Tandem carbonyl coupling-rearrangements promoted by the niobium(III) reagent. Dual reductive and Lewis acid properties of NbCl3(DME)
作者:Jan Szymoniak、Jack Besançon、Claude Moïse
DOI:10.1016/s0040-4020(01)88467-2
日期:1992.1
properties of the reagent used. Starting from 1a stereospecific acetalization leads to threo-2,4,5-triphenyl-1,3-dioxolane (3a), whereas 3,3-diphenyl-2-butanone (7) is obtained from 6 in a pinacol-pinacolone type rearrangement. Alkenes may also be formed in the competing, temperature controlled deoxygenation The stereoselectivity and the easy control of NbCl3 (DME) mediated reactions make it a promising reagent
苯甲醛(1a)和苯乙酮(6)被显示通过NbCl 3(DME)进行高度立体选择性的还原偶联。当反应在-10℃下进行时,可以分离苏糖醇。由于所用试剂的路易斯酸性质,中间体新生物松子醇显示出后续转化的能力。从1a立体定向缩醛化开始,会产生苏-2,4,5-三苯基-1,3-二氧戊环(3a),而3,3-二苯基-2-丁酮(7)是从6品中获得频哪醇-频哪酮型重排。竞争性,温度控制的脱氧反应中也可能形成烯烃。立体选择性和NbCl 3的易控制性 (DME)介导的反应使其成为用于进一步合成应用的有前途的试剂。