α-羰基烯酮环二硫代缩醛化学(Ⅵ)——β,β-1,3-亚丙二硫基-α,β-不饱和芳酮与烯丙基Grignard试剂加成物脱水反应的研究

The Chemistry of α-Oxo Ketene Cyclic Dithioacetals(Ⅳ)——Studies on the Dehydration of Adducts of β,β-1,3-Propylene-dithio-α,β-Unsaturated Arylketones with Allyl Grignard Reagents

提出了由β,β-1,3-亚丙二硫基-α,β-不饱和芳酮类化合物(1)与苄基氯化镁及烯丙基溴化镁加成所得的醇(2)在BF_3·Et_2O催化下脱水生成共轭烯烃(3)新的合成途径,合成了13种新化合物,结构经~1H N-MR、IR、UV及元素分析等确证.并对这一新合成途径的反应机制进行了讨论.

A new route for the synthesis of dialkylthio conjugated alkenes (3) has been developed. The addition of β,β-l,3-propylenedithio-α,β-unsaturated arylketones (1) with allyl or benzyl Grig-nard reagents afforded the carbinols (2). The carbinols (2) were converted to the alkenes (3) via dehydration catalyzed by BF3 · Et2O. The course of addition of benzyl Grignard reagents to (1) proceeds by regiospecific 1,2-pattern other than the sequential 1,4-, 1,2-addition, which might result from the hindrance of the rigid cyclic dithioalkyl group in (1), the mechanism and reaction condition are discussed. Thirteen new compounds are prepared, their structure are assigned by 1H NMR, IR and UV.