Quadruple Deprotonation of 2-Aminophenylphosphane with a p-Block-Metal/Alkali-Metal Base

摘要

The application of superbases,such as the well-known Schlosser base consisting of /BuOK and RLi,in the deprotonation of organic substrates is well established.[1] Recently,Mulvey investigated the structural chemistry and applications of related mixed-metal amide reagents.[2] These species show remarkable activity and specificity in their reactions with aromatic hydrocarbons and ferrocene (Cp_2Fe;Cp = cyclo-pentadienyl).[3'4] For example,the treatment of Cp_2Fe with a mixture of i'Pr_2NH/Bu_2Mg and nBuNa results in a double 1,3-deprotonation of the two Cp rings.[3] We recently observed that the stepwise reaction of MesPH_2 (Mes = 2,4,6-Me_3C_6H_2) with BnNa (Bn = benzyl) and [Sn(NMe_2)_2] results in the unusual stannate ion [Sn(2-CH_2-4,6-Me_2C_6H_2)(PMes)]_3",which arises from the intermolecular deprotonation of a methyl group (Scheme I).'51 We wanted to examine the activity of this type of p-block-metal/alkali metal reaction system further because this Sn'VBnNa system effectively acts as a superbase and there is a close relationship between this C-H activation reaction and activation reactions mediated by transition metals.[6] Herein,we present the observation that the reaction of 2-aminophenylphosphane (1-PH_2-2-NH_2C_6H_4) with "BuLi (1 equiv) followed by the addition of [Sn(NMe_2)_2] (1 equiv) results in remarkable quadruple deprotonation of the ligand (Scheme 2) and generates the unusual paramagnetic Sn"-centered cage [{[Sn(L)(NMe_2)Li(thf)][Sn(L)Li-(thf)_3]Sn}_2] (1) containing L~(4-) and L~(3-) ions (L = ligand;see the Experimental Section).