Cyclization of (+)- and (–)-S-(2-methylprop-1-enyl)-L-cysteine S-oxides

Autor:	John F. Carson, Robert E. Lundin
Rok vydání:	1976
Předmět:	Steric effects chemistry.chemical_classification chemistry.chemical_compound Stereospecificity Base (chemistry) Stereochemistry Chemistry chemistry.chemical_element Ring (chemistry) Sulfur Cysteine Methyl group
Zdroj:	J. Chem. Soc., Perkin Trans. 1. :1195-1199
ISSN:	1364-5463 0300-922X
DOI:	10.1039/p19760001195
Popis:	S-(2-Methylprop-1-enyl)-L-cysteine (5) has been oxidized to two sulphoxides (7a), [α]D25+128°, and (7b), [α]D25–84.3°(in H2O). Cyclization in base was stereospecific. The (+)-sulphoxide (7a) yielded the axial sulphoxide, (1S,3R)-5,5-dimethyltetrahydro-1,4-thiazine-3-carboxylic acid S-oxide (9), and the (–)-sulphoxide (7b) yielded the corresponding equatorial (1R) sulphoxide (10). This establishes the absolute configurations of the acyclic sulphoxides (7a and b) as R and S, respectively, at sulphur. Reduction of the cyclic sulphoxides to the corresponding cyclic sulphide, and reoxidation of this compound gave exclusively the equatorial sulphoxide (10), suggesting a large steric effect of the axial methyl group. Assignments of ring conformations and sulphoxide configurations are based on spectroscopic evidence.
Databáze:	OpenAIRE
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