A highly stereoselective transformation of carboxylic esters to trisubstituted olefins via cationic cyclopropyl–allyl rearrangement of sulfonates of cis-1,2-disubstituted cyclopropanols
作者:Dzmitry G. Kananovich、Alaksiej L. Hurski、Oleg G. Kulinkovich
DOI:10.1016/j.tetlet.2007.09.172
日期:2007.11
Methanesulfonates of readily available cis-1,2-disubstituted cyclopropanols on reaction with magnesium bromide in diethyl ether undergo cyclopropyl–allyl rearrangement to afford allyl bromides, with an (E)-trisubstituted double bond, as main products. The amount of the corresponding (Z)-isomers did not exceed 5% when the reaction was performed at 0 °C, and the major concomitant products were the regioisomeric
与溴化镁在乙醚中反应时,易得的顺式1,2,2-二取代的环丙醇的甲磺酸盐进行环丙基-烯丙基重排,得到具有(E)-三取代的双键的烯丙基溴,作为主要产物。当反应在0℃下进行时,相应的(Z)-异构体的量不超过5%,并且主要的伴随产物是区域异构的二级溴化物。与主要的(E)-二取代的烯丙基溴相比,后者对硫,磷和氢亲核试剂的反应性足够低,并且这些反应适合于立体选择性地制备三取代的烯烃。