Exclusive <i>α</i>-Coupling in the Aldol Reaction of Unsaturated Trimethylsilyl Esters: An Efficient and Practical Direct Synthesis of Unsaturated <i>β</i>-Hydroxy Acids
give exclusively the alpha-condensation products in excellent yields. The unsaturated beta-hydroxy acids thus obtained were directly identified, and the usual conversion into their methyl esters with diazomethane was not necessary. Unsaturated ketones underwent Michael reaction through alpha-addition leading to the unsaturated 5-oxo acids.
Synthesis of α-alkenyl-β-hydroxy adducts by α-addition of unprotected 4-bromocrotonic acid and amides with aldehydes and ketones by chromium(II)-mediated reactions
作者:Ludger A. Wessjohann、Harry Wild、Leonildo A. Ferreira、Henri S. Schrekker