Amine oxides, allylic, rearrangements

The rearrangements of allylic sulfoxides, selenoxides, and amine oxides are an example of the first type. Allylic sulfonium ylides and ammonium ylides also undergo [2,3]-sigmatropic rearrangements. Rearrangements of carbanions of allylic ethers are the major example of the anionic type. These reactions are considered in the following sections. 

Rearrangement of Allylic Sulfoxides, Selenoxides, and Amine Oxides... 

A7-Ally] amine oxides represent the general pattern for [2,3]-sigmatropic rearrangement where X = N and Y = O The rearrangement provides O-allyl hydrox-ylamine derivatives. 

Scheme 2 shows Rapoport s synthesis [15]. The cinnamic acid derivative 3 prepared from m-methoxy benzaldehyde [20] was ethylated by diethyl sulfate to give ethyl cinnamate derivative 4, followed by Michael addition with ethyl cyanoacetate to afford compound 5. Compound 5 was converted to lactam 6 by the reduction of the cyano group and subsequent cyclization. Selective reduction of the lactam moiety of 6 was achieved by treatment with trimethy-loxonium fluorob orate followed by sodium borohydride reduction. Amine 8 was obtained by the reductive methylation of amine 7. Amine 8 was converted to compound 9 by methylene lactam rearrangement [21], followed by selenium dioxide oxidation to provide compound 10. Allylic rearrangement of compound 10 and subsequent hydrolysis gave compound 12. The construction of the decahydroisoquinoline structure began with compound 12,... 

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. 

Exposure of 2-methyl-2-imidazoline to a mixture of nitric and acetic acids leads to both oxidation and nitration, giving l,3-dinitroimidazolidin-2-one (179). When 2-nitramino-2-imidazolines are further nitrated they give the 1-nitro products (176) which are dinitroguanidines. Addition of amines and alcohols leads to (177) and (178), respectively, while allylic rearrangement followed by further nitration gives (179 Scheme 86). 

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). ... 

Amine oxides, sulfoxides, and selenoxides all undergo the [2,3] sigmatropic rearrangement. The equilibrium between allyl sulfoxides and allyl sulfenates lies on the side of the sulfoxide, but the equilibrium can be pushed toward the sulfe-nate by reduction of its O-S bond. 

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

Rearrangement of selenilimines obtained by the oxidation of allylic selenides affords a route to allylic secondary amines.[31] Amines obtained by allylic rearrangement were prepared by treating a variety of aliphatic or aromatic primary amines with an allylic selenide activated by N-chlorosuccinimide (Scheme 28). 

Allylic alcohols, 1, 17, 28-29, 30-31, 85-86, 182, 261, 318, 335, 338, 425, 444, 588, 602-603, 604, 664 AUyUc amines, 604-605 Allyhc chlorides, 598, 645 Aiiylic dibromides, 418 AUylic ethers, 269 Allylic halides, 327, 329 Allyhc hydroperoxides, 287 Allylic phosphine oxides, 340 Allylic rearrangement, 11-12 Allylic trifluoroacetoxylation, 360-361 Allylidenetriphenylphosphorane, 14-15 a-Allylpalladium chloride complexes, 45-47... 

Condensation of the sodium enolate of acetylacetone 194 with carbethoxy-cyclopropyltriphenyl tetrafluoborate 195 led in high yield to acetylcyclopen-tenyl ester 196 and thence to ketal aldehyde 197. The latter with m-methoxy-phenethyl magnesium chloride 198 yielded allylic alcohol 199, which on Claisen rearrangement with dimethylacetamide dimethylacetal afforded amide 200. Conversion to amine, amine oxide, and Cope elimination then led to the desired... 

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 ... 

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