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.
δ-烯丙氧基取代的δ,δ-²-不饱和酯 1a - r 是由市场上可买到的起始原料通过 5 个步骤制备而成的。合成的关键步骤是在δ-烯丙氧基取代酯 2a - i 和醛 R1CHO 之间进行醛醇加成,然后进行甲磺化和 DBU 介导的消去反应,得到 2-烷氧基羰基取代的烯丙基乙烯基酯 1a - r。Z:E 比率为 3:2-9:1。