p-Toluenesulfonic acid → Methyl 7-[2-(2-hydroxy-2-methylheptylthio)-5-oxopyrrolidin-1-yl]-6-oxoheptanoate

Participants

Reaction Steps

To a solution of 15 (50 mg, 0.16 mmol) in ethanol (2 mL) at 0° was added sodium borohydride (10 mg, 0.25 mmol). Two drops of 2N hydrochloric acid (in ethanol) were added at fifteen minute intervals for 1.5 hours. After continued stirring at 0° for one hour, the reaction was diluted with saturated aqueous sodium chloride and extracted three times with chloroform. The combined chloroform layer was dried over sodium sulfate. Removal of the solvent afforded 57 mg of the crude product which was dissolved in 2 mL of methylene chloride and treated with 20 mg of 1-mercapto-2-hydroxy-2-methylheptane in the presence of 15 mg of PTSA at room temperature overnight. It was then diluted with methylene chloride and washed with saturated sodium chloride solution. The separated aqueous layer was extracted twice with methylene chloride and the combined organic layer was dried over magnesium sulfate. The crude product was purified by preparative TLC to give 5.7 mg of methyl 7-[2-(2-hydroxy-2-methylheptylthio)-5-oxopyrrolidin-1-yl]-6-oxoheptanoate (16). IR (CH2Cl2): 1740, 1705 cm-1 ; PMR (CDCl3): δ 4.87 (t, 1H), 4.23 (AB, q, 2H), 3.67 (s, 3H), 2.70-1.20 (m, 22H), 1.20 (s, 3H), and 0.90 (t, 3H); MS: m/z 240.1227 (M+ -lower side chain), calcd. for C12H18NO4, 240.1236.

Provenance & Evidence