Meisenheimer rearrangement amine oxides

Rearrangement, Aliphatic amine oxides without an ahphatic hydrogen atom P to the nitrogen undergo Meisenheimer s rearrangement when heated to give trisubstituted hydroxylamines. 

Isoprene (2-methyl-1,3-butadiene) can be telomerized in diethylamine with / -butyUithium as the catalyst to a mixture of A/,N-diethylneryl- and geranylamines. Oxidation of the amines with hydrogen peroxide gives the amine oxides, which, by the Meisenheimer rearrangement and subsequent pyrolysis, produce linalool in an overall yield of about 70% (127—129). 

The use of m-CPBA allows the formation of nitrones in the oxidation of tertiary amines. The resulting amines A-oxides are subject to either Cope or Meisenheimer rearrangements, providing formation of nitrones. Thus, the generated corresponding nitrones in the oxidation of bicyclic aziridines give nitrones as a result of a Meisenheimer rearrangement (Scheme 2.14) (93). 

Oxidation of organonitrogen compounds is an important process from both industrial and synthetic viewpoints . N-oxides are obtained by oxidation of tertiary amines (equation 52), which in some cases may undergo further reactions like Cope elimination and Meisenheimer rearrangement . The oxygenation products of secondary amines are generally hydroxylamines, nitroxides and nitrones (equation 53), while oxidation of primary amines usually afforded oxime, nitro, nitroso derivatives and azo and azoxy compounds through coupling, as shown in Scheme 17. Product composition depends on the oxidant, catalyst and reaction conditions employed. 

The Meisenheimer rearrangement of tertiary amine N- oxides has been applied to the synthesis of both monocyclic 1,2-oxazepines, e.g. (309) (65JOC3135, 65JCS1653, 82H(19)173), and those fused to benzene (80AJC833) and a variety of heterocyclic rings (80AJC1335). 

Sigmatropic Rearrangements of Tertiary Amine Oxides (The Meisenheimer Rearrangement)... 

The thermal rearrangement of tertiary amine oxides, the Meisenheimer rearrangement, generates O, A,A-trisubstituted hydroxylamines. 

The application of the Meisenheimer rearrangement in stereoselective synthesis is restricted because of the difficulty in obtaining enantiomerically pure allyl amine oxides and because of the long reaction time. 

Chiral tertiary allylic amines 191 with /ra r-2-phenylsulfonyl-3-phenyloxaziridine 33 also gave rise to amine A -oxides 192, which underwent the [2,3]-Meisenheimer rearrangement to hydroxylamines 193 with a high level of stereoselectivity (Table 14) <1999J(P1)2327>. Reduction of 193 gave the corresponding allylic alcohols 194. 

The following reaction mechanism was ruled out by the authors cited [4 + 2] cycloaddition of the diene with the nitrone to give tertiary amine oxide, 7-21, which then thermally rearranges to the product. (Thermal rearrangement of a tertiary amine oxide to an alkylated hydroxylamine is called a Meisenheimer rearrangement.)... 

There are not many examples of the direct transformation of an allylic amino to a rearranged oxygen functionality. One example is found in the Meisenheimer rearrangement of amine oxides, which occurs with almost complete chirality transfer, as seen in equation (23). ... 

Johnstone, R. A. W. Meisenheimer rearrangement of tertiary amine oxides. Mechanisms of Molecular Migrations 1969, 2, 249-266. 

Meisenheimer rearrangement The rearrangement of a tertiary amine oxide on heating to give a substituted hydroxylamine. The migrating group is usually allylic or benzylic. 

Meisenheimer rearrangement. Allylic amines are oxidized to give A-oxides at low temperatures. On warming up 0-allylhydroxylamines are generated, which can be cleaved by Zn-HOAc. ... 

Meisenheimer rearrangement. Rearrangement of tertiary amine oxide to 0,lV,lV-trisubstituted hydroxylamines. 

This view was based on a kinetic analysis of the Meisenheimer rearrangement of the related amine oxide where a radical dissociation-recombination mechanism was proposed 131>. 

MEISENHEIMER N-Oxide Rearrangement Rearrangement of tertiary amine oxides to trisubstituted hydroxylamines via a [2,3] sigmatropic shift. Also chlorination of pyridines via N-oxides (see 1st edition). 

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