Preparation of α-aminophosphines on solid support: model studies and parallel synthesis

On-resin assembly of phosphine ligands represents a formidable challenge. Following model solution studies, we developed two synthetic routes for α-aminophosphine synthesis on solid support. The ligands are prepared via the Mannich reaction of the resin-bound aldehyde, amine and diphenylphosphine with very good yield and purity. Alternatively, the amine can serve as the anchoring building block. The ligands were qualitatively and quantitatively analyzed using gel-phase 31P and 13C NMR techniques. The studies culminated in the parallel synthesis of a 40-member library of borane-protected α-aminophosphines.