Chemospecific Cyclizations of α-Carbonyl Sulfoxonium Ylides on Aryls and Heteroaryls.

The functionalization of aryl and heteroaryls using alpha-carbonyl sulfoxonium ylides without the help of a directing group has remained so far a neglected area, despite the advantageous safety profile of sulfoxonium ylides. Described herein are the cyclizations of alpha-carbonyl sulfoxonium ylides onto benzenes, benzofurans and N-p-toluenesulfonyl indoles in the presence of a base in HFIP, whereas pyrroles and N-methyl indoles undergo cyclization in the presence of an iridium catalyst. Significantly, these two sets of conditions are chemospecific for each groups of substrates.