One-Step Construction of 2-Methylquinazolin-4(3<i>H</i>)-ones Using Solid Calcium Carbide as an Alternative to Gaseous Acetylene

2-Methylquinazolin-4(3<i>H</i>)-ones were efficiently constructed using solid calcium carbide as an alkyne source, 2-aminobenzamides or 2-aminobenzohydrazides as substrates, and <i>p</i>-tolylsulfonyl azide as a mediator through simultaneous formation of two C-N bonds in one step. The salient features of this protocol are the use of an inexpensive, abundant and easy-to-use alkyne source as a substitute for flammable and explosive gaseous acetylene, low-cost catalyst, wide substrate scope, satisfactory yield, and simple manipulation. This method can also be extended to gram scale.