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From masked carbenes to heterocycles: Novel potentially biological active difluoromethylene phosphonates as versatile building blocks

Subject Area Organic Molecular Chemistry - Synthesis and Characterisation
Term from 2018 to 2022
Project identifier Deutsche Forschungsgemeinschaft (DFG) - Project number 391415715
 
Final Report Year 2022

Final Report Abstract

The phosphate moiety is a common structural fragment present in a wide range of biologically active compounds. In addition, α,α-difluoromethylenphosphonates are very important analogues of natural phosphates and have been found to be, for example, valuable enzyme inhibitors. Diazo compounds are, in turn, remarkably versatile building blocks in organic synthesis and their chemistry is still far from losing anything of its long-standing fascination and the inventory of methods for the preparation of a variety of diazo compounds is continuously supplemented by new methods and novel variations of established procedures. In this context, successful synthesis of a series of 2-diazo-1,1-difluoroalkyl phosphonates, upon diazotization of appropriate amines with tert-butyl nitrite in the presence of acetic acid, has been for the first time achieved. To exploit the rich chemistry of the diazo group as a versatile building block we subsequently used novel diazo derivatives in several different reactions, namely in O-H insertions with carboxylic, sulfonic acids and alcohols, cyclopropanation, Doyle-Kirmse rearrangement, [3+2] cycloaddition reactions as well as chlorination and aza-Wittig reaction. As a result, we were able to obtain a series of novel esters, cyclopropanes, sulfides, pyrazoles and pyrazolines possessing a difluromethyl phosphonate function. Unexpectedly, in the O-H insertion reaction of alcohols to 2-diazo-1,1,3,3,3-pentafluoropropyl phosphonate as well as in the aza-Wittig reaction with aryl 2-diazo-1,1-difluoropropyl phosphonates, α-fluorovinyl phosphonates were obtained as sole products. The presented chemistry opens the possibility for further modifications and application, especially in material or medicinal chemistry and represent an important achievement to the chemistry of fluorinated diazo molecules.

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