Flexible synthesis of phosphorus(V)-substituted 1,3,4-thiadiazoles and pyridazines

Heterocyclic organophosphorus compounds have remarkable properties and a great deal of potential to meet contemporary societal demands regarding health, environment, energy, and information technologies. Here, we report highly reactive phosphorylthioformic acid hydrazides as novel polyheteroatom reagents for the concise synthesis of phosphorus -substituted medium-ring aza-heterocyclic systems. The reaction of phosphorylthioformic acid hydrazides with functionalized aldehydes was systematically investigated. Chemoselective and flexible synthetic approaches to phosphorus(V)-substituted 1,3,4-thiadiazoles, 1,3,4-thiadiazolines, and pyridazines were developed. Phosphorylthioformic acid hydrazides proved to be useful for the preparation of phosphorus(V)-containing heterocyclic steroid derivatives.