Catalytic transformation of carbon dioxide into seven-membered heterocycles and their domino transformation into bicyclic oxazolidinones
Wangyu Shi, Jordi Benet‐Buchholz, Arjan W. Kleij
Abstract
Converting carbon dioxide (CO2) into valuable heterocycles is of great synthetic value but is usually limited to five- and six-membered ring compounds. Here, we report a catalytic approach for transforming this carbon renewable into seven-membered heterocycles using a double-stage approach, combining a silver-catalyzed alkyne/CO2 coupling and a subsequent base-catalyzed ring-expansion. This methodology avoids the formation of thermodynamically more stable, smaller-ring by-products and has good functional group tolerance. The synthetic application of these larger-ring cyclic carbonates is further demonstrated by showing their unique ability to serve as synthons for the preparation of bicyclic oxazolidinone pharmacores through an intramolecular domino sequence that involves a transient ketimine group, and various other intermolecular transformations. The results described herein significantly expand on the use of CO2 as a cheap and versatile carbon feedstock generating elusive heterocycles and pharmaceutically relevant compounds. Converting carbon dioxide (CO2) into valuable heterocycles is of great synthetic value but is usually limited to five- and six-membered ring compounds. Here, the authors report a catalytic approach for transforming this carbon renewable into seven-membered heterocycles, combining a silver-catalyzed alkyne/CO2 coupling and a subsequent base-catalyzed ring expansion.