Chloride → (2S,4S)-1-tert-butyl 2-methyl 4-chloropyrrolidine-1,2-dicarboxylate

Participants

Reaction Conditions

Reaction Steps

Via chloride: A solution of 374 g (1.48 mol) (2S,4R)-4-hydroxy-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-methyl ester in 1.61 CH2Cl2 was treated with 680 g (2.6 mol) triphenylphosphine, cooled to 3-5° C. and treated in 10 min with 1.241 (12.8 mol) CCl4, after 2 h at this temperature cooling was stopped, the reaction temperature was raised during 2 h to 35° C. It was cooled down to 20° C. and stirred for further 45 min. After addition of 4 l of n-heptane, the reaction was evaporated to 2.9 l, cooled to 0° C., filtered, the residue was treated twice the same way, the third time by dissolving the residue again in 2 l of CH2Cl2. The solvents were evaporated and filtered through silica gel with hexane/tert.-butyl-methylether 9:1 as eluent. Evaporation of the solvents gave 347 g (89%) of (2S,4S)-4-chloro-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-methyl ester, MS: 246 (MH+).

Provenance & Evidence