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Asymmetric alkylations of a sultam-derived glycinate equivalent: practical preparation of enantiomerically pure α-amino acids

✍ Scribed by Wolfgang Oppolzer; Robert Moretti; Silvia Thomi

Publisher
Elsevier Science
Year
1989
Tongue
French
Weight
155 KB
Volume
30
Category
Article
ISSN
0040-4039

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✦ Synopsis

Deprotonation/alkylation of sultam-derived N-[bis(methyl)thiomethylene]glycinate equivalent 2 gave crystalline products 5 which on mild hydrolysis furnished a-amino acids 2 (-100% e.e.) in high overall yield. Chiral glycine equivalents represent an attractive pivotal source for asymmetric syntheses of enantiomerically pure o-amino acids '. Straightforward alkylations of glycine enolate derivatives are, however, relatively scarce 2 and, despite their elegance, leave plenty of room for more practical and general alternatives.

We report here the advantageous use of the readily available and widely applicable sultam auxiliary 1 3. Me3Almediated acylation of 1 with methyl N-[bis(methylthio)methylene]glycinate (a 4 furnished, after crystallization, "glycinate" 2 (89%) 4*5 which served as a common precursor for various a-amino acids z (Scheme, Table ).

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