(2,5)-Ene Cyclization Catalyzed by Mesoporous Solid Acids: Isotope Labeling Study and ab Initio Calculation for Continuum from Concerted to Stepwise Ene Mechanism
作者:Koichi Mikami、Hirofumi Ohmura、Masahiro Yamanaka
DOI:10.1021/jo020634j
日期:2003.2.1
by mesoporous solid acids are reported from the mechanistic point of view. The continuum (2,5)-ene mechanism from the concerted to the cationic cyclization followed by 1,2-hydride shift is evaluated. The solid-acid-catalyzed cyclization of the oxonium ion intermediate 4 derived from cyclic allylic lactol ether 3 bearing allylic hydroxy group affords the (2,5)-ene product as the enol form, eventually
从机理的观点报道了由中孔固体酸催化的(2,5)-烯反应。评估了从协同到阳离子环化再到1,2-氢化物移位的连续性(2,5)-烯键机理。带有烯丙基羟基的环状烯丙基乳醇醚3衍生的氧离子中间体4的固酸催化环化反应提供(2,5)-烯产物为烯醇形式,最终互变异构为相应的醛6。目前,在氧烯离子中间体(如4)的烯环化过程中,实验和理论上都证实了逐步机理的协调性。由于β-稳定化,因此显示出导致醛6的逐步环化与协同反应相关联。羟基碳鎓离子中间体。