stereogenic double bonds is described. A combination of the highly Lewis acidic [Cu(S,S)-tert-Bu-box}](H2O)2(SbF6)2 complex and molecular sieves served as catalyst and afforded the Claisen rearrangement products, substituted and functionalized α-keto esters, in high yield with a remarkable diastereo- and enantioselectivity. The influence of ligand structure, counterion and allyl vinyl ether double bond configuration
Synthesis of α-Allyloxy-Substituted α,β-Unsaturated Esters via Aldol Condensation. Convenient Access of Highly Substituted Allyl Vinyl Ethers
作者:Martin Hiersemann
DOI:10.1055/s-2000-6424
日期:——
α-Allyloxy-substituted α,β-unsaturated esters 1a - r have been prepared in 5 steps from commercially available starting materials. The key sequence of the synthesis is an aldol addition between an α-allyloxy-substituted ester 2a - i and an aldehyde R1CHO followed by mesylation and DBU mediated elimination to afford the 2-alkoxycarbonyl-substituted allyl vinyl esters 1a - r. The E/Z ratio of the newly generated vinyl ether double bond is apparently determined by the steric bulk of the vinyl ether double bond substituent R1. Z:E ratios from 3:2-9:1 were obtained.