Diastereoselective side-chain alkylation of (prolinolylmethyl)oxazoles and -oxadiazoles

✍ Scribed by Pohl, Martin ;Thieme, Marion ;Jones, Peter G. ;Liebscher, Jürgen

• Publisher: John Wiley and Sons
• Year: 1995
• Tongue: English
• Weight: 812 KB
• Volume: 1995
• Category: Article
• ISSN: 0947-3440
• DOI: 10.1002/jlac.1995199508210

✦ Synopsis

Abstract

Diastereoselective alkylation of the α‐position of (S)‐(prolinolylmethyl)oxazoles and ‐oxadiazoles 1 leading to side‐chain modified products 2 and 3 was achieved by reaction with LDA and alkylating agents or aldehydes. The products 2 and 3 are precursors of non‐natural chiral α‐amino acids. The influence of substituents, reagents, and reaction conditions on the diastereoselectivity of the alkylation was investigated. A model was proposed explaining the stereochemical outcome of the reaction. Corresponding α‐acylation of prolinolylmethyl heterocycles 1 with chloroformates affording chiral α‐amino esters 4 were not stereoselective.