Synthesis of highly-functionalised pyridines via hetero-Diels–Alder methodology: reaction of 3-siloxy-1-aza-1,3-butadienes with electron deficient acetylenes
摘要:
The hetero-Diels-Alder reaction between 1-aza-3-siloxy-1,3-butadienes and electron deficient acetylenes is described. The reactivity of a range of alpha,beta-unsaturated oximes and hydrazones is assessed in the synthesis of tri- and tetra-substituted pyridines bearing an oxygen functionality at C-3. Microwave irradiation has been employed to decrease the extended reaction times and increase the poor yields often associated with this reaction. (c) 2006 Elsevier Ltd. All rights reserved.
Regioselective De Novo Synthesis of Cyanohydroxypyridines with a Concerted Cycloaddition Mechanism
作者:Jin-Yong Lu、John A. Keith、Wei-Zheng Shen、Markus Schürmann、Hans Preut、Timo Jacob、Hans-Dieter Arndt
DOI:10.1021/ja804078v
日期:2008.10.8
An efficient cycloaddition reaction of 1-alkoxy-1-azadienes with alpha,alpha-dicyanoalkenes is described, which gives facile access to highly substituted 3-hydroxypyridines in very good yields and with complete regiocontrol and chemoselectivity. The reaction path was investigated in detail by quantum mechanics calculations, reporting that a concertedcycloadditionmechanism and thermodynamic control