Amine-catalyzed rearrangements

Transformation of enolizable a-haloketones to esters, carboxylic acids, or amides via alkoxide-, hydroxide-, or amine-catalyzed rearrangements, respectively. 

Regarding the amine-catalyzed rearrangement of the p-nitrophenylhydrazone [81JHC723 83JCS(P2)1203], all the amines catalyze the reaction nevertheless, depending on the nature of the amine, different catalysis laws are observed. Tertiary amines and secondary amines with great... 

One-pot phosphine-promoted domino reaaion of Morita-Baylis-Hfllman carbonates and p,Y-unsaturated a-keto esters led to 2,3-dihydrofurans which suffer secondary amine-catalyzed rearrangement to provide 2-methyl-2f/-pyrans (Scheme 2) (14EJ01189).The synthesis of bis-fused benzo-2E/-py-ran derivatives occurs through a molecular iodine mediated 6-endo-dig iodocyclization reaction of appropriate dipropargyloxyarenes (14S1807). 

Scheme 40.25 Mechanism of the tertiary amine-catalyzed rearrangement of O-allylic trichloroacetimidates to allylic amides.

Finally, an acid catalyzed rearrangement of an o-(2-arylphenyl)-hydroxyl-amine followed by a ring enlargement to yield some unsaturated 7-aryl-azepinones should be mentioned (not shown). Until now, scope and limitations of that process are not known [52]. 

The base-catalyzed rearrangement of oxadiazolylureas 184 into ben-zoylamino-l,2,4-triazolin-5-ones 185 has been mechanistically examined by using amines as catalysts in acetonitrile and benzene, and borate buffers at various pS in dioxan-water [90JCS(P2)1289]. For the piperidine-... 

Overman, L. E. Zipp, G. G. Allylic transposition of alcohol and amine functionality by thermal or Pd(II)-catalyzed rearrangements of allylic N-benzoylbenzimidates. J. Org. Chem. 1997, 62, 2288-2291. 

The palladium(II)-catalyzed rearrangement of allyl imidates for the formation of allyl amines has also been investigated for chiral imidates (Eq. (6)) [12], The chiral imidate 15 undergoes a palladium(II)-catalyzed rearrangement to 16, which was applied for the synthesis of (/ )-N-(trichloracetyl)norleucinol 17 as presented in Eq. (6). 

Photosensitized cyclobutanation. Conjugated dienes and enamides undergo photosensitized cross addition to provide cycloadducts, which can be hydrolyzed to vinyl cyclobutylamines. These secondary amines undergo a base-catalyzed rearrangement to give cyclohexenes corresponding to the Diels-Alder adducts of the diene and the enamide. 

Overman, L.E. and Zipp, G.G. 1997. AUyhc transposition of alcohol and amine functionality by thermal or palladium (ll)-catalyzed rearrangements of aUylic A-benzoylbenzimidates. Journal of Organic Chemistry, 62 2288-91. 

Aromatic and aliphatic primary amines can be oxidized to the corresponding nitro compounds by peroxy acids and by a number of other reagents. The peroxy acid oxidations probably go by way of intermediate hydroxylamines and nitroso compounds (Scheme 2). Various side reactions can therefore take place, the nature of which depends upon the structure of the starting amine and the reaction conditions. For example, aromatic amines can give azoxy compounds by reaction of nitroso compounds with hy-droxylamine intermediates aliphatic amines can give nitroso dimers or oximes formed by acid-catalyz rearrangement of the intermediate nitrosoalkanes (Scheme 3). 

This type of precursor has been widely used for the synthesis of different 8-substituted theophyllines.Thus, treatment of 5-(aryldiazenyl)-l,3-dimethyluracil-6-amines with ethyl propiolate gives the corresponding Michael-type adducts, 5-(aryldiazenyl)-l, 3-dimethyl-6-[(2-cthoxycarbonylvinyl)amiiio]uiacils, which on treatment with a mixture of hydrochloric and acetic acid result in acid-catalyzed rearrangement to give the 8-(anilinomethyl)theophylline derivatives, c.g. the sequence 8 9 10. 

Russell, G. A., Mikol, G. J. Acid-catalyzed rearrangements of sulfoxides and amine oxides. The Pummerer and Polonovski reactions. Mech. 

An alternative to the base-catalyzed rearrangement of oxaziridines to ketones, discussed in Section 1.12.3.2.1, is the acid-catalyzed hydrolysis of oxaziridines derived from amines and acetone <75AJC2547>. Oxidation of C,A-diarylaldimines (Ar CH=N-Ar2) with sodium perborate in... 

Cyclobutanol was obtained by deamination of (cyclopropylmethyl)amine in 40% yield. Cyclopropylmethanol was a major byproduct in this reaction. A more efficient synthesis of cyclobutanol is the acid-catalyzed rearrangement of cyclopropylmethanol with aqueous hydrochloric acid " cyclobutanol was obtained in 72% yield containing a trace of the allyl alcohol. This transformation forms the basis of an efficient cyclobutene synthesis. ... 

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