Zinc/Iron-Mediated Ring Opening of Dibromocyclopropanes for In Situ Diels-Alder Reactions with Electron-Deficient Aldehydes and Imines
作者:Florian Pünner、Gerhard Hilt
DOI:10.1002/ejoc.201300726
日期:2013.9
the carbonyl group of aldehydes, ketones, glyoxylic esters, or imines is necessary for the ring-opening reaction. The ring opening leads to a bromo-functionalized 1,3-diene, which then reacts in situ with the carbonyl group in a hetero-Diels–Alder reaction. The products are formed with high control of the regiochemistry and in good yields for electron-deficient aldehydes and imines, such as carbamates
二溴环丙烷可以通过使用催化量的二溴化锌和亚化学计量量的铁粉来开环。醛、酮、乙醛酸酯或亚胺的羰基的存在是开环反应所必需的。开环产生溴官能化的 1,3-二烯,然后在杂狄尔斯-阿尔德反应中与羰基原位反应。这些产品的形成对区域化学进行了高度控制,并且对于缺电子醛和亚胺(例如氨基甲酸酯)的收率很高。(E)-乙基2-(甲氧基羰基亚氨基)乙酸乙酯的应用导致了环状α-氨基酸衍生物。还报道了不对称二溴和二卤代环丙烷的使用。