Phosphane and Bis(phosphane) Ligands from Phosphinic Acids

The Boyd−Regan methodology allowed for access to various cyclic or benzylic mono- and bis(phosphinic acids) 1−6. The reduction of monophosphinic acids to secondary phosphanes 7−9 was achieved with silanes. On the other hand, reduction of the bis(phosphinic acids) with LiAlH4 led to bis(phosphanes) 12−13. Various cyclic phosphanes and bis(phosphanes) were obtained by the alkylation of these secondary phosphanes (as their borane adducts). The Michael addition of the same borane adducts to vinylic phosphonates led to phosphane−phosphonates which could be hydrolysed to new hydrosoluble phosphanes.