Benzenemethanethiol, alpha,alpha-diphenyl- → (2S,4R)-1-(naphthalene-2-sulfonyl)-4-tritylsulfanyl-pyrrolidine-2-carboxylic acid methyl ester

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Reaction Conditions

Reaction Steps

64.2 g (167 mmol) of triphenylmethanthiol was slowly added at room temperature to a solution of 17.9 g (160 mmol) of potassium tert-butylate in 300 ml DMF and stirred mechanically for 30 min. Then 63 g (152 mmol) of (4S, 2S)-4-methanesulfonyloxy-1-(naphthalene-2-sulfonyl)-pyrrolidine-2-carboxylic acid methylester in 300 ml DMF were added at 20° C. by cooling at the end with an ice bath. The reaction was heated for 1.3 h at 100° C., cooled, evaporated to 400 ml and extracted with 250 ml aqueous saturated NH4Cl/EtOAc (3×300). The organic phases were washed with aq. 10% NaCl, dried (Na2SO4) and evaporated. Flash chromatography (CH2Cl2/MeOH 99:1) gave 58.6 g (65%, (2S,4R)/(2R,4R)-isomer ca 4:1, 1H-NMR) and 9.2 g (10%, (2S,4R)/(2R,4R)-isomer ca 1:1, 1H-NMR) of (2S,4R)-1-(naphthalene-2-sulfonyl)-4-tritylsulfanyl-pyrrolidine-2-carboxylic acid methyl ester, MS: 594 (MH+).

Provenance & Evidence