82835-13-0

(Chemical Equation Presented) L-Cysteine is a stimulating starting product for the generation of transient sulfenic acids, such as 4, 6, 9, and 15, which add to suitable acceptors, allowing formation of sulfoxides showing a biologically active residue. These sulfoxides are easily isolated in enantiomerically pure form. For instance, N-(tert-butoxycarbonyl)-L-cysteine methyl ester (1a) furnished in few steps sulfenic acid 9a, which was readily converted into (R,SS)-(2-tert-butoxycarbonylamino-2-methoxycarbonyl- ethylsulfinyl)ethene (22), the methyl ester of Boc-protected nor-alliin. Moreover, the addition of 9a to 2-methyl-1-buten-3-yne has led to a sulfur epimeric and separable mixture of (CR)-2-(2-tert-butoxycarbonylamino-2- methoxycarbonyl-ethylsulfinyl)-3-methyl-buta-1,3-dienes 10a and 11a, still possessing a "masked" sulfenic acid function, producible from their cysteine moieties once the dienes have been converted into the desired derivatives.

L-cysteine is a stimulating starting product for the generation of transient sulfenic acids that add to suitable acceptors, allowing formation of sulfoxides showing a biologically active residue. For instance, N-(tert-butoxycarbonyl)-L-cysteine methyl ester furnished in few steps (R)-2-tert-butoxycarbonylamino-2-methoxycarbonyl-ethanesulfenic acid, which was readily converted into (R,SS)-(2-tert-butoxycarbonylamino-2- methoxycarbonyl-ethylsulfinyl)ethene, the methyl ester of Boc-protected nor-alliin. Copyright Taylor & Francis Inc.