Alkynylphosphonates are an important class of organic compounds. They are excellent precursor for important transformations such as conjugate addition, cycloaddition, metellacycle, and hydration. Some of the alkynylphosphates containing molecules are also found to be bioactive and hence medicinally important. The conventional procedure for the synthesis of alkynylphosphonates includes the use of nucleophilic substitution reactions involving toxic and moisture sensitive P(O)X compounds with metal acetylides under harsh conditions. But these procedures suffer from low functional group tolerance and use of hazardous conditions. Other methods for the synthesis of alkynylphosphonates involves the use of functionalized alkenes such as 1,1-dibromoalkenes, alkynyl sulfones, copper acetylides, and propiolic acids. In the last decade, the use of atom-efficient methods has been the area of great interest and one of the straightforward atom efficient methods for the synthesis of alkynylphosphonates is the direct cross coupling between P(O)-H compounds and terminal alkynes. Scheme 2 Ni-catalyzed synthesis of alkynylphosphonates Last year, Han group reported the Ag free palladium-catalyzed dehydrogenative phosphorylation of terminal alkynes with hydrogen phosphine oxides. A good tolerance of functional group on alkynes was also reported. Although elegant protocols have been reported in the last few years for the synthesis of alkynylphosphonates, but the use of non-precious metals such as nickel has never been used for the synthesis. In the current project, we are exploring the use of nickel salts and nickel complexes in presence of various phosphorus ligands for the synthesis of alkynyl phosphonates (Scheme 2).

Nickel catalyzed synthesis of alkynylphosphonates

2019 Fall National Meeting

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