methyl 3-hydroxy-5-phenylpentanoate

Conditions: temp:-78.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: A solution of 2.0 M LDA in heptane/THF/ethylbezene (9.4 mL, 18.8 mmol) was added slowly to a stirred solution of tert-butylacetate (2.18 g, 18.8 mmol) in dry THF (20 mL) under N2 at −78° C. After being stirred at −78° C. for 25 min., a solution of the above made 3-hydroxy-5-phenyl-pentanoic acid methyl ester (1.3 g, 6.25 mmol) in dry THF (10 mL) was then added through a cannula. The resultant clear solution was stirred at −78° C. for 1 h and then at −55° C. for another 1 h. The reaction was quenched by the addition of 20% aqueous acetic acid (20 mL). Two layers were separated and the aqueous layer was extracted with EtOAc (3×30 mL). Combined organic layer was washed with H2O (50 mL, brine (50 mL, dried with sodium sulfate, and then concentrated to leave an oil. Flush column chromatography purification on silica gel (4:1 Hexane/EtOAc to 2:1 Hexane/EtOAc) afforded the intermediate 5-Hydroxy-3-oxo-7-phenyl-heptanoic acid tert-butyl ester as a colorless oil (1.74 g, 95%). 1H NMR (300 MHz, CDCl3) δ1.45 (s, 9H), 1.6-1.9 (m, 2H), 2.50-2.85 (m, 4H), 3.35 (s, 3 H), 3.95-4.10 (m, 1H), 7.10-7.30 (m, 5H). ESMS calcd (C17H24O4): 292.2; found: 291.2 (M−H)+. was then added through a cannula The resultant clear solution was stirred at −78° C. for 1 h at −55° C. for another 1 h The reaction was quenched by the addition of 20% aqueous acetic acid (20 mL) Two layers were separated the aqueous layer was extracted with EtOAc (3×30 mL) Combined organic layer was washed with H2O (50 mL, brine (50 mL dried with sodium sulfate concentrated to leave an oil Flush column chromatography purification on silica gel (4:1 Hexane/EtOAc to 2:1 Hexane/EtOAc)

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

Procedure: To a stirred solution of (S)-(−)-α,α-diphenyl-2-pyrrolidinemethanol (770 mg, 3 mmol) in dry THF (100 mL) was added 2 M THF solution of borane-dimethylsulfide complex (11 mL, 22 mmol) at rt under N2. After being stirred at rt for 16 h, a solution of 3-Oxo-5-phenyl-pentanoic acid methyl ester (JACS, 1974, 1082-1087) (6.5 g, 31.5 mmol) in dry THF (20 mL) was added dropwise at rt over a period of 1 h. The resultant clear solution was stirred at rt for another 30 min and was then cooled to 0° C. in an ice bath. The reaction was quenched by the addition of MeOH (90 mL) and the reaction pot was concentrated under reduced pressure. The residue was taken up with EtOAc (200 mL) and washed successively with H2O (100 mL), citric acid (100 mL), 5% NaHCO3 (100 mL) and brine (100 mL). After being dried over Na2SO4, the solvent was removed to afford an oil. Flush column chromatography purification on silica gel gave 3-Hydroxy-5-phenyl-pentanoic acid methyl ester as an oil (3.3 g, 51%) with 92% e.e. (judged from the corresponding Mosher's ester). 1H NMR (300 MHz, CDCl3) δ1.6-1.9 (m, 2H), 2.4-2.6 (m, 2H), 2.65-2.9 (m, 2H), 3.05 (d, 1H, J=6), 3.7 (s, 3H), 3.95-4.10 (m, 1H), 7.10-7.35 (m, 5H). ESMS calcd (C12H16O3): 208.1; found: 209.1 (M+H)+. The resultant clear solution was stirred at rt for another 30 min was then cooled to 0° C. in an ice bath The reaction was quenched by the addition of MeOH (90 mL) the reaction pot was concentrated under reduced pressure washed successively with H2O (100 mL), citric acid (100 mL), 5% NaHCO3 (100 mL) and brine (100 mL) After being dried over Na2SO4 the solvent was removed to afford an oil Flush column chromatography purification on silica gel