二氯二茂钛（III）介导的自由基诱导加成到Baylis-Hillman加合物：（E）-和（Z）-三取代烯烃以及α-亚甲基/亚芳基δ-内酯的合成

Titanocene(III) chloride mediated radical-induced addition to Baylis-Hillman adducts: synthesis of (E)- and (Z)-trisubstituted alkenes and alpha-methylene/arylidene delta-lactones.

作者信息

Mandal Samir K, Paira Moumita, Roy Subhas C

机构信息

Department of Organic Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, India.

出版信息

J Org Chem. 2008 May 16;73(10):3823-7. doi: 10.1021/jo800049p. Epub 2008 Apr 22.

DOI:10.1021/jo800049p

PMID:18426237

Abstract

Baylis-Hillman adduct underwent smooth radical-induced condensation with activated bromo compounds and epoxides using titanocene(III) chloride (Cp2TiCl) as the radical generator. The reactions of activated bromo compounds with 3-acetoxy-2-methylene alkanoates provided (E)-alkenes exclusively, whereas similar reactions with 3-acetoxy-2-methylenealkanenitriles led to (Z)-alkenes as the major product. The reactions of epoxides with Baylis-Hillman adduct furnished alpha-methylene/arylidene-delta-lactones in good yield via addition followed by in situ lactonization.

摘要

使用二氯二茂钛（Cp2TiCl）作为自由基引发剂，Baylis-Hillman加合物能与活性溴代化合物和环氧化物顺利发生自由基诱导的缩合反应。活性溴代化合物与3-乙酰氧基-2-亚甲基链烷酸酯反应仅生成（E）-烯烃，而与3-乙酰氧基-2-亚甲基链烷腈的类似反应则以（Z）-烯烃作为主要产物。环氧化物与Baylis-Hillman加合物反应，通过加成然后原位内酯化，以良好的产率生成α-亚甲基/亚芳基-δ-内酯。