Water → HCID 20067138, Verbindung

11.5 g (0.1 mole) of methanesulfonyl chloride were added dropwise, whilst ice-cooling to a solution of 13.0 g (0.06 mole) of 1-t-butoxycarbonyl-3-hydroxy-4-methoxypyrrolidine [prepared as described in Step (c) above] in 100 ml of pyridine, and the mixture was stirred overnight whilst ice-cooling. The reaction mixture was then poured into 800 ml of water and extracted with diethyl ether. The extract was washed with water and dried, and the solvent was removed by evaporation under reduced pressure to afford 12.9 g of 1-t-butoxycarbonyl-3-hydroxy-4-methanesulfonyloxypyrrolidine as a brown oily substance. The whole of this oily substance was placed in a 100 ml stainless steel autoclave, and 50 ml of liquid ammonia was added thereto. The mixture was then heated with stirring at 140° C. under pressure for 8 hours. At the end of this time, the excess ammonia was removed by evaporation, and the residue was subjected to silica gel column chromatography eluted with ethanol, to afford 8.0 of cis-3-amino-1-t-butoxycarbonyl-4-methoxypyrrolidine as a brown oily substance.