Transition-metal-free [4 + 2] cyclocondensation of diaryliodonium salts accessing phenazine, phenothiazine, phenoxazine and dioxane derivatives

Abstract

We report here a versatile transition-metal-free synthesis of diverse heterocycles from novel ortho-fluorinated nitro-diaryliodonium salts. The protocol shows broad functional-group tolerance and supports late-stage derivatization, as demonstrated by the synthesis of antipsychotic drugs including propazine, diphenhydramine, chlorpromazine, and so on. Mechanistic studies reveal that the nitro group plays a crucial role in C–F bond cleavage, providing rapid access to dual-heteroatom heterocyclic scaffolds without toxic or costly catalysts.