A simple and general chiral silicon Lewis acid for asymmetric synthesis: highly enantioselective [3+2] acylhydrazone-enol ether cycloadditions

Seiji Shirakawa; Pamela J Lombardi; James L Leighton

doi:10.1021/ja052307+

A simple and general chiral silicon Lewis acid for asymmetric synthesis: highly enantioselective [3+2] acylhydrazone-enol ether cycloadditions

J Am Chem Soc. 2005 Jul 20;127(28):9974-5. doi: 10.1021/ja052307+.

Authors

Seiji Shirakawa¹, Pamela J Lombardi, James L Leighton

Affiliation

¹ Department of Chemistry, Columbia University, New York, New York 10027, USA.

PMID: 16011341
DOI: 10.1021/ja052307+

Abstract

A highly diastereo- and enantioselective [3 + 2] acylhydrazone-enol ether cycloaddition mediated by a simple chiral silane Lewis acid is described. The reactions are highly practical, as demonstrated by a larger scale (5 g of the hydrazone) reaction in which the product was obtained after recrystallization in 93% yield and 99% ee. Evidence for a stepwise mechanism and a model for the asymmetric induction are presented, as well.