Cyclopropanation vs. single-carbon insertion of pyrrole-2,3-diones with sulfonium ylides: synthesis of functionalized 2-azabicyclo[3.1.0]hexanes and pyridine-2,3-diones

Abstract

The method for the diastereoselective synthesis of pyrrole-annulated donor–acceptor cyclopropanes from pyrrole-2,3-diones and stabilized sulfonium ylides has been developed. Ring opening of these annulated cyclopropanes (spontaneous or Lewis acid/thermal mediated) leads to functionalized pyridine-2,3-diones with good yields and high functional group tolerance. The ring expansion of pyrrole-2,3-diones to pyridine-2,3-diones via sulfonium ylide insertion can be performed in a one-pot manner without isolation of the intermediate cyclopropane.