Regio- and stereoselective addition of bronsted acids to yndiamides: synthesis of N,O,N-and N,S,N-trisubstituted ketene acetals

Yndiamides, N, N-disubstituted alkynes, are versatile building blocks for the synthesis of nitrogen-containing organic molecules. Unlike ynamides, relatives that are inherently polarized by a single nitrogen substituent, their pseudo-symmetric nature renders regioselective reactions challenging. Here we report investigations into the regioselective addition of Bronsted acids to non-symmetric yndiamides, a reaction that delivers N, O, N- and N, S, N -trisubstituted ketene acetals with excellent regio- and stereoselectivity.