Beckmann rearrangement of OTDP salts of oximes of aromatic ketones and synthetic applications

Article abstract of DOI:10.1016/S0040-4020(98)01122-3

Reaction between tris(dimethylamino)-phosphine, carbon tetrachloride and oximes of ketones leads to the corresponding Oximoxy-Tris-(Dimethylamino)- Phosphonium salts (OTDP salts), which are isolated in the form of hexafluorophosphates. These salts are solid and stable except if they are completely dehydrated. Their solutions, in non polar solvents like CHCl₃ , give Beckmann rearrangement at room temperature. The kinetics and mechanism have been studied by NMR. We have defined the conditions of trapping of the cationic intermediates formed in the rearrangement, leading to an effective synthesis of amidines and an access to a glycoside structure using the hemiacetalic hydroxyl group of sugar as nucleophile.