Efficient strategy toward saturated N, P-heterocycles. Synthesis of l,2-azaphospholidines and extension to the preparation of azaphosphacane and azaphosphanane higher homologues

Access to a new family of saturated N, P-heterocycles is described. Allylphosphonochloridates react with primary amines through a single synthetic operation involving the formation of N-P and N-C bonds to afford l,2-azaphospholidines. The N-P bond formation/aza-Michael cyclization sequence is extended to eight-and nine-membered N,N,P-heterocycles. The first lines of a conformational study of diazaphosphacanes are described. DFT calculations allowed the identification of two diastereomers that display preferred boat-chair and twisted-boat-chair conformations.