α′-Benzoyloxy and α′-methoxymethoxy lithium enolates giving opposite diastereofacial selectivities in aldol reactions. Use of (probable) extended chelation for reversal of stereoselectivities
作者:Anusuya Choudhury、Edward R. Thornton
DOI:10.1016/s0040-4039(00)77578-2
日期:1993.4
The Li enolates of α-benzoyloxy and α-methoxymethoxy ketones 1a and 1c afford nonchelation and chelation aldol products, respectively, both with usefully high diastereofacialselectivities. Evidence suggests that transition state chelation of the benzoyl C=O is responsible for the observed “nonchelation” stereoselectivity of 1a.