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

The functionalization of aryl and heteroaryls using α-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 α-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.

Synthesis of the tricyclic core of manzamine A.

An efficient synthetic approach to the core structure of the manzamine alkaloids is reported, particularly in relation to incorporating a one-carbon unit in ring B from which the aldehyde in ircinal A or the beta-carboline unit in manzamine A could potentially be generated. The key steps involve a Johnson-Claisen rearrangement, enolate alkylation, dithiane alkylation and a stereoselective intramolecular dipolar cycloaddition of an azomethine ylide, which provided the desired tricyclic ABC core structure.

Palladium-Catalyzed Synthesis of Bis-Substituted Sulfoxonium Ylides.

The lack of general access to bis-substituted sulfoxonium ylides is addressed by developing a palladium-catalyzed C-H cross-coupling of α-ester sulfoxonium ylides with (hetero)aryl iodides, bromides, and triflates. Three different catalysts have been evaluated. This method is amenable to the late-stage functionalization of active pharmaceutical ingredients.