Brominated vinyl ketene thioacetal, ene- and diene acetals; potential four-carbon synthons
作者:Samuel Braverman、Marina Cherkinsky、Eliahu Nov、Milon Sprecher
DOI:10.1016/s0040-4020(99)00028-9
日期:1999.2
prepared. In contrast to the reaction of dithioacetal 3, these acetals undergo either a single or double HBr elimination with formation of mono-olefins or cumulated diene, respectively. The mechanism of formation of the reaction products is discussed, and the reactivity of the novel per-functionalized tetrasubstituted 1,3-butadiene 1 with the strongly electrophilic dienophile PTAD is presented.
描述了一种新颖,方便的制备共轭乙烯基乙烯酮乙烯硫缩醛的方法:将CBr 4添加到丙烯醛中,然后在碱性条件下对相应的醛2进行硫缩醛化,然后在碱性条件下对3进行双脱氢溴化。为比较起见,三个O-缩醛4–还准备了6个。与二硫缩醛3的反应相反,这些缩醛经过一次或两次HBr消除,分别形成单烯烃或累积的二烯。讨论了反应产物的形成机理,以及新型的全官能化四取代的1,3-丁二烯1的反应性 提出了具有强亲电性的亲二烯体的PTAD。