N-Carbamate α-aminoalkyl-p-tolylsulfones—convenient substrates in the nitro-Mannich synthesis of secondary N-carbamate protected syn-2-amino-1-nitroalkanephosphonates

An efficient one-pot synthesis of secondary N-carbamate protected syn-β-amino-α-nitroalkanephosphonates using diethyl nitromethanephosphonate and N-Boc or N-Cbz imines, generated in situ from stable N-Boc or N-Cbz α-aminoalkyl-p-tolylsulfones has been developed under PTC conditions. A model enantioselective version of this reaction is also described. Enantioselectivity up to 67% ee is achieved using a chiral thiourea catalyst derived from a cinchona alkaloid. Completely stereoselective conversion of the title compounds into partially N-carbamate protected syn-1,2-diaminoalkanephosphonates has also been elaborated.