264-08-4Relevant academic research and scientific papers
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.
THE OXIDATION OF BENZOTROPYLIUM CATION
Pomerantz, Martin,Swei, Gwo-Shin
, p. 3027 - 3030 (1982)
Oxidation of benzotropylium (1) fluoborate with Na2O2 and KO2 gives the benzotropones, 5 and 6, as the major products with no naphtalene (9) or other ring contracted products formed.Oxidation with m-chloroperoxybenzoic acid produces a small amount of naphtaldehydes (10 and 11) and even less naphtalene, along with the benzotropones, while oxidation with H2O2 and t-butyl peroxyacetate gives slightly more of the ring contracted naphtaldehydes than benzotropones, in addition to a small quantity of naphtalene.All reactions produce some 1,2-benzotropolidine (8).
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.
Thermal Reorganizations of 1,2:3,4-Dibenzotropilidene (5H-Dibenzocycloheptene), 7,7'-Bi(1,2:3,4-dibenzotropyl) cycloheptenyl)>, and the 1,2:3,4-Dibenzotropyl (Dibenzocycloheptenyl) Free Radical
Pomerantz, Martin,Dassanayake, Nissanke L.,McManus, Timothy R.,Reynolds, Charles H.
, p. 4029 - 4032 (2007/10/02)
1,2:3,4-Dibenzotropilidene (5H-dibenzocycloheptene, 8) has been shown to thermally produce phenanthrene (12), 9-methylphenanthrene (13), 9,10-dihydrophenanthrene (14), and 1,2:3,4-dibenzocycloheptadiene (6,7-dihydro-5H-dibenzocycloheptene, 15).With added naphthalene, to trap the extruded one-carbon species, 1,2-benzotropilidene (16), α-methyl- and β-methylnaphthalene (17 and 18), 1,2-benzo-1,3-cycloheptadiene (19), and benzocycloheptene (20) were also produced.Reaction of 1,2-benzotropilidene with phenanthrene produced 1,2:3,4-dibenzotropilidene (8) and naphthalene, showing the reversibility of this thermal carbon extrusion reaction. 7,7'-Bi(1,2:3,4-dibenzotropyl) cycloheptenyl), 10> was prepared by VCl2 reduction of the 1,2:3,4-dibenzotropylium cation.Thermally it underwent the same reactions as 8, demonstrating that it is the 1,2:3,4-dibenzotropyl (dibenzocycloheptenyl) free radical (9) which lost a carbon atom (CH group) to the aromatic acceptor.At 200 deg C the dimer 10 produced significant quantities of 9-methylphenanthrene (13), shown not to arise from 8, in addition to phenanthrene, 12.Mechanisms for the thermal transfer of a CH group from 9 to an aromatic acceptor and for the production of 13 from 9 are presented.
PHOTOCHEMISTRY OF BENZOTRICYCLO2,7>HEPTENE: SINGLET EXCITED STATE REACTIONS DERIVED FROM CYCLOPROPANE RING CLEAVAGE
Johnson, Richard P.,Davis, Katherine Schlimgen
, p. 3171 - 3174 (2007/10/02)
Direct irradiation of the title hydrocarbon in cyclohexane affords 2-vinylindene and benzonorcaradiene as major primary photoproducts.Deuterium labeling is used to determine reaction mechanisms.
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.
Conversion of Benzo- and Naphthonorcaradien-7-yl to Benzo- and Naphthotropyl Radicals
Pomerantz, Martin,Dassanayake, N. L.
, p. 678 - 682 (2007/10/02)
Thermal decompositions of tert-butyl 2,3-benzonorcaradiene-7-percarboxylate (7), tert-butyl 2,3-(2',3'-naphtho)norcaradiene-7-percarboxylate (8), bis(2,3-benzonorcaradiene-7-carbonyl) peroxide (9), and bis peroxide (10) have been studied with particular attention paid to the hydrocarbon products, 2,3-benzonorcaradiene (11) and 1,2-benzotropilidene (12) from 7 and 9, and 2,3-(2',3'-naphtho)norcaradiene (14) and 1,2-(2',3'-naphtho)tropilidene (15) from 8 and 10.The variation of product ratio with solvent from 7 and 8 suggests that the intermediate benzo- and naphthonorcaradien-7-yl radicals competitively abstract a hydrogen atom or undergo ring opening to the corresponding tropyl radical.A similar study of 9 and 10 suggests that there is an additional, polar component to formation of seven-membered ring products 12 and 15.Since the hydrocarbon products are free radical in origin, it is suggested that the intermediates, whether highly polarized species or free cations, must revert back to free radicals before giving these products.It is further suggested that the greater degree of ring opening from the diacyl peroxides, 9 and 10, is due to the greater allowedness of the ring opening of the norcaradienyl type cations relative to the corresponding radicals.It is also demonstrated that benzonorcaradienyl intermediates undergo ring opening more readily than the corresponding naphthonorcaradienyl intermediates.
Thermal Extrusion of a One-Carbon Species from 1,2-Benzotropilidene (5H-benzocycloheptene), the Benzotropyl (Benzocycloheptenyl) Free Radical, 1,2:5,6-Dibenzotropilidene (5H-Dibenzocycloheptene), and the 1,2:4,5-Dibenzotropyl (Dibenzocycloheptenyl) Free Radical
Pomerantz, Martin,Combs, Gerald L.,Fink, Rina
, p. 143 - 149 (2007/10/02)
The benzotropyl dimer 7,7'-bis(3,4-benzotropyl) (6) has been prepared and thermolyzed (400 deg C) both without and with added benzene.In addition, 1,2:5,6-dibenzotropilidene (3) and 7,7'-bis(1,2:5,6-dibenzotropyl) (7) have been pyrolyzed (430 deg C) both without and with added naphthalene.The similarity of the products obtained in the former pyrolysis, namely, naphthalene (12), α-methylnaphthalene (13), β-methylnaphthalene (14), 1,2-benzocyclohepta-1,3-diene (15), benzocycloheptene (16) and toluene (whwn benzene is used), with those obtained from pyrolysis of 1,2-benzotropilidene (1) confirms that both thermolyses involve the benzotropyl radical.The similarity of the products from the latter two pyrolyses (of 3 and 7), namely, anthracene (4), 9-methylanthracene (5), 9,10-dihydroanthracene (17), 1,2:4,5-dibenzo-1,4-cycloheptadiene (20), 1- and 2-methylanthracene (18 and 19), and, when naphthalene (12) was used, benzotropilidene (1) and 1- and 2-methylnaphthalene (13 and 14), shows that both of these go through a common intermediate, the 1,2:4,5-dibenzotropyl radical (8). 9-Methylanthracene (5) was shown to thermally produce anthracene (4) and 1- and 2-methylanthracene (18 and 19), but, even with this complication, anthracene (4) was shown to be a primary product from the pyrolysis of dibenzotropilidene (3).Attempts to use di-tert-butyl nitroxide (21) as an initiator (400 deg C) gave primarily Diels-Alder addition of the isobutylene formed by decomposition of the nitroxide with both 1,2:4,5-dibenzotropilidene (the product of a 1,5-hydrogen shift in 3) and 9-methylanthracene (5).A lower temperature (345 deg C) reaction of 3 with naphthalene in the presence of nitroxide 21 did produce anthracene (4) and benzotropilidene (1) in addition to the Diels-Alder adduct, confirming the free-radical nature of the reaction.Low-temperature control experiments employing the benzotropyl dimer (6) (280 deg C) and the dibenzotropyl dimer (7) (345 deg C) showed that they were undergoing cleavage to their respective radicals (2 and 8) and that these were giving product directly, rather than the benzo- and dibenzotropilidenes (1 and 3), which were being formed in the reactions by hydrogen abstraction, giving the products.It has thus been demonstrated that the benzo- and dibenzotropyl radicals (2 and 8) can transfer a CH group to an aromatic acceptor and that the pyrolytic reactions of benzo- and dibenzotropilidenes (1 and 3) to give naphthalene and anthracene are CH-transfer reactions of the tropyl radicals formed by hydrogen abstraction.Yields of up to 65percent of anthracene (4) have been realized in the pyrolyses of dibenzotropilidene (3).Mechanisms for these CH-transfer reactions are presented.A contrast is made between the low-temperature reaction of the dibenzotropyl dimer (7) which (345 deg C) gives only anthracene and dibenzotropilidene (3), by CH loss and hydrogen abstraction, respectively, and the low-temperature (280 deg C) reaction of benzotropyl dimer (6) which not only gives naphthalene (12) and benzotropilidene (1) by CH loss and hydrogen ...
