Reduction of bis(phosphonio)isophosphindolides to phosphane-functionalizedbenzo[c]phospholides

Bis(phosphonio)benzo[c]phospholides (isophosphindolides) 1a,b have been fou nd to react with magnesium or alkali metal naphthalenides MC10H8 (M = Li, N a, K) with reduction of one or both of the phosphonio groups. The main prod ucts are the mono- or bis(phosphanyl)-substituted heterocycles 2, 3, 6, 7, which have been characterized by in situ NMR studies and in some cases isol ated. Subsequent reaction of 2 with excess [Ni(CO)(4)] gave the complex 4, which has been characterized by X-ray diffractometry. Reactions of la with alkali metals followed a more complicated course and gave a mixture of 2, 3 , and the substitution product 8, which was further reduced to the phosphan ido-substituted benzo[c]phospholide 9. The latter could be formed selective ly by first converting 1a into 8 by treatment with PhNa and then treating t his with lithium. NMR data of the phosphane-substituted benzo[c]phospholide s and the structural features of 4 are discussed.