R group migration

Monohydroboration of terminal alkynes with relatively unhindered dialkylborane is accompanied by competing dihydroboration, while for thexylmonoalkylboranes both thexyl and R group migrates competitively. 

The sixth axial coordination of a base (L) also affects the rate of metal-carbon bond cleavage via an intramolecular electron transfer from the mbonded axial ligand (R) to the metal center in [(TPP)Co(R)(L)]+ produced by the one-electron oxidation of (TPP)Co(R), which leads to R group migration from the metal to ni-... 

The reaction between trialkylboranes and iodine to give alkyl iodides was mentioned at 12-31. When the substrate contains a vinylic group, the reaction takes a different course," " " with one of the R groups migrating to the carbon, to give alkenes." " The reaction is stereospecific in two senses (7) if the groups... 

The R— group migrates to the the nitrogen to give a bromo nitrogen as a bromide ion departs. 

Studies of the Hofmann rearrangement of optically active amides in which the chirality center is directly attached to the carbonyl group have shown that these reactions occur with retention of configuration. Thus, the R group migrates to nitrogen with its electrons, but without inversion. 

The group transfer reactions can be easily explained by perturbation molecular orbital (PMO) approach. If both the R groups migrate without inversion, in a... 

FIGURE 6 3 PMO oach fof S P transfer reaction when both the R groups migrate suprafacially. 

Formation of O, N, A -trisubstituted hydroxylamines from tertiary amine oxides via [1,2]-R group migration, or [2,3]-sigmatropic rearrangement when R = allyl ... 

Furthermore, stereogenic R groups migrate with retention of configuration. 

The catalysed synthesis of amides from oximes is usually associated with the Beckmann rearrangement, where an R group migrates to give the for-mamide. In an alternative methodology, the catalysed rearrangement of... 

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