Wagner-Meerwein studies

Cram, D. Studies in Stereochemistry. I. The Stereospecific Wagner-Meerwein Rearrangement of the Isomers of 3-Phenyl-2-butanol. J. Amer. chem. Soc. 71, 3863 (1949). 

Acid-induced wagner-meerwein rearrangements in chiral alcohols. In view of the considerable interest on ion-molecule complexes involved in gas-phase analogues of solvolytic reactions," ° " a sustained research effort has been directed to the study of Wagner-Meerwein rearrangements in cationized )8-arylaIkyl systems, under conditions excluding nucleophilic assistance by the solvent which in these systems normally interferes with anchimeric assistance of groups adjacent to the... 

The structures found for the products of the various reactions are often themselves of interest for example, the many cases where the olefin group becomes attached to the metal by a metal-carbon a-bond form a useful body of knowledge, and structural studies have proved an apparent case of the Wagner-Meerwein rearrangement in Pt(IV) and Au(III) complexes. 

Kirmse and Sollenbohmer69 studied the trifluoroethanolysis of the norbomyl p-nitrobenzoate 57, and observed the formation of the intermediate 58, followed by a 6,2 migration of silicon and Wagner-Meerwein shifts to give a mixture of products. The solvolysis of the norbornyl system 57 is accelerated by a factor of 3 x 104 compared to unsubstituted 2-norbornyl p-nitrobenzoate. 

For a review of the Wagner-Meerwein reaction in a fundamental study on equilibria of different ring sizes, see ref. [5],... 

Further studies on the isomeric dichlorides of (47) with different Y and Y substitution support the proposal that an electron transfer occurs from the photoexcited n orbital of the aromatic ring to the a orbital of the carbon-chlorine bond [72], When Y = H and Y = CN, COCH3 or N02 no photosolvolysis or photo-Wagner-Meerwein rearrangements were observed. Using the Weller equation it was determined that electron transfer from the presumed triplet states of the COCH3 or N02 substituted compounds or the singlet state of... 

Cristol and his colleagues have contributed greatly to the understanding of the photochemical transformations of compounds which undergo light-induced solvolysis and photo-Wagner-Meerwein reactions. There are several other studies which are important additions to this body of work which are not covered in this review, and we refer the reader to these references [78-83]. 

Detailed studies have been made of metal-mediated Wagner-Meerwein rearrangements in dicobalt, dimolybdenum, and cobalt-molybdenum complexes of the 2-fenchyl cation.105... 

A Wagner-Meerwein-type rearrangement of the cation has been often observed in the oxidation of carboxylic acids (equation 59). The relative migratory aptitude of R and R has been studied, and this type of rearrangement has been applied to the synthesis of )-muscone (equation 60). ... 

The norbornyl cation is at the heart of the nonclassical ion problem . The argument over the stable cation concerns whether it is a rapidly equilibrating pair of classical ions or rather a symmetrical ion (Brown, 1977). The isotopic perturbation studies by Saunders and Kates (1980) show that the postulated rapid Wagner-Meerwein rearrangement (4) is not consistent with the results but is a static structure like [4],... 

The proposed transition states have been supported by deuterium isotope studies Evidence such as the decomposition behaviour in solution and the nature of the increases in the rates of decomposition along the series of chloro-formates methyl, ethyl, isopropyl, 2-butyl, /-butyl suggests that the transition states are somewhat polar °> . Lewis and Herndon found 2-methylbut-1-ene and 2-methylbut-2-ene as the olefinic products of the elimination reaction of neopentyl chloroformate, and the kinetic evidence supports a Wagner-Meerwein rearrangement in the gas-phase as in the case of neopentyl chloride pyrolysis (refs. 407, 408, 566). 

Pachuau, Z., Lyngdoh, R. H. D. Moiecuiar orbitai studies on the Wagner-Meerwein migration in some acyclic pinacol-pinacolone rearrangements. J. Chem. Sci. (Bangalore, India) 2004, 116, 83-91. 

Since the initial studies by Wagner at the turn of the century, the Wagner-Meerwein rearrangement has been the subject of almost continuous investigation. The reaction was initially examined in terms of the rearrangement of a-pinene (1) to bomyl chloride (2 Scheme 1), and of camphene (3) via camphene hydrochloride (4) to isobomyl chloride (5). 

Rearrangements of carbocations also may be. studied by NMR methods. The norbornyl cation (5-26) may undergo 3,2- and 6,2-hydride shifts, as well as Wagner-Meerwein (W-M)... 

This high-potential quinone is second in effectiveness to 2,3-dichloro-5,6-dicyano-1,4-benzoquinone in the dehydrogenation of tetralin, acenaphthene, and dibenzyl in benzene at SO"." Kinetic studies are reported. The dehydrogenation of the 1,1-dimethyltetralin is attended with Wagner-Meerwein rearrangement ... 

The spectrum was interpreted as evidence that the 3,2-hydrogen shift was frozen out, but the 6,1,2-hydrogen shift and the Wagner-Meerwein rearrangement are still fast even at the low temperature used (—120 °C). The rate of the slow 3,2-hydrogen shift was established from temperature-dependence studies, by comparing experimental spectra with those calculated for different rates. The activation energy of this shift is 10.8 0.6 kcal/mol, with A = 1012 3 sec-1 21 ... 

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