Rearrangements, oxidative

Ketones are rearranged oxidatively by reaction of the corresponding enols with thallium(III), e.g. to yield pyrroleacetic acids from acetyl pyrroles (G.W. Kenner, 1973 B W. Rotermund, 1975). 

The alkyne-cobalt carbonyl complex 3 formed from the alkyne 1 and dicobalt octacarbonyl 2 should lose at least one of the GOs on the metal to provide the vacancy for the incoming olefins. Subsequently, an olefin-bound complex 5 rearranged oxidatively to yield a metallacyclic intermediate 6. Migratory insertion of GO of 6 would provide the homologated ring intermediate 7, and the following two successive reductive eliminations afford the cyclopentenone... 

IPP and DMAPP lead to geranylpyrophosphate (GPP), which is an immediate precursor of monoterpenes. The formation of nerylpyrophosphate (NPP) from GPP gives rise to a wide range of acyclic, cyclic, bicyclic or tricyclic skeletons. Reactions like rearrangement, oxidation, reduction and hydration via various terpene cyclases result in the formation of numerous terpene derivatives. Condensation of GPP and IPP leads to farnesylpyrophosphate (FPP), the immediate precursor of sesquiterpenoids. Likewise, FPP and IPP are conducive to diterpenoids. 

Exercise 2-2 Classify each of the following reactions as a substitution, addition, elimination, rearrangement, oxidation-reduction, or acid-base proton-transfer reaction ... 

In a real system many reactions that fit into the general categories represented by 8.13 to 8.15 are possible. This is because the organic intermediates and products themselves may undergo further rearrangement, oxidation, and other reactions. Mechanistic studies for these reactions are therefore invariably based on kinetic models. In these models a set of reactions and associated rate constants are assumed. Through simulation and optimization methods the model is then refined so that best fit between observed and predicted data points are obtained. 

A domino palladium(II)-mediated rearrangement/oxidative cyclization of /3-aminocyclopropanoLs has been reported by Brandi and co-workers lead-... 

The 26 chapters, written by experts from 14 countries, cover a wide spectrum of topics related to the chemistry of enamines, including theory, structural chemistry, spectral properties, formation, reactions and stereochemistry, acidities, rearrangements, oxidation and reduction, as well as other topics. In two chapters, the material related to enamines was meagre. Hence, the chapter on radiation chemistry also deals with compounds with non-conjugated C=C and amino groups, and the chapter on synthesis and uses of isotopically labelled enamines includes enamines in which the nitrogen is part of a heterocyclic system. 

Substiluled acrylic acids a-methylene-y-butyrolactones. The reaction of 1 with the allylic alcohol 2 at 170° gives the product (3) of Claisen ortho ester rearrangement. Oxidative elimination of GsHsSeOH gives the 2-substituted acrylic ester 4. 

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