STUDIES ON AMINO ACIDS AND PEPTIDES - VII SYNTHESES OF ASPARTAME AND THIOASPARTAME

Article abstract of DOI:10.1016/S0040-4020(01)88631-2

The protected aspartame, 4, has been prepared from the benzyl ester of N-benzyloxycarbonyl-S-aspartic acid, 1, and the methyl S-phenylalanate, 3, using 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide, LR, as a coupling reagent.Another protected aspartame, 7, has been prepared from the tert-butyl ester of 1--succinimide, 6, and methyl S-phenylalanate, 3.Thiations of 4/7 by LR produces a protected thioaspartame, 5/9.Deprotection of 7 and 9 gives aspartame, 8, and the slightly sweet thioaspartame, 10, in high yields.