Application of Aryl Siloxane Cross-Coupling to the Synthesis of Allocolchicinoids

In this communication, we report a new approach to the allocolchicine carbocyclic skeleton based upon an aryl siloxane coupling reaction and a phenanthrol ring expansion. These key steps allow for the selective functionalization of every carbon within the carbocyclic framework. The siloxane coupling-phenanthrol sequence was applied to the synthesis of two allocolchicinoids, including the first fully synthetic approach to N-acetyl colchinol-O-methyl ether (NCME).