Synthesis, proton and 13C NMR and reaction mechanism studies of novel isoindolones derivatives, obtained through TAWERS procedure.

A series of novel isoindolone derivatives (13-18) were prepared in goods yields by applying the TAWERS methodology. A general approach for formation of isoindolones from the aza-Wittig reaction of iminophosphoranes with dialdehydes under neutral and mild conditions was realized. Using 1D NMR a [1,3]-hydride migration was detected.

13C and 1H NMR of 2,6-diaryl-1-hydroxy piperidin-4-one oximes; substituent effects on cis/trans ratio and conformational equilibria.

The reaction of substituted diarylidene acetones with hydroxylamine hydrochloride affords isomeric N-hydroxy diaryl piperidinone oximes as main products. The structures as well as conformational equilibria of these products were established by 1H and 13C NMR spectroscopy and further studied by variable temperature NMR. It was found that the cis/trans ratio of 2,6-substituted piperidine derivatives depended on the position of the substituent on the aromatic ring.