Nouveaux oxamétallocycloalcanes (VII) Synthèse de (germa‐, sila‐, et stanna‐)dioxacycloalcanes et alcènes par insertion de dérivés carbonylés sur la liaison métal‐oxygène d'éthers cycliques organométalliques

Abstract

sila-, et stanna-)dioxacycloalcanes et alches par insertion de dkriviis carbonylb sur la liaison mktal-oxygthe d'kthers cycliques organomktalliquesThe insertion reactions of carbonyl derivatives such as acetaldehyde, chloral, hexachloro-and hexafluoro-acetone on the metal-oxygen bond of alkoxyorganometallic compounds have been studied in the case of numerous cyclic ethers containing silicon, germanium or tin atoms in the ring. These reactions proceed by ring expansion leading to the formation of cyclic acetals : germaoxetanes yield 4-germa-l,3-dioxanes, (sila-, germa-or stanna-) oxacyclopentanes give 1,3-dioxacycloheptanes and (germa-or stanna-) oxacyclopentenes lead to 1,3-dioxacycloheptenes with the group IV element in position 4.The mechanism of these insertion reactions is discussed according to the nature of carbonyl derivatives and metal heteroatom in the starting cyclic compounds, as well as catalytic and solvent effects.

A Synthetic Equivalent of a Germanone Derivative

“…Nevertheless up until recently only indirect evidence was available to suggest their transient existence. [2][3][4][5][6][7][8][9][10] Many starting materials leading to these highly elusive species are often heterocycles with a germanium-oxygen linkage: 2-germaoxetanes, [1,4] 2-germa-1,5-dioxanes, [11] various seven-membered rings, [12] oxazagermetanes [8a] and dioxagermetanes. [9] Other sources of transient germanones include the thermal decomposition of germanium oxides [7,12] or germa-epoxides [7] and oxidation of germylenes.…”

Synthetic and mechanistic studies of (p-p) pi-bonded organosilicon and organogermanium reactive intermediates

“…The silanone was trapped by the usual silanone traps such as dimethyldimethoxysilane and Dy The example of silanone insertion into a silicon-chlorine bond was also reported. When the Diels-Alder reaction was run in the presence of trimethylchlorosilane, chloropentamethyldisiloxane (65) and 1-chloroheptamethyltrisiloxane (66) were formed. Products ^ and 66 were postulated to arise via insertion of dimethylsilanone into trimethyl chlorosilane.…”