Methanesulfonic Acid → HCID 86585072, compound

Participants

Reaction Conditions

Reaction Steps

To a suspension of 6.7 ml (103.3 mmol) methanesulfonic acid, 14.4 ml (103.3 mmol) triethylamine and 28.8 g (107.6 mmol) triphenylphosphine in 280 ml toluene was added a suspension of 21.12 g (86.12 mmol) (2R,4R)-4-Hydroxy-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester 2-methyl ester [prepared according to “Synthesis of macrocyclic dilactones by cyclization of sulfonium salts”. T. Nakamura, H. Matsuyama, N. Kamigata, M. Iyoda, J. Org. Chem. (1992), 57(14), 3783-9] in 180 ml toluene. After adding 21.6 ml (112 mmol) of diisopropyl azodicaboxylate (exothermic!) the solution was heated for 2.5 h at 80° C. and was stirred at RT for 1 day. 300 ml water was added at RT and extracted with ethylacetate (3×300 ml). The organic phase was washed with aqueous 1M KHSO4 (2×100 ml), brine (2×150 ml), dried over Na2SO4 and evaporated to give 27.85 g (2R,4S)-4-Methanesulfonyloxy-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester as crude product which was dissolved in THF and treated with LiOH according to 5.2.to give (2R,4S)-4-Methanesulfonyloxy-pyrrolidine-1,2-dicarboxylic acid 1-tert-butyl ester.

Provenance & Evidence