Quest for Even Higher Stabilized Foiled Carbenes

Foiled carbene structures comprising strong stabilizing interactions between the divalent carbon and the intramolecular double bond have been located by DFT calculations. These tetracyclic species bearing fused five-membered rings impeding intramolecular rearrangements are theoretically predicted to lie in a deep potential energy well. A suitable dibromocyclopropane precursor for this type of foiled carbene has been prepared in 12 steps. Its treatment with methyllithium led to the isolation of a product of a formal carbene dimerization, a bicyclopropylidene.通过密度泛函理论（DFT）计算，研究人员已确定受阻卡宾（foiled carbene）的结构：该类卡宾的二价碳与分子内双键之间存在强稳定相互作用。这类带有可阻碍分子内重排的稠合五元环的四环物种，经理论预测处于深势能阱中。针对该类受阻卡宾，科研人员已通过12步反应合成出适配的二溴环丙烷（dibromocyclopropane）前驱体。将该前驱体与甲基锂（methyllithium）反应后，成功分离得到形式上为卡宾二聚反应产物的双环丙叉（bicyclopropylidene）。