Nitrogen migration from

An alkyl group can also migrate from oxygen to nitrogen or phosphorus [I, 72] (Michaelis-Arbuzov rearrangement) With this methodology, tetrafluoro-pyndine phosphonates and phosphmates can be obtained [75, 74], Chlorine fluoride... 

Migration from nitrogen to carbon is observed also in aza-Cope rearrangement [76] Ring expansion occurs in thermal rearrangement of azindine denvauves [77] (equation 17)... 

The most famous of the rearrangements in which R migrates from carbon to nitrogen is undoubtedly the conversion of ketoximes to... 

These rearrangement processes are characterised by a transition state in which the alkoxyl group migrates from the amide nitrogen to the carbonyl carbon (Fig. 17a) and therefore involves HEteroatom Rearrangements On Nitrogen the HERON... 

Electron-rich alkenes like an enol ether react with N-allenylsulfonamides to assist a 1,3-shift of the sulfonyl group, eventually furnishing formal [4+2]-cycloaddition products, tetrahydropyridine derivatives. The sulfonyl group migrates from the nitrogen to the central allenyl carbon atom [25b, 195]... 

Because wholesale bans of this type will not occur, then another approach to achieving safety, at least for pollutants, might be suggested. Why not seek the goal of no detectable chemicals in the media of human exposure If automobiles emit various nitrogen oxides, simply ensure that emission rates are sufficiently low so that these noxious chemicals cannot be found in air. If PCBs are migrating from a hazardous waste site, impose limits on that migration so that no detectable PCBs are found in the off-site environment. Control afla-toxin contamination of raw food commodities to ensure none can be found in finished foods. Why not apply this approach to all pollutants (it obviously is not applicable to products) ... 

In contrast to 1,2-migrations between C and O, there are few reports on the Brook isomerization of a-silylamine (aza-Brook isomerization). The reaction of (a-silylallyl)amine 61 with n-C4H9Li in THF at low temperatnre followed by the addition of HMPA and CH3I gives the methylated prodnct 62 in qnantitative yield. These resnlts indicate that an aza-Brook isomerization occnrs, i.e. the silyl group of 61 migrates from carbon to nitrogen and the lithinm salt of an aUyl anion 63 is produced (equation 22) . 

The first step of the reaction is a rearrangement, with the halogen migrating from the nitrogen to the 4 or 5 position of the alkyl group and the second step, the ring closure takesplace. 

Other pubKcations dealing with the catalytic ability of electrogenerated cobalt(I) species have appeared. Cob(I)alamin reacts with 1,4-dibromobutane to yield a tet-ramethylene-1,4-di-Co -cobalamin complex [138]. Alkyl radicals (which arise from the oxidative addition of cobalt(I) tetraphenyl porphyrin to an alkyl halide) have been found to migrate from the cobalt center to a nitrogen of a pyrrole ring [139]. 

Examples exist of rearrangements in which a halogen atom migrates from annular nitrogen to carbon, or from one ring carbon to another ( halogen-dance or transmetalation). Such processes occasionally have preparative importance, and they will be covered in the appropriate sections. 

Light-catalyzed isomerization of azoxy derivatives to o-hydroxyazo-derivatives by exposure to sunlight, whereby the oxygen migrates from the nitrogen atom to which it is attached to the nucleus which is attached to the other nitrogen atom, seems to proceed via an intramolecular mechanism LXXVII I LXXX.12... 

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