Spirophosphoranes derived from 3H-2,1-benzoxaphospholes

Abstract

Starting from lithium o-lithiobenzyl alkoxides and dichlorophosphines, a series of P-substituted 3H-2-1-benz-oxaphospholes has been prepared and converted into five-co-ordinate phosphoranes by addition of 4,5-dimethyl-o-benzoquinone or 4,4′-dimethylbenzil, or condensation with 4,5-dimethylpyrocatechol or pinacol. The variable-temperature n.m.r. spectra of these phosphoranes are discussed. In these systems phenylamino- and dimethylamino-groups have similar apicophilicities and are less apicophilic than hydrogen by some 4–5 kcal mol^–1.