Réactions des céténes et du dicéténe avec les germyl- et silylphosphines

Abstract

Ketenes add to germyl- and silylphosphines R 3MPEt 2 with opening of the carbonyl group and formation of phosphorylated alkenoxygermanes or -silanes ▪ (R′H, Ph). These adducts are thermally stable and only the addition derivative of diphenylketene and Me 3SiPEt 2 exhibits metallotropic isomerization to a C-derivative after prolonged heating. Hydrolysis of these addition compounds is a new approach to the acylphosphines R 2CH-CO-PEt 2. Diketene also reacts with germyl- and silylphosphines with acyloxygen bond cleavage and formation of metallated and phosphorylated ketoenolates of the type ▪. These derivatives isomerize either partially (MSi) or completely (MGe) into R 3MOC(CH 3)CHCOPEt 2. Their hydrolysis constitutes a new method of synthesis of the phosphorylated β-diketone ▪. The ketoenolates from the addition reaction of the hydrosilylphosphine, Me 2Si(H)PEt 2, cyclize readily after partial isomerization by the intramolecular addition SiH to CO, to give phosphorylated siladioxane and siladioxene. The conformation of these heterocyclic compounds has been studied.