Copper-Catalyzed Domino-Double Annulation of o -Aminobenzamides with 2-Iodoisothiocyanates for the Synthesis of 12 H -Benzo[4,5]thiazolo[2,3- b ]quinazolin-12-ones.

A facile and efficient copper-catalyzed domino-double annulation strategy was developed from easily accessible o -aminobenzamides and 2-iodoisothiocyanates, which affords a direct pathway for the synthesis of tetracyclic fused 12 H -benzo[4,5]thiazolo[2,3- b ]quinazolin-12-ones in moderate to good yields without the addition of ligands, bases, and external oxidants. The reaction involves a C-N bond cleavage and the formation of a C-N/C-S bond in one step with the advantages of using an inexpensive copper catalyst and easy operation. Mechanistic studies suggest that this transformation proceeds via intermolecular condensation of o -aminobenzamides with 2-iodoisothiocyanates, followed by an intramolecular Ullmann-type cross-coupling cyclization reaction.