H), 5.18–5.35 (m, 1H), 6.43 (s, 2H), 6.62–6.80 (m, 2H), 6.88 (bs, 1H).

In Vitro Cytotoxicity of the Cyclopentenone Derivatives

A number of the cyclopentenone derivatives were tested for cytotoxicity against 9 human tumor cell lines. Briefly, a three day MTT cytotoxicity assay was performed, which is based on the principle of uptake of MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide), a tetrazolium salt, by the metabolically active cells where it is metabolized by active mitochondria into a blue colored formazan product that is read spectrophotometrically. MTT was dissolved in phosphate buffered saline with a pH of 7.4 to obtain an MTT concentration of 5 mg/ml; the resulting mixture was filtered through a 0.22 micron filter to sterilize and remove a small amount of insoluble residue. For each type of tumor cell, 10000 to 15000 cells were seeded in a 96-well culture plate and incubated with the individual cyclopentenone derivatives in a CO 2 incubator for a total of 72 hours. Control cells not treated with the cyclopentenone derivatives were similarly incubated. The assay was terminated by adding 100 ug (20 ul) of MTT to each well, then incubating for additional one hour, and finally adding 50 ul of 10% SDS-0.01N HCl to each well to lyse the cells and dissolve formazan. After incubating for one hour, the plate was read spectrophotometrically at 540 nm and the percentage of cytotoxicity calculated using the following formula:

Cytotoxicity percentage=100×[1−(X/R 1 )],

where X=(absorbance of treated sample at 540 nm)−(absorbance of blank at 540 nm)

R 1 =absorbance of control sample at 540 nm.

The ED 50 Values of the cytotoxicity defined as the concentration at which 50% of the cells are killed in vitro was calculated for each cell line treated with each of the cyclopentenone derivatives.

The cell lines are PTC (all colon), MOLT-4 (leukemia), SW620 (ovary), DU145 (prostate), KB (oral squamous cell), L132 (lung), MIAPaCa2 (Pancreas), Hep2, (larynx), PA-1 (ovary), HuTu80 (duodenum), ECV 304 (endothelial), and 293 (kidney).

The ED 50 values of in vitro cytotoxicity of the cyclopentenone derivatives of this invention are shown in the Table 3.

The cyclopentenone derivatives were checked for their effects on tubulin polymerization in in vitro. Briefly, the tubulin assembly reaction was performed at 37° C. in buffer containing 80 mM PIPES, 1 mM EGTA, 1.0 mM GTP and 1 mM MgCl 2 (pH 6.9) at a tubulin concentration of 1 mg/ml in the presence or absence of the cyclopentenone derivatives. The final concentration of the cyclopentenone derivatives in the reaction mixture varied from 1–5 uM. The derivatives were dissolved in 0.1% DMSO. The control experiments were carried out with 0.1% DMSO. The tubulin polymerization was followed by measurement of the absorbance of the solution at 340 nm every 30 seconds. The IC50 values for the inhibition of Tubulin Polymerization by the cyclopentenone derivative are shown in Table 4. As shown below the cyclopentenones derivatives inhibited the Tubulin polymerization with IC50 values ranging from 1.4–2.9uM in vitro. Thus the cyclopentenone derivatives mediated their observed anticancer activities by tubulin depolymerization.

Human squamous cell carcinoma (KB) were plated in a 25 cm 2 flask. When cultures achieved confluence, the cyclopentenone derivative of structure 20 was added to cells. The final concentration of derivative of the structure 20 in the flask was 5 ug/ml. The untreated wells served as controls. The cells were incubated with the drug for 2 different time points of 6 and 16 hours at 37° C. The cells were collected by centrifugation at 2000 r.p.m. for 10 minutes. The supernatant was gently removed and discarded while Lysis Buffer was added to the cell pellet (25 ul of lysis buffer per 1×10 4 cell). The cell lysate was incubated on ice for 10 minutes and centrifuged at 10,000-×g for 1 minute. The supernatant was transferred to a new tube and kept on ice. 50 ul of the cell lysate was added in a 96 well plate. To this was added 2× Reaction Buffer. Prior to using reaction buffer 10 ul of fresh DTT stock per 1 ml of 2× Reaction Buffer was added. To each well 5 ul of Caspase-3 colorimetric substrate (DEVD-pNA) was added. The plate was incubated for 1–2 hours at 37° C. and read at 405 nm.

The level of caspase enzymatic activity in the cell lysate is directly proportional to the absorbance at 405 nm. Table 5 shows the level of induction of Caspase 3 in KB cells treated with one of the cyclopentenone derivatives.

Human endothelial cells (ECV304) were plated at the density of 8–10×10 5 cells per 2 ml in a six well plate. After an overnight incubation of cells at 37° C., cyclopentenone derivatives at a concentration of 5 ug/ml was added to the wells. The untreated wells served as controls. The plates were incubated for 4 hours at 37° C. The medium was collected from all the wells (control and treated) and spun down at 2000 r.p.m to remove the cellular material. The supernatant was collected and used for ELISA (quantikine human VEGF, R&D Systems). The assay employs the quantitative sandwich enzyme immuonoassay technique. A monoclonal antibody specific for VEGF has been pre-coated onto a microplate. Standards and samples were pipetted into the wells and VEGF present was bound by the immobilized antibody. After washing away the unbound substances, an enzyme-linked polyclonal antibody specific for VEGF was added to the wells. Following a wash to remove any unbound antibody-enzyme reagent, a substrate solution was added to the wells and color developed in proportion to the amount of VEGF bound in the initial step. The optical density of each well was determined within 30 minutes using a microplate reader set to 450 nm and reference wavelength at 540 nm. The VEGF levels were inhibited by the addition of cyclopentenone derivatives in vitro. The present reduction in the inhibition of VEGF by the cyclopentenone derivatives is shown in Table 6.

A PubMed search of the National Library of Medicine was carried out to determine the relevance of the cell lines used by us for determining the anticancer activity of the peptides. While HT29 (human colon) showed 2021 “hits” when searched with reference to cancer, other human cancer cell lines used by us also showed large number of hits (6848 for K562, 2532 for MOLT-4, 542 for DU145, 1063 for MCF-7, 542 for DU145 and 182 for PA-1). This clearly shows the extensive use of these cell lines in cancer research. Further, it is a common and standard practice and norm for testing molecules for anticancer activity in vitro on human tumor cell lines. (Br J Cancer. 2001 May 18; 84(10):1289–90 Flasks, Fibers and Flanks—Preclinical tumor models for predicting clinical antitumor activity). The authors report that in vitro activity against 6 or more lung or breast cancer cell lines does predict xenograft activity against these tumor types. In articles “Semin Oncol 1992 December; 19;(6):622–38 (The National Cancer Institute: cancer drug discovery and development program) and “Jpn J Antibiot 1977 Dec. 30; Suppl:35–40 (Antitumor screening procedures of the National Cancer Institute)” extensive use of human tumor cell lines for identification of potential cytotoxic drugs is described.”

In Vivo Anti-tumor Activity of Compound of Formula No. 49 on Primary Tumor (Colon) Xenografted Mice

PTC tumor xenografts were grown in Balb/c athymic mice by subcutaneous inoculation of a single cell suspension of PTC cells (15×10 6 cells/100 μL). The tumor bearing animals were divided into 2 groups of three animals each including one group comprising untreated control animals. Treatment with compound of formula no. 49 was initiated when the average tumor volumes, as measured using a vernier caliper, were between 500 mm 3 . Compound of formula no. 49 was administered intravenously to the assigned group of tumor bearing animals at a dose of 0.5 mg/100 μL once a day and the treatment was continued for a period of 14 days.

The antitumor activity of the compound was monitored by measuring tumor volumes every fourth day using the formula W*W*L*0.4 (W=smaller diameter, L=larger diameter). The percentage inhibition of tumor growth was calculated using the formula (1-tumor volume-treated/tumor volume-control)*100. FIG. 1 shows the tumor kinetics till day 23 in the treated and untreated animals. Compound of formula no. 49 showed significant antitumor activity on PTC xenografts. The percentage inhibition of tumor growth caused compound of formula no. 49 as compared to controls on day 23 was 45.8%.