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anti-Selective Aldol Reactions of Amino Acid Ester Enolates. Application to the Synthesis of α-Alkylated β-Hydroxy Amino Acids

✍ Scribed by Grandel, Roland ;Kazmaier, Uli ;Nuber, Bernhard

Publisher
John Wiley and Sons
Year
2006
Tongue
English
Weight
842 KB
Volume
1996
Category
Article
ISSN
0947-3440

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✦ Synopsis

Abstract

Deprotonation of N‐protected esters of the amino acids alanine 1, ethylglycin 6, valine 7, and phenylalanine 8 with LDA and subsequent addition of various metal salts result in the formation of a probably chelated metal enolate. Aldol reactions of these enolates with aldehydes afford the anti isomers of α‐alkylated α‐amino‐β‐hydroxy acids in a highly diastereoselective fashion. Best results are obtained with titanium enolates, bulky aliphatic aldehydes, and sterically demanding amino acids.

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