Rearrangement with simultaneous

In a related rearrangement with simultaneous oxidation by palladium on carbon in toluene at 1103C, dihydroazepines 13 were formed in 80-100% yield.82... 

Reaction type 6B of Table 10-1 is allylic rearrangement with simultaneous condensation with another molecule. The reaction, which is catalyzed by prenyl-transferases,3073 occurs during the polymerization of polyprenyl compounds (Fig. 22-1,Eqs. 22-2,22-3). Experimental evidence favors a carbocation mechanism for all of these reactions.308 309 See Chapter 22. 

Various unsaturated cyclic 7t-ligands undergo, within a transition-metal complex, cycloaddition reactions and rearrangements with simultaneous formation of cyclopropane subunits. This is observed with cycloheptatriene ehromium and iron complexes such as 4 which give cycloaddition products, e.g. 

Other methods for the preparation of cyclohexanecarboxaldehyde include the catalytic hydrogenation of 3-cyclohexene-1-carboxaldehyde, available from the Diels-Alder reaction of butadiene and acrolein, the reduction of cyclohexanecarbonyl chloride by lithium tri-tcrt-butoxy-aluminum hydride,the reduction of iV,A -dimethylcyclohexane-carboxamide with lithium diethoxyaluminum hydride, and the oxidation of the methane-sulfonate of cyclohexylmethanol with dimethyl sulfoxide. The hydrolysis, with simultaneous decarboxylation and rearrangement, of glycidic esters derived from cyclohexanone gives cyclohexanecarboxaldehyde. 

The Curtius rearrangement, like the Hofmann rearrangement, involve migration of an -R group from the G-O carbon atom to the neighboring nitro gen with simultaneous loss of a leaving group. The reaction takes place on heat ing an acyl azide that is itself prepared by nucleophilic acyl substitution of m acid chloride. 

The 2,4-ct.v relation of the hydroxy and the ester function in both isomers is explained by a cyclization reaction with simultaneous formation of a dioxycarbocation, presumably via a preceding 2-azonia-Cope rearrangement. Treatment with water then provides the observed... 

Thus the average lifetime of the neophyll radical depends on the probability of encountering an aldehyde molecule and hence on the aldehyde concentration. At high aldehyde concentrations the radical is removed by reaction (3) before it has an opportunity to rearrange. This would not be the case if rearrangement were simultaneous with formation of the radical. 

This stereochemical outcome of the Fritsch-Buttenberg-Wiechell rearrangement is well compatible with the crystal structure of the carbenoid 3 (Figure 1, Scheme 4). The aryl moiety trans to the vinylic chlorine atom is bent towards Cl (C1-C2-C9 116.5°). Thus, migration of the fraw -aryl group with simultaneous liberation of lithium chloride becomes evident. The free vinylidene carbene can be ruled out as the intermediate. 

Rearrangement of 273 with simultaneous loss of triphenylphosphine oxide 274 produces the intermediate nitrilium ion 225 that affords the corresponding amide 218. Aldoximes are easily converted to their corresponding nitriles 219 under the same reaction conditions. 

Gronowitz and Moses suggest that cyclization with simultaneous rearrangement may occur in compounds containing the thioglycolic acid... 

Substitution of the appropriate constants, along with simultaneous combination of these results with those of Equation 3, yield (upon rearrangement)... 

Phenols have been prepared on solid phase by aromatic nucleophilic substitution with hydroxide, by thermal rearrangement of vinylcyclobutenones, by oxidative coupling of phenols (Figure 5.20 [65]), by cyclocondensation reactions with simultaneous release of the phenols into solution (Entry 12, Table 7.6), and by Claisen rearrangement [66]. 

Complex products were also obtained from electron-poor dienes50. Photolysis of (t-Bu2Si)3 with tetrazine 8 gave a complex mixture of products, from which 9 and 10 could be isolated (equation 20). In 10, one of the CF3 groups has been completely degraded, with simultaneous rearrangement of the ring skeleton. The reaction with oxadiazole 11 also took an unexpected course (equation 21). 

It was found possible to measure the kinetics of cleavage of protonated sec-butyl methyl ether 24 by following the disappearance of the methoxy doublet in the NMR spectrum with simultaneous formation of protonated methanol and ferf-butyl cation. The cleavage shows pseudo-first-order kinetics. Presumably, the rate-determining step is the formation of sec-butyl cation followed by rapid rearrangement to the more stable ferf-butyl cation... 

Oxidation of organic substrates. This hydroperoxide converts 2,3-dimethyl-2-butcne into tetramethylethylene oxide with simultaneous formation of 3-bromo-4,5-dihydro-5-hydroxy-4,4-dimethyl-3,5-diphenyl-3H-pyrazole (2). Dialkyl olefins, however, are not epoxidized by I. Enol ethers are converted to a variety of epoxide rearrangement products.2... 

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