New intra–intermolecular criss-cross cycloaddition of unsymmetrical allenylazines with alkynes leading to three fused five-membered heterocycles

This report describes a new type of intra–intermolecular criss-cross cycloadditions. Thermal reactions of unsymmetrical allenylazines in the presence of alkynes led to three fused five-membered heterocycles in some cases. In the case of unsymmetrical substituted alkynes, a regioselectivity was observed. The molecular structures of all products are discussed. One X-ray crystal structure is also reported.