Synthesis of o -Carborane-Fused Pyrazoles through Sequential C-N Bond Formation.

Transition-metal-free synthetic method for o -carborane-fused pyrazoles as a new scaffold has been developed from the reaction of B(4)-acylmethyl or B(3,5)-diacylmethyl o -carborane with 2-azido-1,3-dimethylimidazolinium hexafluorophosphate (ADMP) in the presence of DBU in acetonitrile through sequential diazotization and cyclization reaction in one pot, consequently allowing twofold C-N bond formation under extremely mild conditions and high functional group tolerance.