36398-96-6Relevant academic research and scientific papers
Making a Vinyl-Trimethylenemethane Precursor through the Addition of Diethyl Azodicarboxylate to Tropone
Bushby, Richard,Jarecki, Christine
, p. 2335 - 2343 (2007/10/02)
Diethyl 2-oxo-6,7-diazabicyclonona-3,8-diene-6,7-dicarboxylate (11) has been prepared by the addition of diethyl azodicarboxylate to tropone.The 3,4-double bond was protected by reaction with triethyl orthoformate-ethanol-tosic acid (toluene-p-sulphonic acid), the 8,9-double bond reduced, and the enone unit deprotected with water-dioxane-tosic acid.The resultant enone was converted into the conjugated diene by reaction with methyl-lithium and dehydration.Hydrolysis ot the carbamate groups (KOH-MeOH) and oxidation (HgO) gave 2-methylene-6,7-diazabicyclonona-3,6-diene (9).UV irradiation of a glassy solution of this diaz ene at 77 K gave the first observable triplet ESR spectrum of a vinyl-trimethylenemethane biradical, 2-methylenecyclohept-3-ene-1,5-diyl (10).Despite the fact that this non-Kekule polyene has a triplet ground state, the singlet biradical reacts as such to give a mixture of 7-methylenebicyclohept-2-ene (28), 2-methylenebicyclohept-3-ene (29), and 3-methylenehepta-1,4,6-triene (30) faster than it undergoes intersystem crossing.Several interesting contrasts exist between the chemistry of the bridged vinyl-TMM precursor (9) and the equivalent bridged TMM precursor, 7-isopropylidene-2,3-diazabicyclohept-2-ene (4).In the former case, pyrolysis proceeds via the singlet biradical to give mainly monomeric products.There is no CIDNP effect and trapping with alkenes gives low yields of cycloadducts (Scheme 1).In the latter case, pyrolysis gives dimeric products via the triplet biradical.There is a strong CIDNP effect and in the presence of alkenes high yields of cycloadducts are obtained (Scheme 2).
SYNTHESIS AND THERMAL TRANSFORMATIONS OF BICYCLOALKENES CONTAINING A METHYLENECYCLOPROPANE FRAGMENT
Mil'vitskaya, E. M.,Pekhk, T. I.,Pereslegina, N. S.,Tarakanova, A. V.,Ivanov, A. V.
, p. 1573 - 1583 (2007/10/02)
The previously undescribed 8-methylenebicyclooct-2-ene (II) and 9-methylenebicyclonon-4-ene (IV) were synthesized by the dehydrohalogenation of 8-methyl-8-chlorobicyclooct-2-ene and 9-methyl-9-chlorobicyclonon-4-ene.It was established that the hydrocarbon (II) is thermally labile, whereas the hydrocarbon (IV) does not change right up to 300 deg C.The thermal transformations of the hydrocarbon (II) and its isomeric bicyclonona-1,6-diene (III) at 100 - 180 deg C were investigated.At 100 deg C a pseudoequilibrium is established between these hydrocarbons.The final and only products from the transformations of both hydrocarbons at 180 deg C are the previously unknown anti-Bredt hydrocarbon bicyclonona-2,7-diene (XXVIIIb) and 3-methylene-1,4-cyclooctadiene (XXV), formed in a ratio of 1 : 2.5.
Carbene Rearrangements, XI. Bicyclooct-2-en-7-ylidene
Brinker, Udo H.,Koenig, Lothar
, p. 894 - 910 (2007/10/02)
Three reactions are operative in bicyclooct-2-en-7-ylidene (6) generated by flash pyrolysis of the dry sodium salt of the corresponding tosylhydrazone.Cyclobutylidene-methylenecyclopropane rearrangement leads to bicycloocta-1,3-diene (18).A
TRANSFORMATIONS OF HYDROCARBONS OF BICYCLOHEPTANE SERIES WHEN TREATED WITH POTASSIUM tert-BUTOXIDE AND DIMSYL IN DIMETHYL SULFOXIDE
Mil'vitskaya, E. M.,Babushkina, O. Ya.,Ranneva, Yu. I.,Shapiro, I. O.,Luzikov, Yu. N.,et al.
, p. 1243 - 1246 (2007/10/02)
Bicycloheptane when treated with potassium tert-butoxide and dimsyl in DMSO remains unchanged.Its unsaturated derivatives in these solutions isomerize either with opening of the small ring or with a shift of the double bond in the six-membered ring.In the case of 7-methylenebicyclo-2-heptene an unusual rearrangement was observed, with the formation of tricyclo4,6>-2-octene.
