NaOH-Catalyzed Thiolysis of α,β-Epoxyketones in Water. A Key Step in the Synthesis of Target Molecules Starting from α,β-Unsaturated Ketones
作者:Francesco Fringuelli、Ferdinando Pizzo、Luigi Vaccaro
DOI:10.1021/jo035804m
日期:2004.4.1
high yields (90−96%). The reactions of calchone oxide (10) with thiols 2b−d have exclusively resulted in the formation of β-carbonylsulfides 10b−d (82−93% yield), coming from the nucleophilic attack at the α-position and retroaldol condensation. To highlight the synthetic utility of this procedure, one-pot multisteps preparation of vinyl sulfides 7b and 7c, vinyl sulfoxides 12 and 13, and 1,5,6,7-tetrahydro-4H-1
NaOH(0.02-0.3摩尔当量)是α,β-环氧酮与烷基和芳基硫醇在水中硫解反应的有效催化剂。在温和的条件下(30°C和pH 6或9),具有完全的C-α-区域选择性和抗立体选择性,并完成了3,4-环氧庚烷-2-酮(1)与硫醇2a - d的硫解反应。抗-β-羰基-β-羟基硫化物3a - d的制备产率很高(95-98%)。化合物3a - d取决于其性质和pH条件,已发生脱水,C-3差向异构化反应和逆醛醇缩合。脱水抗-通过在70°C下进行原位酸性处理,化学选择性地进行了3a - d的反应,立体选择性地获得了相关的(Z)-乙烯基硫化物4,总产率为89-94%。下的NaOH催化硫解条件,环状α,β-环氧酮6 - 9只和自发脱水所示的C-α攻击,得到相应的乙烯基硫化物以高产率(90-96%)。氧化钙(10)与硫醇2b - d的反应仅导致β-羰基硫的形成10b - d(82-93%的收率)来自于α位的