A copper-catalyzed one-pot multicomponent protocol has been developed for construction of spiro heterocycles. The domino approach leads to the synthesis of spiro oxazolidinones starting from ketones, arylacetylenes, and isocyanates via catalytic addition, hydroamination, and cyclization involving consecutive C−C, C−O, and C−N bond formations.

A facile, rapid, metal-free regioselective halogenation and thiocyanation of imidazo[1,2-a]pyridine/pyrimidine heterocycles has been achieved under solvent-free reaction conditions. Halogenations and thiocyanation of the heterocycles could be accomplished by simple grinding of reactants and hypervalent iodine reagents with the corresponding alkali metal or ammonium salts. The method has been extrapolated to a cleaner synthesis of brominated imidazo[1,2-a]pyridine/pyrimidine derivatives, starting from the corresponding heterocyclic amines and substituted α-bromoketones, utilising HBr generated in situ as the source of bromine.

An efficient one-pot synthesis of quinazolino[4,3-b]quinazoline derivatives has been accomplished, starting from 2-(2-bromo­phenyl)quinazolin-4(3H)-one, aldehydes, and various nitrogen sources under aerobic conditions. The multicomponent protocol is mediated by copper(I) salts and involves amination of 2-(2-bromophenyl)quinazolin-4(3H)-one, followed by condensation with the aldehyde and an oxidative cyclization to give the target compounds in moderate to good yields.