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Please login to access the full content or check if you have access via Variation 1: (Triphenylphosphoranylidene)thioketene and -ketenimines, and Allenylidene Ylides by Addition to 1,1-Dichloro(hetero)alkenes

DOI: 10.1055/sos-SD-027-00847

Schobert, R.; Gordon, G. J.Science of Synthesis, (2004271043.

Phosphacumulene ylides 141 are prepared in good yields by the reactions of (methylene)triphenylphosphorane with geminal dihalides 140 (Scheme 50). The reactions, which require a (methylene)triphenylphosphorane to dihalide stoichiometry of 3:1 proceed via the corresponding phosphonium salts. These intermediates undergo rapid tandem transylidationdehydrohalogenations with excess starting (methylene)triphenylphosphorane, to afford (phosphoranylidene)ketenimines 141 (X=NR1) with 1,1-dichloroimines 140 (X=NR1; Y=Cl),[‌52‌] (phosphoranylidene)thioketene ylide 141 (X=S) from reactions with thiophosgene 140 (X=S; Y=Cl),[‌52‌] and (allenylidene)triphenylphosphoranes 141 (X=CR1R2) from reactions with electron-poor 1,1-dihaloalkenes 140 (X=CR1R2; Y=Cl, Br).[‌561‌] However, the ylide 141 (X=O) cannot be prepared by a reaction of (methylene)triphenylphosphorane with phosgene.[‌259‌]

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