13407-18-6Relevant articles and documents
Organic Photochemistry with 6.7-eV Photons: The Photochemistry of Bicyclohept-2-ene (2-Norcarene)
Leigh, William J.,Srinivasan, R.
, p. 514 - 519 (1983)
The photochemistry of bicyclohept-2-ene (2-norcarene) upon direct and triplet-sensitized photolysis has been investigated.The results differ significantly from those of previous studies on related systems.Direct photolysis with monochromatic radiation in the region 185-230 nm leads to a variety of products, of which cis-1,3,6-heptadiene, the major product, is shown by deuterium labeling studies to result from formal electrocyclic ring opening in a manner analogous to the 1,3-cyclohexadiene/1,3,5-hexatriene interconversion.The evidence suggests that this process may occur via a concerted mechanism in the singlet state.The other products arise from activation of the two cyclopropane bonds that are in conjugation with the olefinic group.The product distribution is independent of both solvent and excitation wavelength and is unchanged by the addition of naphthalene.Toluene-sensitized photolysis results in the formation of cis-1,3,6-heptatriene and bicyclohept-2-ene, which can be rationalized as resulting from decay of a common biradical intermediate.
185-nm Photolysis and Pyrolysis of the Spirocyclopropane-Substituted Azoalkanes of 2,3-Diazatricyclo4,9>non-2-ene and Their Denitrogenated Hydrocarbon Products, the Tricyclo2,7>heptanes
Adam, Waldemar,Zang, Gerald
, p. 3315 - 3323 (1991)
The 185-nm photolysis and pyrolysis of the spirocyclopropane derivatives of the azoalkanes 2,3-diazatricyclo4,9>non-2-ene (1a), 4',5'-diazaspiro(cyclopropane-1,8'-tricyclo3,7>non-4'-ene) (1b), and 4',5'-diazadispiro(cyclopropane-1,2'-tricyclo3,7>non-4'-ene-8',1''-cyclopropane) (1c) and their denitrogenated hydrocarbon derivatives tricyclo2,7>heptane (2a), spiro(cyclopropane-1,3'-tricyclo2,7>heptane (2b), and dispiro(cyclopropane-1,3'-tricyclo2,7>heptane-6',1''-cyclopropane) (2c) were investigated.It was shownthat the 185-nm photochemical behavior of these substrates does not depend on the degree of spirocyclopropane substitution.As common products in the 185-nm photolysis of the azoalkanes 1a-c were obtained the tricycloalkanes 2a-c (major products), the norbornenes 3a-c, the vinylcyclopentenes 5a-c (minor products), and the exo-methylenecyclohexenes 6a-c (traces).In the case of the parent azoalkane 1a additionally bicyclohept-2-ene (4) and bicyclohept-2-ene (7a) were detected.The major products in the photolysis of the tricycloheptanes 2a-c were the vinylcyclopentenes 5a-c, but also the norbornenes 3a-c and the methylenecyclohexenes 6a-c were formed in considerable amounts.Although the norbornenes 3a-c and the bicycloheptene 4a are logical Wagner-Meerwein rearrangement products, attempts to trap the suspected radical-cationic and zwitterionic intermediates with CF3CH2OH failed.Efforts to generate the authentic radical-cationic species by means of photosensitized elctron transfer (PET) by using sensitizers such as cyanoarenes, quinones, and pyrylium salts were unproductive.Vibrationally excited bicyclohepta-2,7-diyls, generated by the pyrolyses of 2a-c, are not precursors to the norbornenes 3a-c because, instead of such rearrangement products, cyclobutane cleavage of the bicyclopentane moiety takes place to afford the isomeric vinylcyclopentenes 5'a-c.Carbene intermediates, produced either from the 1,3-diyl-type species through fragmentation or from the photodenitrogenation of diazoalkanes, which are generated by retro-cleavage of n,?* excited azoalkanes 1a-c, in turn obtained through internal conversion of higher excited states such as 1?,?*, 1n,?*, and Ry, are proposed as the most likely precursors to either the vinylcyclopentenes 5a-c or methylenecyclohexenes 6a-c, respectively.In violation of Kasha's rule, photochemistry directly from the higher states of the azoalkanes 1a-c competes with internal conversion to the lowest excited state, namely the n,?* state, as it was shown by the formation of norbornenes 3a-c.
THE TRANSITION METAL COMPLEX PROMOTED ISOMERIZATION OF trans-BICYCLOHEPT-3-ENE TO cis-BICYCLOHEPT-3-ENE
Gassman, Paul G.,Bonser, Steven M.
, p. 3431 - 3434 (1983)
An unprecedented isomerization of a trans-1,2-disubstituted cyclopropane to a cis-1,2-disubstituted cyclopropane has been achieved with both rhodium(I) and platinum(II) catalysts.
Flash vacuum pyrolysis over magnesium. Part 1 - Pyrolysis of benzylic, other aryl/alkyl and aliphatic halides
Aitken, R. Alan,Hodgson, Philip K.G.,Morrison, John J.,Oyewale, Adebayo O.
, p. 402 - 415 (2007/10/03)
Flash vacuum pyrolysis over a bed of freshly sublimed magnesium on glass wool results in efficient coupling of benzyl halides to give the corresponding bibenzyls. Where an ortho halogen substituent is present further dehalogenation gives some dihydroanthracene and anthracene. Efficient coupling is also observed for halomethylnaphthalenes and halodiphenylmethanes while chlorotriphenylmethane gives 4,4′-bis(diphenylmethyl)biphenyl. By using α,α′-dihalo-o-xylenes, benzocyclobutenes are obtained in good yield, while the isomeric α,α′-dihalo-p-xylenes give a range of high thermal stability polymers by polymerisation of the initially formed p-xylylenes. Other haloalkylbenzenes undergo largely dehydrohalogenation where this is possible, in some cases resulting in cyclisation. Deoxygenation is also observed with haloalkyl phenyl ketones to give phenylalkynes as well as other products. With simple alkyl halides there is efficient elimination of HCl or HBr to give alkenes. For aliphatic dihalides this also occurs to give dienes but there is also cyclisation to give cycloalkanes and dehalogenation with hydrogen atom transfer to give alkenes in some cases. For 5-bromopent-1-ene the products are those expected from a radical pathway but for 6-bromohex-1-ene they are clearly not. For 2,2-dichloropropane and 1,1-dichloropropane elimination of HCl occurs but for 1,1-dichlorobutane, -pentane and -hexane partial hydrolysis followed by elimination of HCl gives E, E-, E,Z- and Z,Z- isomers of the dialk-1-enyl ethers and fully assigned 13C NMR data are presented for these. With 6-chlorohex-1-yne and 7-chlorohept-1-yne there is cyclisation to give methylenecycloalkanes and -cycloalkynes. The behaviour of 1,2-dibromocyclohexane and 1,2-dichlorocyclooctane under these conditions is also examined. Various pieces of evidence are presented that suggest that these processes do not involve generation of free gas-phase radicals but rather surface-adsorbed organometallic species.
Synthese von Propellanen (n = 2,3,4)
Fuchs, Josef,Szeimies, Guenter
, p. 2517 - 2522 (2007/10/02)
A facile access to the parent propellanes 2, 3 and 4 is presented.Lithiation of methallyl alcohol with BuLi/TMEDA complex and reaction of the organometallic intermediate 8 with parformaldehyde, ethylene oxide, or oxetane affords the diols 9 which are converted via the dichlorides 10 into tetrahalides 11.The cyclization of 11 to the corresponding propellanes is effected with 2 equiv. of MeLi or BuLi via bromobicyclobutanes 12.As expected, 2 cannot be isolated; its formation is deduced from the structure of the consecutive products.Key Words: Small-ring propellanes / Bicyclobutane bridging
Molecules with Twist Bent Bonds. The Synthesis, Properties, and Reactions of trans-Bicyclohept-3-ene and Certain Methylated Derivatives
Gassman, Paul G.,Bonser, Steven M.,Mlinaric-Majerski, Kata
, p. 2652 - 2662 (2007/10/02)
trans-Bicyclohept-3-ene, 7-methyl-trans-bicyclohept-3-ene, and 7,7-dimethyl-trans-bicyclohept-3-ene have been synthesized.Comparison of their ease of oxidation with the ease of oxidation of the analogous cis-bicyclohept-3-enes has been made.Both the thermal and transition-metal complex promoted rearrangements of the trans-bicyclohept-3-enes have been studied.These systems thermally convert to the cis-bicyclohept-3-enes above 100 deg C and are catalytically rearranged at ambient temperature.Trans to cis isomerization alsooccurs at ambient temperature under photoinduced single electron transfer conditions.
THE REDUCTION OF 2-VINYL-1,1-BIS(BROMOMETHYL)CYCLOPROPANE
Zefirov, N. S.,Kozhushkov, S. I.,Kuznetsova, T. S.,Sosonkin, I. M.,Domarev,A. M.,et al
, p. 1863 - 1873 (2007/10/02)
A study was carried out on the reduction of 2-vinyl-1,1-bis(bromomethyl)cyclopropane by various methods including electrochemical procedures.The major reaction pathways ential opening and expansion of the cyclopropane ring, while the product of the formation of a second three-membered ring, namely, vinylspiropentane, is formed in low yield.The probable radical mechanism for this reaction is discussed.
Deamination Reactions, 46. - Decomposition of 1-Alkenylcyclopropanediazonium Ions
Kirmse, Wolfgang,Rode, Klaus
, p. 839 - 846 (2007/10/02)
1-(2-Propenyl)- (10a), 1-(2-methyl-2-propenyl)- (10b), and 1-(3-butenyl)cyclopropanediazonium ions (35) have been generated by alkaline cleavage of the analogous nitrosocarbamates in methanol.Their major reaction paths are cyclopropyl-allyl tranformation (67 - 81percent), elimination to give alkylidenecyclopropanes (13 - 21percent), nucleophilic displacement (4 - 6percent), and 1,2-H shift (1 - 5percent).Participation of the double bond with formation of spirocyclic products was found to be small (0.5 - 1.2percent) with 10a, b and negligible with 35.The 2-methylene-5-hexenyl cations (39) arising from 35 underwent cyclization (intramolecular electrophilic addition, 39 --> 42) in competition with nucleophilic capture, but did not undergo a degenerate Cope rearrangement (39 39').
185-nm-Photochemie von Olefinen, gespannten Kohlenwasserstoffen und Azoalkanen in Loesung
Adam, Waldemar,Oppenlaender, Thomas
, p. 659 - 670 (2007/10/02)
Die Moeglichkeit, Chromophore, die nur im Vakuum-UV absorbieren, bei 185 nm direkt anzuregen, hat im letzten Jahrzehnt zur Belebung dieses Teilgebiets der Photochemie gefuehrt.Waehrend Reaktionen in der Gasphase bei λ220nm) treten bei 185-nm-Bestrahlung bevorzugt intramolekulare Umlagerungen, Spaltungen und Isomerisierungen auf, waehrend intermolekulare Radikalkupplungen und -abstraktionen sowie Dimerisierungen (?,?*-Anregung) nur geringfuegig konkurrieren.Neben der leicht moeglichen Denitrogenierung photoresistenter ("reluctant") Azoalkane zeichnen sich wichtige Anwendungsgebiete der kurzwelligen Photolyse auch in der Technik (Photolithographie) und der Medizin (193-nm-Laser) ab.Die Erweiterung des Synthesepotentials der 185-nm-Photochemie - bisher auf direkte cis/trans-Isomerisierungen beschraenkt -, ist eine Herausforderung fuer den Chemiker.
Methylenecyclohexenes: inversion barriers from the far-infrared spectra
Smithson, Tracy L.,Ibrahim, Nan,Wieser, Hal
, p. 442 - 453 (2007/10/02)
The far-infrared spectra of 3-methylenecyclohexene, 4-methylenecyclohexene, and 1-methyl-3-methylenecyclohexene in the region of 80-400 cm-1 are reported and interpreted mainly with a view to the two lowest out-of-plane deformations of the cycl
