GERMANONES ET GERMATHIONES: REACTIVITE VIS-A-VIS DE PETITS CYCLES ORGANIQUES

Article abstract of DOI:10.1016/S0022-328X(00)98729-1

Dialcoylgermanones and dialcoylgermathiones are generated from various germa-heterocyclic precursors and dimeric or trimeric forms (R2GeO)2 and (R2GeS)3.These species (X = O, S) react with various three- or four-membered rings (n = 2, Y = O, S, NR, CHCN; n = 3, Y = O, S) to lead to the germaheterocycles (X = O, S).Cyclogermathianes (R2GeS)3 lead very easily, by thermic and catalytic dissociation to the germathiones .Basic solvent (Et3N, HMPA) and catalysts <(Ph3P)2PdCl2> induce these dissociations.Mechanism and stereochemistry ofinsertion reactions of these transient species (X = O, S) into oxirane rings are established from cis- and trans-butene oxides.The formation of germanium hexacoordinated intermediate complex can explain the observed stereoselectivity.With germathiones the stereoselectivity derives from the strong nucleophilic activity of these species.