Three-Component One-Pot Construction of 2-Aryl-4 H -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-4 H -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.