L-cysteine, a versatile source of sulfenic acids. Synthesis of enantiopure alliin analogues.
[reaction: see text] 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,S(S))-(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 (R)-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.
Aversa
Maria C
MC
Dipartimento di Chimica Organica e Biologica, Università degli Studi di Messina, Salita Sperone 31 (vill. S. Agata), 98166 Messina, Italy.
Barattucci
Anna
A
Bonaccorsi
Paola
P
Giannetto
Placido
P
D003545:Cysteine / Q000031:analogs & derivatives* / Q000138:chemical synthesis* / Q000737:chemistry*; D008968:Molecular Conformation; D013237:Stereoisomerism; D013434:Sulfenic Acids / Q000138:chemical synthesis*
D013434:Sulfenic Acids; C006453:alliin; D003545:Cysteine