Synthesis of 1,2-Diphospholides Using a Main Group “Superbase”

The synthesis of a range of 1,2-diphospholides can be achieved by a one-pot procedure involving the reactions of aromatic primary phosphines bearing ortho-CH2 substituents with the superbase mixture of nBuLi/Sb(NMe2)3 in the presence of the Lewis base donor TMEDA (Me2NCH2CH2NMe2). The synthesis of the parent benzo-1,2-diphospholide and the substituted derivatives 4-methoxybenzo-1,2-diphospholide, 9-methylbenzo-1,2-diphospholide, and naphtho-1,2-diphospholide are reported from readily prepared primary phosphines. Bulk synthesis of the potassium salt of the previously reported 4,6-dimethylbenzo-1,2-diphospholide anion using this route provides a convenient starting material for reactivity studies.