Acyl transfer reactions metal catalysis

By far the most generally useful synthetic application of allyltributyltin is in the complementary set of transition metal- and radical-mediated substitution reactions. When the halide substrates are benzylic, allylic, aromatic or acyl, transition metal catalysis is usually the method of choice for allyl transfer from tin to carbon. When the halide (or halide equivalent) substrate is aliphatic or alicyclic, radical chain conditions are appropriate, as g-hydrogen elimination is generally not a problem in these cases. 

In the above aminolysis reactions, Mg2+ ion always activates P—O fission. Other divalent metal ions behave similarly. Change of nucleophile might result in the change of P—O to S—O fission. To pursue the possibility of metal ion catalyzed S—O fission under neutral conditions, we examined the catalysis of the Zn2+-pyridine-2-carboxaldoxime (Zn2+PCA) complex, since catalytic activity of this complex has been well known in some acyl and phosphoryl transfer reactions (18, 19, 20). However, the results described below again indicate that the complex promotes an exclusive P-O bond fission (21). 

The metallocarbene intermediates are most often formed from thermal, photolytic, or metal-catalyzed deconposition of diazocarbonyl compounds, with concomitant loss of dinitrogen. Under transition metal catalysis, the initially formed species is a metallocarbene rather than a free carbene, and this is usually desirable due to the moderated reactivity (and, hence, fewer undesired side reactions) of the metal-complexed carbene. The two most common methods for introduction of the diazo group are acylation of diazoalkanes with suitably activated carboxylic acid derivatives and diazo transfer reactions in the case of more acidic active methylene substrates fScheme 16.12T... 

Straeter, N., Lipscomb, W. N., Klabunde, T., and Krebs, B. "Two-Metal Ion Catalysis in Enzymic Acyl-and Phosphoryl-Transfer Reactions." Angew. Chem. hit. Ed. Eng., 35,2025 (1996). 

Straeter N, Lipscomb WN, Klabunde T, Krebs B. Two-metal ion catalysis in enzymic acyl- and phosphoryl-transfer reactions. Angew Chem Int Ed Engl. 1996 35 2375-2433. Wilcox DE. Binuclear metallohydrolases. Chem Rev. 1996 96 2435-2458. 

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