Dichloromethane ethylacetate → (2S,4R)-[1-(naphthalene-2-sulfonyl)-4-tritylsulfanyl-pyrrolidin-2-yl]-methanol

Participants

Reaction Conditions

Reaction Steps

Ester reduction, Method A: 57 ml (57 mmol, 1M THF solution) of LAH was added during 15 min to a cold solution (−20° C.) of 28.2 g (47.5 mmol, ca. (2S,4R)/(2R,4R)-isomer ca 4:1) (2S,4R)-1-(naphthalene-2-sulfonyl)-4-tritylsulfanyl-pyrrolidine-2-carboxylic acid methyl ester in 460 ml THF. The reaction was stirred for 20 min, cooled to −78° C. and quenched with a suspension of 15 g silica gel/15 g MgSO4 7H2O in 60 ml aqueous 10% KHSO4. The suspension was stirred for 15 min at room temperature, filtered and washed with THF. After evaporation of the THF, the residue was taken up in CH2Cl2, dried over Na2SO4 and evaporated to give 29.2 g crude product. Flash column chromatography on silica gel with CH2Cl2/EtOAc(2.5%) to CH2Cl2/EtOAc(10%) gave 21.7 g (81%) of (2S,4R)-[1-(naphthalene-2-sulfonyl)-4-tritylsulfanyl-pyrrolidin-2-yl]-methanol and 1.0 g (4%) of [(2R,4R)-4-mercapto-1-(naphthalene-2-sulfonyl)-pyrrolidin-2-yl]MS: 566 (MH+).

Provenance & Evidence