Avenoza A, Busto JH, Jiménez-Osés G, Peregrina JM. S(N)2 reaction of sulfur nucleophiles with hindered sulfamidates: enantioselective synthesis of alpha-methylisocysteine.
J Org Chem 2006;
71:1692-5. [PMID:
16468825 DOI:
10.1021/jo051632c]
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Abstract
The work described here demonstrates that the five-membered cyclic alpha-methylisoserine-derived sulfamidate, (R)-1, behaves as an excellent chiral building block for the ring-opening reaction by S(N)2 attack with sulfur nucleophiles at the quaternary carbon. As a synthetic application of this methodology, and to show that this sulfamidate is a valuable starting material, the synthesis of two new alpha-methylisocysteine derivatives has been carried out to cover the lack of alpha- and beta-methylated amino acids that incorporate the cysteine or isocysteine skeleton. These compounds are two new alpha,alpha-disubstituted beta-amino acids (beta(2,2)-amino acids), and the synthetic routes involve nucleophilic ring opening followed by acid hydrolysis.
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