N-Acylation of Oxazolidinones via Aerobic Oxidative NHC Catalysis
In the ongoing quest to find alternatives to atom un-economical and forcing conditions in acylation reactions, aerobic oxidative NHC catalysis has emerged as a method to convert aldehydes to potent acylating reagents. This strategy has been utilized in the esterification of alcohols but not yet been shown for densely polyfunctionalized N- heterocycles such as, oxazolidinones and pyrrolidinones. Conventional acylation of oxazolidinones are typically associated with forcing reaction conditions, requiring separate activation steps and strong bases, which does not adhere to the principles of green chemistry. For reasons of waste prevention, atom economy, less hazardous syntheses and reduction of derivatives finding alternative methods are desirable.
In this manuscript, we demonstrate the synthesis of several N-acylated oxazolidinones and pyrrolidinones that are chemically relevant, both found as pharmaceuticals and natural products as well as auxiliaries for synthesis. The developed method operates at room temperature and can be performed in ethyl acetate with open reaction vessels. The substrate scope is broad, with products isolated in good to excellent yields. The functional group tolerance is exemplified with 22 entries, where different aldehydes, oxazolidinones and pyrrolidinones are systematically investigated. Moreover, the reaction is clean as water is generated as the only byproduct.