Highly Substituted 2-Amido-furans From Rh(II)-Catalyzed Cyclopropenations of Ynamides

Rh(II)-catalyzed cyclopropenations of ynamides are described. Although an actual amido−cyclopropene intermediate may not be involved, these reactions provide a facile entry to highly substituted 2-amido-furans, thereby formerly constituting a [3 + 2] cycloaddition. An application of these de novo 2-amido-furans in N-tethered intramolecular [4 + 2] cycloadditions is also illustrated, leading to dihydroindoles and tetrahydroquinolines.