Alkylation alkoxide

A. Fidalgo, R. Ciriminna, L. M. Ilharco and M. Pagliaro, Role of the Alkyl-Alkoxide Precursor on the Structure and Catalytic Properties of Hybrid Sol-Gel Catalysts, Chem. Mater., 2005, 17, 6686. 

Nucleophilic Substitution Alkyl, Alkoxide/Phenoxide, Halides and Amido... 

The carbonyl group of formaldehyde is highly susceptible to nucleophilic attack and this monomer can be polymerized with almost any base. Metal alkyls, alkoxides, phenolates, and carboxylates, hydrated alumina, amines, phosphines, and pyridine are effective in polymerizing formaldehyde. 

Seebach and coworkers have developed an extensive chemistry of mixed alkyl alkoxides of titanium and zirconium and their usefulness towards a number of organic synthetic problems has been demonstrated.107,108... 

Alkyl/alkoxide metathesis employing OfBu as alkoxide component revealed to be even more complicated and unpredictable [222-224]. The reactivity of well-characterized (CpR)3 Ln(OtBu)/ species towards alkali metal alkyls seems to be quite sensitive to specific reaction conditions, including choice of solvent, number and type of cyclopentadienyl co-ligands or reaction temperature. 

The magnitude of the t2g - 2eg energy gap is primarily determined by how much 2Cg is destabilized by the ligand a donor set. When the ligands are strong a donors (e.g. PR3, CO, alkyl, alkoxide, alkene), then 2eg lies at a very high energy and... 

In connection with the mechanistic interpretations of stereocontrol, either (LXII) or (LXIII) is consistent with the effect of a bulky alkoxide group. This is because alkyl-alkoxide exchange reactions could place an alkoxide group on aluminum where growth occurs. Structure (LXIII) seems reasonable in view of the known tendency of aluminum alkoxides to dimerize (McElvain and Davie, 1951 Hoffmann, 1960) however, a monomeric structure (LXII) cannot presently be excluded. The metal alkoxides, like alkyllithiums, probably involve equilibria among monomeric and associated species. Therefore, one or more active species may be involved. Whatever the species, it is not too difficult to imagine a complex composed of a tetravalent aluminum, in which monomer-chain or monomer-chain-alkoxide interactions favor one path for monomer addition. 

Growth at an aluminum-carbon bond is conceivable if alkyl-alkoxide exchange occurred [Eq. (45)]. This assumes that the... 

The volatile metal or semimetal compounds used as precursors in ALE can be selected from a wide range of compounds including metal chlorides, P-diketonates, alkyls, alkoxides, and metallocenes etc. [16,17]. The precursor can be liquid, solid, or gas at room temperature and must be stable enough to withstand heating. It should also be free of impurities that volatilize below or at the temperatures used in the processing. Often moisture is the most serious impurity, and the compound should be dried before use. Any solvent coordinated to metal compounds such as P-diketonates needs to be removed. 

The reaction of (dppe)PtMe(OMe) (dppe = bis(l,2-diphenylphosphino)ethane) with F2C=CF2 has been shown to give (dppe)PtMe(CF2CF20Me), providing the first example of an alkene insertion into an M-OR bond. Interestingly, the platinum alkyl-alkoxide complex does not react with ethene or pentene but similar to 4-tetrafluoro-ethylene other activated alkenes such as acrylonitrile and methylacrylate also undergo insertion reactions. It is noteworthy that the reaction does not involve nucleophilic attack on a coordinated alkene by free methoxide ion. The transformation of a M-OR bond into a M-R bond appears to be thermodynamically favourable in this instance. 

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