Three-Component One-Pot Construction of 2-Aryl-4H-benzo[4,5]thiazolo[3,2-a]pyrimidines Using Solid Calcium Carbide as a Surrogate of Gaseous Acetylene

A concise method for the construction of 2-aryl-4H-benzo[4,5]thiazolo[3,2-a]pyrimidines using solid calcium carbide instead of gaseous acetylene as an alkyne source and 2-aminobenzothiazoles and aromatic aldehydes as substrates through one-pot three-component cascade reactions is described. The salient features for this protocol are the use of an inexpensive and easy-to-handle alkyne source, noble-metal-free condition, wide substrate scope and functional tolerance, satisfactory yield, and simple workup procedure.