Cesium Carbonate Catalyzed Esterification of -Benzyl--Boc-amides under Ambient Conditions.

We report a general activated amide to ester transformation catalyzed by CsCO. Using this approach, esterification proceeds under relatively mild conditions and without the need for a transition metal catalyst. This method exhibits broad substrate scope and represents a practical alternative to existing esterification strategies. The synthetic utility of this protocol is demonstrated via the facile synthesis of crown ether derivatives and the late-stage modification of a representative natural product and several sugars in reasonable yields.