Vinyl Migration Research Articles

The Behavior of Thiochromanone and Isothiochromanone Sulfoxides in the Schmidt Reaction: Isolation of a Novel Azide Product from Thiochromone Sulfone

The Schmidt reaction has been carried out on thiochroman-4-one 1-oxide and a number of related sulfoxides. In all cases lactam formation by attack of HN3 on the carbonyl group of the keto sulfoxide appears to predominate, with no evidence for sulfoximine formation. The question of aryl vs. alkyl migration, as in other systems, is dependent on the degree of substitution of the alkyl group. When the Schmidt reaction was carried out upon thiochromone 1,1-dioxide two products, the lactam resulting from preferential vinyl migration and a novel α-azido sulfone resulting from 1,4-addition, were obtained.

Aryl versus alkyl and vinyl migration in the mass spectra of sulphone derivatives

AbstractThe 2‐acetoxyethyl aryl sulphones were found to be unsuitable for a comparative study with the corresponding chlorides and alcohols as their predominant fragmentation involved cleavage of the aliphatic carbon‐sulphur bond with charge retention on the aliphatic part of the molecule The expected McLafferty rearrangement to yield an intermediate vinyl species was only a minor fragmentation path.Indirect evidence for alkyl migration in the molecular ion was found in the spectrum of 2‐acetoxyethyl 1‐paranitro phenyl sulphone. The spectra of the aryl vinyl sulphones revealed intense [Aryl SO]+ ions resulting from preferred migration of the vinyl group from sulphur to oxygen.

Alumina: Catalyst and support: XXX. Dehydrogenation and skeletal isomerization of butylbenzenes over chromia-alumina catalysts

The dehydrogenation of butylbenzenes at about 490 ° was investigated over “nonacidic” chromia-alumina B and over “acidic” chromia-alumina A catalyst. Both catalysts produced the “normal” dehydrogenation products and also their skeletal isomers. The skeletally isomerized butenylbenzenes over chromia-alumina B were n-butenylbenzenes from sec-butylbenzene, sec-butenylbenzenes from n-butylbenzene and isobutenylbenzenes from tert-butylbenzene. The rearrangement can best be explained by a radical mechanism involving phenyl and/or vinyl migration. In the presence of the acidic chromia-alumina A catalyst, the product of rearrangement consisted also of isobutenylbenzenes from either sec- or n-butylbenzene and of sec-butenylbenzenes from isobutylbenzene. In the presence of the acidic catalyst tert-butylbenzene produced substantial amounts of benzene and isobutylene, while chromia-alumina B did not form products of dealkylation. The difference in the results between the two catalysts can be ascribed to the cationic reactions occurring on chromia-alumina A. Small amounts of methylindans and naphthalene and tetrahydronaphthalene were also produced.