264-08-4Relevant articles and documents
THE PHOTOCHEMISTRY OF BENZOTRICYCLO2,6>HEX-3-ENE
Kouwenhoven, Arjan P.,Noort, Paul C. M. van,Cerfontain, Hans
, p. 1745 - 1748 (1981)
Irradiation of 1 in methanol with λ 254 nm yields 3 and 4 as the main primary products which result from the excited singlet state by initial cyclopropane bond homolysis, but no primary photosolvolysis products.
Base-promoted Eliminations within Halogenated Propellene Frameworks
Banwell, Martin G.,Halton, Brian,Hambley, Trevor W.,Ireland, Neil K.,Papamihail, Con,et al.
, p. 715 - 724 (2007/10/02)
The reactions of halogenated propellenes with potassium t-butoxide have been investigated.Propelladiene 9,9-dichloro-1,4,5,8-tetrahydro-4a,8a-methanonaphthalene affords 1,6-methanoannulene, 4-methylazulene, and 5H-benzocycloheptene, while the related tetracyclic compound 1,1,8,8-tetrachloro-1a,2,3,6,7,7a-hexahydro-2a,6a-methano-1H-cyclopropanaphthalene reacts to give 12-chlorotricyclo3,5>dodeca-1,3(5),6,8,10-pentaene.Treatment of 8,8-dichloro-2,3,4,7-tetrahydro-3a,7a-methano-1H-indene with the same base produced a mixture of the chlorodiene 8-chloro-2,3-dihydro-3a,7a-methano-1H-indene, azulene, and 4-methylazulene.The structure of the chlorodiene was established by an X-ray crystallographic study of its Diels-Alder adduct with 4-phenyl-4H-1,2,4-triazole-3,5-dione.While reaction of tetracycle 1,1,syn-8-trichloro-1a,2,3,6,7,7a-hexahydro-2a,6a-methano-1H-cyclopropanaphthalene with base failed to produce any characterisable products, under the same conditions epimer 1,1,anti-8-trichloro-1a,2,3,6,7,7a-hexahydro-2a,6a-methano-1H-cyclopropanaphthalene was converted into the cycloproparene tricyclo3,5>dodeca-1,3(5),6,8,10-pentaene.Mechanistic proposals which account for the observed conversions have been advanced and are supported by 13C-labelling studies.The initial steps in most of the reaction pathways of the substrates are probably 1,4-elimination processes involving abstraction of an allylic hydrogen, fragmentation of the strained propellene ?-bond, and ejection of the halogen in an endo-relationship to the abstracted proton.The primary product of these processes, bridgehead dienes such as bicycloundeca-1,3,6(11),8-tetraene, 4,4,12-trichlorotricyclo3,5>dodeca-1(11), 7(12),9-triene and 10-chlorobicyclodeca-1,3,6(10)-triene, then undergo further reaction involving, amongst other things, 1,3-prototropic shifts.Attempts to probe the mode of formation of the C11-4-methylazulene from the C10-precursor 8,8-dichloro-2,3,4,7-tetrahydro-3a,7a-methano-1H-indene have uncovered a novel methylation reaction of azulene by the dimsyl anion.
Thermolysis of Thiophenedicarboxylic Acid Anhydrides as a Route to Five-Membered Hetarynes
Reinecke, Manfred G.,Newsom, James G.,Chen, Lao-Jer
, p. 2760 - 2769 (2007/10/02)
Flow vacuum thermolysis (FVT) of the anhydrides of thiophene-2,3- (5) and -3,4-dicarboxylic acid (6) and of thianaphthene-2,3-dicarboxylic acid (7) in the presence of thiophene, 1,3-cyclohexadiene, or benzene gave thianthrene (15a), presumably by aromatization of an intermadiate Diels-Alder adduct of the diene traps and the aryne 2,3-didehydrothiophene (8).A similar rationale explains the formation of dibenzothiophene from 7 and thiophene, the four monomethylthianaphthenes 22-25 from 5 and cyclopentadiene, 5,6-dimethylthianaphthene (15f) from 5 and 2,3-dimethylbutadiene, and a mixture of hydroxythianaphthenes (15d) from 5 and furan.The latter reaction also produces a mixture of isomeric cyclopentanothiophenes (19) which probably arise by decarbonylation of 15d.An FVT reaction of 5 with propyne as the trap gave a mixture of allenyl-(28) and propynylthiophenes 29 which probably arise by an ene reaction of the trap and the aryne 8.Decomposition of the anhydrides 5 and 6 in molten anthracene led only to Friedel-Crafts products such as thienylanthracenes 33 and quinones 34 from 5 and 39 and 40 from 6.The diene reactivity of thiophene 13a in the gas phase was demonstrated by the formation of naphthalene from its reaction with benzyne generated from the thermolysis of indanetrione and by the formation of indene from 13a plus cyclopentadiene.Possible, but improbable, interpretations of the FVT results without invoking a five-membered hetaryne intermediate are considered.
