Switchable Synthesis of 2-Methylene-3-aminoindolines and 2-Methyl-3-aminoindoles Using Calcium Carbide as a Solid Alkyne Source.

The one-pot three-component method for the switchable synthesis of 2-methylene-3-aminoindolines and 2-methyl-3-aminoindoles by reactions of N -(2-formylaryl)sulfonamides, secondary amines, and calcium carbide is described. This protocol has the salient features of the use of an inexpensive, abundant, and easy-to-handle solid alkyne source, avoiding the use of flammable and explosive gaseous acetylene as an original alkyne source. In addition, a wide scope of substrates, satisfactory yield, and simple workup procedure are also advantages of this method.