Synthesis and Structure of Bicyclic Enediynes via twofold carbenoid ring closure

Abstract

Macrobicyclic enediynes were obtained in four steps from dicarboxylic diesters. The key step of the synthesis is a twofold carbenoid ring closing procedure from acyclic precursors. Crystal structure analyses showed that bicyclo[6.6.4]dienetetrayne is not strained. Thermal analysis revealed its low thermal reactivity. An attempt to obtain bicyclo[6.6.2]dienetetrayne structures using the same method failed.