An Intramolecular 2 + 3 Cycloaddition Route to Fused 5-Heterosubstituted Tetrazoles

reaction: see text Fused 5-heterotetrazole ring systems are synthesized in high yield via intramolecular 2 + 3 cycloadditions of organic azides and heteroatom-substituted nitriles. Cyanates, thiocyanates, and cyanamides are all competent dipolarophiles for this reaction. A variety of scaffolds are tolerated when the new enclosed ring is five- or six-membered.