Domino “Staudinger/Semi-Aza-Wittig/Fragmentation” Reactions of γ-Azido-β-hydroxyketones

Treatment of γ-azido-β-hydroxyketones with triphenylphosphine resulted, depending on the structural features of the starting materials, in a domino “Staudinger/semi-aza-Wittig/fragmentation” reaction rather than a normal aza-Wittig reaction. 2-Azido-1-hydroxy-1-(2,4-dioxoalkyl)cyclopentanes, readily available by condensation of 1,3-dicarbonyl dianions with 2-azidocyclopentanone, proved to be optimal starting materials for these reactions which afforded 1-(1,3-dioxoalkyl)amino-2-(alkylidene)cyclopentanes.