benzyl 4-methyl-2-oxopentanoate

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 2-Oxo-4-methyl pentanoic acid sodium salt (10 g, 65.7 mmol) and benzyl chloride (8 g, 63 mmol) in 300 ml DMF was stirred at 40°-50° C. for 5 h. It was filtered, and the filtrate was evaporated under reduced pressure to provide an oil. The oil was dissolved in chloroform, washed with water, dried, filtered, and evaporated to provide the desired product (13 g, 94%). 1H NMR (CDCl3, TMS) δ0.95 (d,6H), 2.15 (m,1H), 2.7 (d,2H), 5.28 (s,2H), 7.4 (m,5H). Mass spectrum: (M+H)+ =221. It was filtered the filtrate was evaporated under reduced pressure to provide an oil washed with water dried filtered evaporated

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: With reference to reaction Scheme 2, a slurry of 25 g (0.164 mol) of the sodium salt of 4-methyl-2-oxopentanoic acid, sodium salt in anhydrous N,N-dimethylformamide (50 ml) containing 19.6 ml (0.164 mol) of benzyl bromide was agitated at room temperature for 4 days. The solvent was removed in vacuo. The residue was dissolved in 250 ml of hexane and washed with water (3×50 ml) and brine (50 ml). After drying over anhydrous magnesium sulfate, the solution was filtered and concentrated in vacuo to give 33.2 g (92% yield) of benzyl 4-methyl-2-oxopentanoate (1a) as a viscous, colorless oil. TLC: Rf 0.70 (ethyl acetate-hexane 1:4); 1H NMR(CDCl3) δ 0.94(d, 6H), 2.18(m, 1H), 2.71(d, 2H), 5.26(s, 2H), 7.37(m, 5H); 13C NMR (CDCl3) δ 22.5, 24.2, 48.1, 67.9, 128.7, 128.8, 128.9, 134.7, 161.3, 194.0. With reference to reaction Scheme 2 The solvent was removed in vacuo The residue was dissolved in 250 ml of hexane washed with water (3×50 ml) and brine (50 ml) After drying over anhydrous magnesium sulfate the solution was filtered concentrated in vacuo

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Ethyl 2-(diethylphosphono)propanoate (23.9 g.) was added to dry toluene (250 mls.) containing 80% sodium hydride in mineral oil (3.0 g.) at room temperature. The resultant mixture was heated to 50°-60° C. for 5 minutes and then cooled to -30° to -40° C. To the cooled mixture was added benzyl 4-methyl-2-oxopentanoate (20 g.) and the resulting mixture was allowed to warm to room temperature over a period of 1 hour. The toluene solution was washed with dilute citric acid (50 mls.), water (2×50 mls.) and then dried over anhydrous sodium sulfate. The toluene was removed by evaporation in vacuo to yield E and Z benzyl 3-(ethoxycarbonyl)-2-(2-methylpropyl)butenoate as a mixture of isomers in the form of an oil. cooled to -30° to -40° C The toluene solution was washed with dilute citric acid (50 mls.), water (2×50 mls.) dried over anhydrous sodium sulfate The toluene was removed by evaporation in vacuo

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Ethoxycarbonylmethylenetriphenylphosphorane (53.8 g., 0.155 mol.) was dissolved in dry dichloromethane (400 mls.) and the resulting solution was cooled to 0° C. To the cooled solution was added a solution of benzyl 4-methyl-2-oxopentanoate (34.0 g., 0.155 mol.) in dry dichloromethane (100 mls.) over a period of 25 minutes and the reaction mixture was then heated under reflux for 1 hour. The solvent was removed from the reaction mixture by evaporation in vacuo to yield an off-white solid. The solid was extracted with hexane (3×200 mls.) and the solvent was removed from the combined hexane extracts to yield a crude product as a yellow oil. The crude product was purified by distillation (0.6 mm Hg), to yield E and Z benzyl 3-(ethoxycarbonyl)-2-(2-methylpropyl)propenoate (41.0 g.) being collected at 137°-142° C. the reaction mixture was then heated under reflux for 1 hour The solvent was removed from the reaction mixture by evaporation in vacuo to yield an off-white solid The solid was extracted with hexane (3×200 mls.) the solvent was removed from the combined hexane to yield a crude product as a yellow oil The crude product was purified by distillation (0.6 mm Hg)

Conditions: temp:0.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Ethoxycarbonylmethylenetriphenylphosphorane (53.8 g., 0.155 mol.) was dissolved in dry dichloromethane (400 mls.) and the resulting solution was cooled to 0° C. To the cooled solution was added a solution of benzyl 4-methyl-2-oxopentanoate (34.0 g., 0.155 mol.) in dry dichloromethane (100 mls.) over a period of 25 minutes and the reaction mixture was then heated under reflux for 1 hour. The solvent was removed from the reaction mixture by evaporation in vacuo to yield an off-white solid. The solid was extracted with hexane (3×200 mls.) and the solvent was removed from the combined hexane extracts to yield a crude product as a yellow oil. The crude product was purified by distillation (0.6 mm Hg), to yield E and Z benzyl 3-(ethoxycarbonyl)-2-(2-methylpropyl)propenoate (41.0 g.) being collected at 137°-142° C. the reaction mixture was then heated under reflux for 1 hour The solvent was removed from the reaction mixture by evaporation in vacuo to yield an off-white solid The solid was extracted with hexane (3×200 mls.) the solvent was removed from the combined hexane to yield a crude product as a yellow oil The crude product was purified by distillation (0.6 mm Hg)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 2-Oxo-4-methyl pentanoic acid sodium salt (10 g, 65.7 mmol) and benzyl chloride (8 g, 63 mmol) in 300 ml DMF was stirred at 40°-50° C. for 5 h. It was filtered, and the filtrate was evaporated under reduced pressure to provide an oil. The oil was dissolved in chloroform, washed with water, dried, filtered, and evaporated to provide the desired product (13 g, 94%). 1H NMR (CDCl3, TMS) δ0.95 (d,6H), 2.15 (m,1H), 2.7 (d,2H), 5.28 (s,2H), 7.4 (m,5H). Mass spectrum: (M+H)+ =221. It was filtered the filtrate was evaporated under reduced pressure to provide an oil washed with water dried filtered evaporated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A mixture of 2-Oxo-4-methyl pentanoic acid sodium salt (10 g, 65.7 mmol) and benzyl chloride (8 g, 63 mmol) in 300 ml DMF was stirred at 40°-50° C. for 5 h. It was filtered, and the filtrate was evaporated under reduced pressure to provide an oil. The oil was dissolved in chloroform, washed with water, dried, filtered, and evaporated to provide the desired product (13 g, 94%). 1H NMR (CDCl3, TMS) δ0.95 (d,6H), 2.15 (m,1H), 2.7 (d,2H), 5.28 (s,2H), 7.4 (m,5H). Mass spectrum: (M+H)+ =221. It was filtered the filtrate was evaporated under reduced pressure to provide an oil washed with water dried filtered evaporated

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: With reference to reaction Scheme 2, a slurry of 25 g (0.164 mol) of the sodium salt of 4-methyl-2-oxopentanoic acid, sodium salt in anhydrous N,N-dimethylformamide (50 ml) containing 19.6 ml (0.164 mol) of benzyl bromide was agitated at room temperature for 4 days. The solvent was removed in vacuo. The residue was dissolved in 250 ml of hexane and washed with water (3×50 ml) and brine (50 ml). After drying over anhydrous magnesium sulfate, the solution was filtered and concentrated in vacuo to give 33.2 g (92% yield) of benzyl 4-methyl-2-oxopentanoate (1a) as a viscous, colorless oil. TLC: Rf 0.70 (ethyl acetate-hexane 1:4); 1H NMR(CDCl3) δ 0.94(d, 6H), 2.18(m, 1H), 2.71(d, 2H), 5.26(s, 2H), 7.37(m, 5H); 13C NMR (CDCl3) δ 22.5, 24.2, 48.1, 67.9, 128.7, 128.8, 128.9, 134.7, 161.3, 194.0. With reference to reaction Scheme 2 The solvent was removed in vacuo The residue was dissolved in 250 ml of hexane washed with water (3×50 ml) and brine (50 ml) After drying over anhydrous magnesium sulfate the solution was filtered concentrated in vacuo