First diastereoselective [3 + 2] cycloaddition reaction of diethyl isocyanomethylphosphonate and maleimides.

Bicyclic alpha-iminophosphonates were prepared via the first diastereoselective silver catalyzed [3 + 2] cycloaddition reaction of diethyl isocyanomethylphosphonate and diversely N-substituted maleimides. The reduction of the resulting imine by catalytic hydrogenation led to cyclic alpha-aminophosphonates, which are a-aminoester surrogates. The relative stereochemistry of the adducts was confirmed by X-ray crystallographic analysis of 4. The diastereoselectivity of the cycloaddition reaction was rationalised by theoretical studies.