The phospha-Brook rearrangement of dialkyl 1-aryl-1-hydroxymethylphosphonates
(HPs) to the corresponding benzyl phosphates (BPs) has been elaborated
under solid–liquid phase transfer catalytic conditions. The best procedure involved the use
of triethylbenzylammonium chloride as the catalyst and Cs2CO3 as the base in acetonitrile
as the solvent at room temperature. The substrate dependence of the rearrangement has
been studied, and the mechanism of the transformation under discussion was explored by
quantum chemical calculations. The key intermediate is an oxaphosphirane. The one-pot
version starting with the Pudovik reaction has also been developed. The conditions of this
tandem transformation were the same, as those for the one-step HP→BP conversion.
Keywords: α-hydroxyphosphonate, benzyl phosphate, phospha-Brook rearrangement, mechanism.
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