Trifluoroacetic acid → Benzyl 1,6-diazaspiro[3.5]nonane-1-carboxylate

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Reaction Steps

To a solution of an optically-active compound of 1,6-diazaspiro[3,5]-nonane-1,6-dicarboxylic acid 1-benzyl ester 6-tert-butyl ester (5.35 g) in chloroform (134 ml) cooled to 0° C. was added trifluoroacetic acid (27 ml), and the mixture was stirred for 30 minutes, warmed to room temperature and stirred for additional 30 minutes. The reaction mixture was cooled to 0° C., and thereto was added 4M aqueous sodium hydroxide solution (91 ml). The aqueous layer was extracted with chloroform (100 ml, 50 ml) twice, and the combined organic layer was washed with saturated aqueous sodium chloride solution and concentrated under reduced pressure. The resulting residue was purified by silica gel column chromatography (eluent: chloroform/methanol=20/1 to 4/1) to give the titled compound (2.37 g).

Provenance & Evidence