He X, Buchotte M, Guillot R, Deloisy S, Aitken DJ. A case study of the MAC (masked acyl cyanide) oxyhomologation of
N,
N-dibenzyl-L-phenylalaninal with
anti diastereoselectivity: preparation of (2
S,3
S)-allophenylnorstatin esters.
Org Biomol Chem 2022;
20:1769-1781. [PMID:
35166749 DOI:
10.1039/d1ob02411f]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The three-component reaction between a protected α-amino aldehyde, an alcohol and an α-silyloxymalononitrile provides an expedient access to protected α-hydroxy-β-amino acid derivatives. The prototypical process, performed on N-Cbz-phenylalaninal, is known to proceed with syn diastereoselectivity. The present study demonstrates that the diastereoselectivity of the reaction can be inverted, using the rationale of a Felkin-Anh interaction model. Reactions performed on N,N-dibenzyl-L-phenylalaninal proceed with a high anti diastereoselectivity, providing a panel of synthetically useful ester derivatives of (2S,3S)-allophenylnorstatin. The procedure is exploited to accomplish one of the most efficient syntheses of the title compound to date, in 3 steps (66% yield) from N,N-dibenzyl-L-phenylalaninal.
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