Migratory aptitude rearrangement

A. Nickon, New Perspectives on Carbene Rearrangements Migratory Aptitudes, Bystander Assistance, and Geminal Efficiency, Acc. Chem. Res. 1993, 26, 84. 

From the data eolleeted in Table VII, it follows that the migratory aptitude of the Si-, Ge-, and Sn-eentered groups in the rearrangement 40a 40b inereases from SiRj to SnRj groups. 

The carbocations generated by non-Kolbe electrolysis can rearrange by alkyl, phenyl or oxygen migration. The migratory aptitudes of different alkyl groups have been studied in the rearrangement of a-hydroxy carboxylic acids (Eq. 34) [323]. 

With unsymmetrical cyclic ketones, however, mixtures due to similar migratory aptitudes of the different groups are obtained (Table 13, Nos. 2, 3). The rearrangement has also been used as key step in a d,/-muscone synthesis (Table 13, No. 4). 

In order to answer the question about inherent migratory aptitudes, the obvious type of substrate to use (in the pinacol rearrangement) is R RC—CRR since the... 

It has been shown that methyl and phenyl have lower migratory aptitudes than hydrogen in thermal sigmatropic rearrangements Shen, K. McEwen, W.E. Wolf, A.P. Tetrahedron Lett., 1969, 827 Miller, L.L. Greisinger, R. Boyer, R.F. J. Am. Chem. Soc., 1969, 91, 1578. 

A number of experiments have been carried out to determine the relative migratory aptitude of groups in pinacol/pinacolone type rearrangements, and in general the relative ease of migration is found to be ... 

This rearrangement can also be effected with catalytic amounts of either (CH3)3SiI or (CH3)3SiOTf in the case of a,(3-epoxy trimethylsilyl ethers. Yields are dependent on the migratory aptitude of the group that rearranges.2... 

Electrolysis of /J-hydroxy carboxylic acid (90) gave ketone (91) as the main product, which was converted to dl-muscone (Scheme 34) [113]. The migratory aptitude of alkyl substituents at the fi-position in the intermediate -hydroxy carbenium ion was scrutinized to show that vinyl, cyclopropyl, and benzyl groups rearrange predominantly. 

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