Synthesis of dimethylphosphorylamino diazo esters by a selective tandem Staudinger/Arbuzov rearrangement sequence of azido diazo esters with trimethylphosphite

γ-Azido-α-diazo-β-keto esters react selectively with trimethylphosphite by a tandem Staudinger/Arbuzov rearrangement sequence, furnishing γ-(dimethylphosphorylamino)-α-diazo-β-keto esters in good yield under mild conditions. Collected X-ray data for the novel diazo phosphoramides confirm the proposed chemoselectivity.