cas 4453-90-1, 1,4-Dihydro-1,4-methanonaphthalene

Articles about 4453-90-1Total 38 be found

Article title
Article abstract
Author
Journal number and time
Download

Synthesis of (±)-cis-3-aminomethyl-1-tndanylmethanol as a precursor of carbocyclic analogues of nucleosides
Aminoalcohol precursor of carbocyclic analogues of nucleosides (±)-cis-3-aminomethyl-1-indanylmethanol was efficiently synthesized starting from benzonorbornadiene (5) previously prepared by addition of cyclopentadiene to 1-bromo2-fluorobenzene. Copyright
Escobar,Fernandez,Garcia-Mera,Rodriguez-Borges
p. 625 - 626
(1999)
Read Online

-
-
Adam,W.,Delucchi,O.
p. 2109
(1980)
Read Online

A CoMFA investigation of sigma receptor binding affinity: Reexamination of a spurious sigma ligand
A comparative molecular feld analysis (CoMFA) investigation was conducted on the binding of 64 compounds to σ1 receptors. Although CoMFA accurately predicted the binding affinities of the 64 compounds in the final set (R2 = 0.989), it was unable to predict the high affinity of the previously reported bridged σ ligand SC-50691. SC-50691, and its endo and exo isomers were synthesized and found to bind with much lower affinity than was previously reported.
Ablordeppey, Seth Y.,El-Ashmawy, Mahmoud,Fischer, James B.,Glennon, Richard A.
p. 625 - 633
(1998)
Read Online

New carbocyclic nucleosides derived from indan
Seven new carbocyclic nucleosides derived from indan (1a-g) were efficiently prepared from 1,2-indanedimethanol via Mitsunobu reaction with 6-chloroadenine and subsequent introduction of the appropriate substituent.
Abad,Alvarez,Fernandez,Garcia-Mera,Rodriguez-Borges
p. 1127 - 1128
(2001)
Read Online

Synthesis and cytostatic activities of new 6-substituted purinylcarbonucleosides derived from indan
A new series of 6-substituted purinylcarbonucleosides derivatives of indan, 8a-g and 10a-d, was synthesized from (±)-cis-1,3-indandimethanol acetate (5), which was prepared in three steps from benzonorbornadiene. 6-Chloropurine was introduced both by Mitsunobu reaction with 5 and by substitution of the mesylate 6. Suzuki-Miyaura reactions of the protected 6-chloropurine derivative 7 with substituted phenylboronic acids afforded 9a-d (protected purine derivatives with substituted phenyl rings at position 6); deprotection of the latter yielded the new series of purinylcarbonucleoside indan derivatives 10a-d. Treatment of compound 7 with R′H/NaOH afforded a parallel series 8a-g, with alkoxy or amino groups R′ at position 6 instead of substituted phenyl rings.
Fernandez, Franco,Garcia-Mera, Xerardo,Morales, Melvin,Rodriguez-Borges, Jose E.,De Clercq, Eric
p. 1084 - 1090
(2002)
Read Online

Iridium-Catalyzed Asymmetric Hydroalkenylation of Norbornene Derivatives
Transition-metal-catalyzed asymmetric hydroalkenylation of alkenes provides an atom-economical method to build molecular complexity from easily available materials. Herein we report an iridium-catalyzed asymmetric hydroalkenylation of unconjugated alkenes with acrylamides and acrylates. The catalytic hydroalkenylation of norbornene derivatives occurred to form products with allylic stereocenters with high chemo-, regio-, and stereoselectivities. DFT calculations revealed that the migratory insertion is irreversible and the enantiodetermination step.
Sun, Xin,Bai, Xiao-Yan,Li, An-Zhen,Li, Bi-Jie
supporting information
p. 2182 - 2187
(2021/03/01)

Cobalt(III)-Catalyzed Intermolecular Carboamination of Propiolates and Bicyclic Alkenes via Non-Annulative Redox-Neutral Coupling
A cobalt(III)-catalyzed, redox-neutral, intermolecular carboamination of propiolates and bicyclic alkenes was developed. This non-annulative coupling strategy features atom economy, high regioselectivity, good yields, and functional groups tolerance. Such a carboamination reaction was applied to modified phenols from the corresponding phenols under mild conditions.
Zhu, Yuelu,Chen, Feng,Zhao, Xinyang,Yan, Dingyuan,Yong, Wanxiong,Zhao, Jing
supporting information
p. 5884 - 5888
(2019/08/20)

Cycloaddition Reactions of Benzonorbornadiene and Homonorbornadiene: New Isoxazoline and Pyridazine Derivatives
Ten new isoxazoline derivatives were synthesized from the reactions of benzonorbornadiene and homonorbornadiene derivatives with nitrile oxides formed from benzaldehyde and 4-substituted benzaldehyde. Two new pyridazine derivatives were also synthesized from the reaction of the homonorbornadiene derivatives with 3,6-di (2-pyridyl)-s-tetrazine. It was seen that all cycloaddition reactions were realized as exo selectivity. Finally, γ-Gauche effect in the isoxazoline derivatives was discussed.
Adilo?lu, Yadigar,?ahin, Ertan,Tutar, Ahmet,Menzek, Abdullah
supporting information
p. 1917 - 1925
(2018/07/31)

Selective mono-alkylation of N-methoxybenzamides
We report our latest discovery of norbornene derivative modulated highly mono-selective ortho-C-H activation alkylation reactions on arenes bearing simple mono-dentate coordinating groups. The reaction features the use of readily available benzamides and alkyl halides. During the study, we prepared 30 mono-alkylated aryl amides in good yields with good mono-selectivity. We have also demonstrated that structurally rigid alkenes such as norbornene and its derivatives are a good class of ligand and could be used for future direct C-H functionalizations. The utilization of norbornene type ligands for assistance in C-H activation processes has opened a new window for future molecular design using direct C-H functionalization strategies.
Chen, Zenghua,Hu, Le'an,Zeng, Fanyun,Zhu, Ranran,Zheng, Shasha,Yu, Qingzhen,Huang, Jianhui
supporting information
p. 4258 - 4261
(2017/04/21)

KO:TBu-Catalyzed lithiation of PMDTA and the direct functionalization of bridged alkenes under mild conditions
A practical preparation of the reagent PMDTALi using a super base system under mild conditions has been developed. This PMDTALi base has been demonstrated to be a very efficient reagent for the lithiation of bridged alkenes via direct deprotonation. Further reactions with electrophiles and also coupling reactions in the presence of Pd catalysts provide the bridged alkenes with a broad range of functional groups including silyl, alkyl, halogen and aryl substituents. The utilization of this new lithium reagent has brought a new diversity to the choice of lithium reagent for the deprotonation of synthetically challenging systems.
Wang, Yuntao,Liu, Jialin,Huang, Lin,Zhu, Ranran,Huang, Xueyan,Moir, Ross,Huang, Jianhui
supporting information
p. 4589 - 4592
(2017/04/28)

Comparison of alkene hydrogenation in carbon nanoreactors of different diameters: Probing the effects of nanoscale confinement on ruthenium nanoparticle catalysis
The catalytic properties of ruthenium nanoparticles (RuNPs) supported in carbon nanoreactors of different diameters-single walled carbon nanotubes (SWNTs, width of cavity 1.5 nm) and hollow graphitised nanofibers (GNFs, width of cavity 50-70 nm)-were evaluated using exploratory alkene hydrogenation reactions and compared to RuNPs adsorbed on the surface of SWNT or deposited on carbon black in commercially available Ru/C. Supercritical CO2 is shown to be essential to enable efficient transport of reactants to the catalytic RuNPs, particularly for the very narrow RuNP@SWNT nanoreactors. Though the RuNPs in SWNT are observed to be highly active, they simultaneously reduce the accessible volume of very narrow SWNTs by 30-40% resulting in lower overall turnover numbers (TONs). In contrast, RuNPs confined in wider GNFs were completely accessible and demonstrated remarkable activity compared to unconfined RuNPs on the outer surface of SWNTs or carbon black. Control of the nanoscale environment around the catalytic RuNPs significantly enhances the stability of the catalyst and influences the local concentration of reactant molecules in close proximity to the RuNPs, illustrating the comparable importance of confinement to that of metal loading and size of NPs in the catalyst. Interestingly, extreme spatial confinement also appeared not to be the best strategy for controlling the selectivity of hydrogenations in a competitive reaction of norbornene and benzonorbornadiene, with wider RuNP@GNF nanoreactors displaying enhanced selectivity for the hydrogenation of the aromatic group containing alkene (benzonorbornadiene). This is attributed to the presence of nanoscale graphitic step-edges within the GNF making them an attractive alternative to the extremely narrow SWNT nanoreactors for preparative catalysis.
Aygün, Mehtap,Stoppiello, Craig T.,Lebedeva, Maria A.,Smith, Emily F.,Gimenez-Lopez, Maria Del Carmen,Khlobystov, Andrei N.,Chamberlain, Thomas W.
p. 21467 - 21477
(2017/10/23)

Diastereoselective [3+2] Annulation of Aromatic/Vinylic Amides with Bicyclic Alkenes through Cobalt-Catalyzed C-H Activation and Intramolecular Nucleophilic Addition
A highly diastereoselective method for the synthesis of dihydroepoxybenzofluorenone derivatives from aromatic/vinylic amides and bicyclic alkenes is described. This new transformation proceeds through cobalt-catalyzed C-H activation and intramolecular nucleophilic addition to the amide functional group. Transition-metal-catalyzed C-H activation reactions of secondary amides with alkenes usually lead to [4+2] or [4+1] annulation; to the best of our knowledge, this is the first time that a [3+2] cycloaddition is described in this context. The reaction proceeds under mild conditions and tolerates a wide range of functional groups. Mechanistic studies imply that the C-H bond cleavage may be the rate-limiting step. [3+2] instead of [4+2] or [4+1]: The diastereoselective [3+2] annulation of secondary amides with alkenes proceeds by cobalt-catalyzed C-H activation and intramolecular nucleophilic addition to the amide functional group under mild conditions. Mechanistic studies suggest that the C-H bond cleavage is the rate-limiting step.
Gandeepan, Parthasarathy,Rajamalli, Pachaiyappan,Cheng, Chien-Hong
supporting information
p. 4308 - 4311
(2016/04/01)

Highly flexible synthesis of indenylethylamines as ligand precursors for titanium complexes
Various indenylethylamines are synthesized for the first time by reductive amination of 2-(1H-inden-1-yl)acetaldehyde with commercially available primary amines. In addition, a new two-step synthesis of 2-(1 H-inden-1-yl)acetaldehyde that uses inexpensive indene and 2-bromo-1,1-diethoxyethane as starting materials is presented. Finally, a selected indenylethylamine is used as a ligand precursor for the synthesis of a corresponding indenylethylamido titanium complex. The latter result paves the way for applications of corresponding complexes as catalysts for important chemical reactions.
Ross, Jan H.,Rohjans, Stefan H.,Schmidtmann, Marc,Doye, Sven
p. 76 - 96
(2015/04/22)

Copper-catalyzed enantioselective formal hydroamination of oxa- and azabicyclic alkenes with hydrosilanes and hydroxylamines
A CuCl/(R,R)-Ph-BPE-catalyzed enantioselective formal hydroamination of oxa- and azabicyclic alkenes with polymethylhydrosiloxane (PMHS) and O-benzoylhydroxylamines has been developed. The efficient and stereoselective net addition of hydrogen and nitrogen atoms provides the corresponding optically active oxa- and azanorbornenyl- and -norbornanylamines in good yields and good enantiomeric ratios.
Miki, Yuya,Hirano, Koji,Satoh, Tetsuya,Miura, Masahiro
supporting information
p. 1498 - 1501
(2014/04/03)

Batch versus flow photochemistry: A revealing comparison of yield and productivity
The use of flow photochemistry and its apparent superiority over batch has been reported by a number of groups in recent years. To rigorously determine whether flow does indeed have an advantage over batch, a broad range of synthetic photochemical transformations were optimized in both reactor modes and their yields and productivities compared. Surprisingly, yields were essentially identical in all comparative cases. Even more revealing was the observation that the productivity of flow reactors varied very little to that of their batch counterparts when the key reaction parameters were matched. Those with a single layer of fluorinated ethylene propylene (FEP) had an average productivity 20% lower than that of batch, whereas three-layer reactors were 20% more productive. Finally, the utility of flow chemistry was demonstrated in the scale-up of the ringopening reaction of a potentially explosive [1.1.1] propellane with butane-2,3-dione.
Elliott, Luke D.,Knowles, Jonathan P.,Koovits, Paul J.,Maskill, Katie G.,Ralph, Michael J.,Lejeune, Guillaume,Edwards, Lee J.,Robinson, Richard I.,Clemens, Ian R.,Cox, Brian,Pascoe, David D.,Koch, Guido,Eberle, Martin,Berry, Malcolm B.,Booker-Milburn, Kevin I.
supporting information
p. 15226 - 15232
(2015/02/05)

The role of chirality in directing the formation of cup-shaped porphyrins and the coordination characteristics of such hosts
Cup-shaped porphyrin 1a has four norbornane rings for encircling space and this type of host could be of interest in supramolecular and catalytic chemistry. We used 1H NMR spectroscopy to investigate the acid-catalyzed (pTsOH in CHCl3 and TFA in CH3CN) condensation of racemic, enantioenriched (80-85% enantiomeric excess (ee)), and enantiopure (99% ee) pyrromethanecarbinol 7 into 1a. We found that the oligomerization of racemic 7rac would give 1a-d in the ratio different from the statistical one, though a minuscule quantity of 1a (95% diastereomeric excess (de), 25% overall yield) in CHCl3 although prolonged reaction times or greater concentration of the catalytic acid gave rise to 1b-d at the expense of 1a. The metallation of 1a with Zn(OAc) 2 led to the formation of ZnII-1a and we used computational (DFT: RI-BP86/SV(P),TZVP) and experimental (1H NMR spectroscopy) methods to study the partitioning of smaller N-methylimidazole 13 (94 A3) and bigger 1,5-dicyclohexylimidazole 14 (268 A3) between the inner and outer side of the host. We found that bigger 14 was mostly encapsulated (90%) inside ZnII-1a at 298.0 K, whereas smaller 13 would equally partition between the two sides of the host. Furthermore, the out/in equilibrium was, in the case of 14-ZnII-1a, favored by entropy (TΔS°out/in=3.5±0.1 kcalmol -1) indicating that perhaps differential solvation of the coordinated ligand assisted the encapsulation.
Wang, Bao-Yu,Turner, Daniel A.,Zujovic, Teodora,Hadad, Christopher M.,Badjic, Jovica D.
supporting information; experimental part
p. 8870 - 8881
(2011/09/16)

PROCESSES FOR THE PREPARATION OF VARENICLINE AND INTERMEDIATES THEREOF
The invention provides an improved process for the preparation and purification of Varenicline and intermediates for the preparation of Varenicline.
-
Page/Page column 7-8

(2009/12/28)

Synthesis and Diels-Alder cycloaddition reaction of norbornadiene and benzonorbornadiene dimers
Dimeric forms of norbornadiene and benzonorbornadiene were synthesized starting with known monobromide derivatives. The Diels-Alder cycloaddition reaction of dimers with TCNE and PTAD was investigated and new norbornenoid polycyclics were obtained. All co
Nisanci, Bilal,Dalkilic, Erdin,Gueney, Murat,Dastan, Arif
experimental part

(2010/04/22)

Formation of 3-halobenzyne: Solvent effects and cycloaddition adducts
Noncoordinating solvents permit the halogen-metal exchange-induced formation of benzyne (aryne) from di- and trihalobenzene precursors in the presence of cyclopentadiene to give 1,4-dihydro-1,4-methano-naphthalenes. Studies with mixed halide precursors and nonacidic Diels-Alder diene traps reveal that ethereal and hydrocarbon solvents influence the halide leaving group facility, resulting in a reversal of 3-halobenzyne regioselectivity.
Coe, Jotham W.,Wirtz, Michael C.,Bashore, Crystal G.,Candler, John
p. 1589 - 1592
(2007/10/03)

Synthesis of 2,3,4,5-tetrahydro-1,5-methano-1H-3-benzazepine via oxidative cleavage and reductive amination strategies
Preparations of 2,3,4,5-tetrahydro-1,5-methano-1H-3-benzazepine (5) from benzonorbornadiene (1) by oxidative cleavage and reductive amination sequences were investigated. Osmium-mediated dihydroxylation of 1 followed by NaIO 4 cleavage, reductive amination and debenzylation provides 5 in 64-73% yield overall in three operations. A tandem ozonolysis-reductive amination procedure gives 5 as the tosylate salt from benzonorbornadiene with no isolation of intermediates in 28% yield.
Brooks, Paige R.,Caron, Stephane,Coe, Jotham W.,Ng, Karl K.,Singer, Robert A.,Vazquez, Enrique,Vetelino, Michael G.,Watson Jr., Harry H.,Whritenour, David C.,Wirtz, Michael C.
p. 1755 - 1758
(2007/10/03)

Dehalogenation of o-dihalogen substituted arenes and α,α′-dihalogen substituted o-xylenes with lanthanum metal
It was found that lanthanum metal caused the dehalogenation of o-dihalogen substituted arenes and α,α′-dihalogen substituted o-xylenes to generate the corresponding benzynes and o-quinodimethanes. When o-dihalogen substituted arenes were allowed to react with lanthanum metal in the presence of dienes, the Diels-Alder products between benzyne and dienes were formed in moderate to good yields. Similarly, the Diels-Alder adducts of o-quinodimethane with dienophiles were obtained, in the reaction of α,α′-dibromo-o-xylenes with lanthanum metal in the presence of dienophiles.
Nishiyama, Yutaka,Kawabata, Hiroshi,Nishino, Toshiki,Hashimoto, Kouji,Sonoda, Noboru
p. 6609 - 6614
(2007/10/03)

Reaction of 1,2-dihalogen substituted arenes with lanthanum metal: A new generation method of benzyne
A new generation method of benzyne has been developed. When 1,2-dihalogen substituted arenes were allowed to react with lanthanum metal in the presence of dienes, Diels-Alder products between benzyne and dienes were formed in moderate to good yields.
Kawabata, Hiroshi,Nishino, Toshiki,Nishiyama, Yutaka,Sonoda, Noboru
p. 4911 - 4913
(2007/10/03)

A mild alternative to the use of benzyne in [4 + 2]-cycloaddition reactions
A synthetic protocol to assemble a benzene ring, mimicking the [4 + 2]-cycloaddition of benzyne is reported. The sequence of reactons is made up of simple and mild steps and overall it furnishes comparable or even better yields with respect to the direct addition of benzyne.
Cossu, Sergio,De Lucchi, Ottorino
p. 14247 - 14252
(2007/10/03)

The Dechlorination of Some Highly Chlorinated Naphthalene Derivatives
The cycloadducts formed between tetrachlorobenzyne and a variety of arenes and cyclic 1,3-dienes have been reductively dechlorinated.The products are formally benzyne cycloadducts, many of which are difficult to make by other routes.High yields are obtained when sodium and t-butanol in boiling THF are used for the reduction.THF serves as a solvent but t-butanol not only acts as a proton donor but also appears to initiate the reduction.Tetrachlorobenzyne should be considered as an alternative reagent whenever benzyne itself appears to be required.
Hales, Neil J.,Heaney, Harry,Hollinshead, John H.,Lai, Steven M. F.,Singh, Pritpal
p. 7777 - 7790
(2007/10/02)

An examination of β-enolization in benzobicyclo[2.2.2], [3.2.1], and [3.2.2] ketones
-
Muir,Stothers
p. 1290 - 1296
(2007/10/02)

1,2,4-Cylohexatrien, ein Isobenzol, und Bicyclodeca-1,3,5,7,8-pentaen, ein Isonaphthalin: Erzeugung und Abfangreaktionen
-
Christl, Manfred,Braun, Martin,Mueller, Germar
p. 471 - 473
(2007/10/02)

Ethanobicyclic amine derivatives for CNS disorders
Certain ethanobicyclic amine compounds are described for treatment of CNS disorders such as psychotic disorders, convulsions, dystonia and cerebral ischemia. Compounds of particular interest are of the formula STR1 wherein each of R1, R2, R3, R4, Y and Z is independently selected from hydrido, hydroxy, alkyl, cycloalkyl, cycloalkylalkyl, phenalkyl, phenyl, alkoxy, phenoxy, phenalkoxy, alkoxyalkyl, halo, haloalkyl and hydroxyalkyl; wherein R3 and R4 may be taken together to form oxo; wherein each of R5, R6, R7, R8, R9 and R10 is independently selected from hydrido, alkyl, cycloalkyl, hydroxyalkyl, fluoroalkyl, cycloalkylalkyl, alkoxyalkyl, phenalkyl and phenyl; wherein G within the nitrogen-containing cyclohetero moiety is selected from STR2 wherein R11 is selected from hydrido, alkyl, cycloalkyl, cycloalkylalkyl, phenyl, phenalkyl, alkoxyalkyl and hydroxyalkyl wherein each of R12 and R13 is independently selected from hydrido, hydroxy, alkyl, phenalkyl, phenyl, alkoxy, fluoroalkyl and fluoro; wherein m is one or two; wherein p is a number selected from zero through four, inclusive; wherein each of q and r is a number independently selected from one through three, inclusive, with the proviso that sum of q and r is a number from three through six, inclusive; with the further proviso that the nitrogen-containing cyclohetero moiety must be attached at one position selected from R3, R4, ring-position two, and ring-position three; or the pharmaceutically-acceptable salts thereof.
-
(2008/06/13)

A novel palladium-catalyzed deoxygenation of enediols to 1,3-dienes
Hydroxylative Knoevenagel condensation of aldehydes followed by reduction provides a simple entry to 1,4-enediols. Subjecting the dicarbonate to a palladium(0) catalyst in the presence of triisopropyl phosphite achieves a mild vinylogous deoxygenation to (E)-1,3-dienes. Stereocontrolled synthesis of the sex pheromone of the red bollworm moth, (E)-9,11-dodecadienyl acetate, and a formal synthesis of the cotton boll weevil antifeedant, α-eleostearic acid, demonstrate the utility of this new methodology.
Trost,Tometzki
p. 1235 - 1245
(2007/10/02)

Umpolung of ?-Allylpalladium Intermediates. A Chemoselective Reductive Elimination of Diols
-
Trost, Barry M.,Tometzki, Gerald B.
p. 915 - 917
(2007/10/02)

Benzonorbornene derivatives, processes for their preparation and medicinal and cosmetic compositions containing them
A compound of formula (I) STR1 its isomers and its salts in which --R1, R3 and R4 are each indepenently hydrogen, C1 -C8 -alkyl, C1 -C8 -alkoxy, halogen, C1 -C8 -acyloxy or hydroxyl; --R' is hydrogen or C1 -C6 -alkyl; --R" is either a polyene chain or a benzene ring are useful in cosmetics and in the treatment of various dermatological and other complaints.
-
(2008/06/13)

WagnerMeerwein Rearrangements of radical Cations Generated by Triphenylpyrylium Tetrafluoroborate Photosensitized Electron Transfer of Azoalkanes
-
Adam, Waldemar,Doerr, Markus
p. 1570 - 1572
(2007/10/02)

Photolytic Cleavage of Remote Functional Groups in Polyfunctional Molecules. Photolysis of exo- and endo-Benzobicycloocten-2-yl Chloride
The aryl-induced photolytic cleavage of a remote C-Cl bond, earlier reported for the 2-position in the benzonorbornenyl series, is extended to the 2-position of the title compounds (exo-BBCl and endo-BBCl).Cleavage with 254-nm excitation is an efficient reaction (ψdis = 0.45 and 0.005, exo and endo, respectively), involving the aryl singlet excited state.Radical and carbocation derived products are observed (eq.3), with the latter including an olefin (8), a cyclopropane (9), and rearranged ethers (10 and 13) attributed to "hot" cation intermediates.The rate constants for C-Cl cleavage sre as follows: exo 1.1*109 s-1; exo 2.2.2>, 3.8*108 s-1; endo , 1.7*106 s-1; endo , 2.7*105 s-1.These rates are discussed within the context of previously proposed mechanisms.
Morrison, Harry,Muthuramu, Kayambu,Pandey, Genesh,Severance, Daniel,Bigot, Bernard
p. 3358 - 3363
(2007/10/02)

Photolytic Cleavage of Remote Functional Groups in Polyfunctional Molecules. Photolysis of exo- and endo-2-Benzonorbornenyl Chlorides and Methanesulfonates
The photochemistry and photophysics of the title compounds are reported.The exo chloride exhibits a facile cleavage of the C - Cl bond upon excitation of the aryl chromophore (eq 1 - 3).The reaction has a rate > 700-fold larger than that observed with the endo isomer, derives from the singlet excited state, and leads to the formation of "hot" carbocations as well as free radicals.The exo mesylate shows similar characteristics (eq 4).A mechanism (Scheme II) is suggested which incorporates both heterolytic fission as well as sequential homolytic fission (to a polarized radical pair), followed by electron transfer to form an ion pair.The stereoelectronically controlled activation of the C - Cl and C - OMs moieties is explaned by a correlation diagram (Figure 5) which depicts the ?,?* state as correlating with the diradical product state through an avoided crossing with the C - X ?,?* state.Calculations indicate that this avoided crossing is considerably larger (and the barrier to reaction therefore considerably smaller) when the C - X unit in the 2-benzonorbornenyl series is exo.
Morrison, Harry,Miller, Alan,Bigot, B.
p. 2398 - 2408
(2007/10/02)

Regioselectivities in the Di-?-methane Photorearrangement of 2-Methylbenzonorbornadienes Carrying Methoxy- and Cyanoaryl Substituents. The Vinyl Methyl Effect
The triplet-state photoisomerisations of 2-methylbenzonorbornadiene and all eight possible aryl cyano- and methoxy-substituted derivatives have been investigated.The parent hydrocarbon underwent di-?-methane rearrangement with preferential (81 percent) benzo-vinyl bridging to C-3 (β bridging).The 5-CH3O, 6-CH3O, 5-CN, and 7-CN examples represent cases where the substituent effects should work cooperatively, and a single photoproduct was formed in each instance.In the remaining four examples, the substituents are positioned to direct in an antagonist fashion.Interestingly, the product ratios for the 7-CH3O and 7-CN systems are within experimental error of those determined on the basis of perfect substituent additivity effects.As concerns the 8-CH3O and 8-CN derivatives, the apparent directing effect of methyl for β/α bridging is seen to be slightly higher (96:4) than usual.Probable causes for this phenomenon are presented.Because of its role as a moderate controller of excited-state regioselectivity, the methyl substituent has proven to be a useful probe of such reactions.Synthetic approaches to the alkyl-substituted benzonorbornadienes are also detailed.
Paquette, Leo A.,Bay, Elliott,Yeh Ku, Audrey,Rondan, Nelson G.,Houk, K. N.
p. 422 - 428
(2007/10/02)

PHOTOCHEMISTRY OF BENZOTRICYCLO2,7>HEPTENE: SINGLET EXCITED STATE REACTIONS DERIVED FROM CYCLOPROPANE RING CLEAVAGE
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.
Johnson, Richard P.,Davis, Katherine Schlimgen
p. 3171 - 3174
(2007/10/02)

Generation of 2,3-Benzobicyclo<2.2.1)hept-2-ene-5,7-diyl Diradicals via Denitrogenation of Appropriate Azoalkanes and Their Mechanistic Implications in the Di-?-methane Rearrangement of Benzonorbornadienes
The azoalkanes 16a-c, prepared from the bicycloalkadienes 5a-c via dipolar cycloaddition with 4-methyl-1,2,4-triazoline-3,5-dione (MTAD) and subsequent oxidative hydrolysis, were submitted to thermal and direct and ketone-sensitized photochemical denitrogenation, with the intention of entering the diradical manifold postulated for the di-?-methane rearrangement.It is shown that in each case denitrogenation leads to the expected 2,3-benzobicyclohept-2-ene-5,7-diyl diradical 7.Diradical 7 mostly cyclizes into the corresponding tricycloalkene 8, and only a very small fraction (5percent) suffers retro-di-?-methane rearrangement into the bicycloalkadiene 5 via the cyclopropyl dicarbinyl radical 6.Stabilizing substituents such as benzhydryl and spirocyclopropyl groups in a position α to the rearranging radical site in 7 discourage retro-di-?-methane reaction.
Adam, Waldemar,Lucchi, Ottorino De
p. 4133 - 4138
(2007/10/02)

THE PHOTOCHEMISTRY OF BENZOTRICYCLO2,6>HEX-3-ENE
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.
Kouwenhoven, Arjan P.,Noort, Paul C. M. van,Cerfontain, Hans
p. 1745 - 1748
(2007/10/02)

UNTERSUCHUNGEN ZUM THERMISCHEN UND PHOTOCHEMISCHEN VERHALTEN VON 8,9-DIAZA-4,5-BENZOTRICYCLO3,7>OCTA-4,8-DIEN
Die direkte Photolyse der Titelverbindung 1 verlaeuft erwartungsgemaess unter Stickstoffabspaltung zu 6.Dagegen fuehrt ihre Thermolyse und ihre sensibilisierte Bestrahlung zu den ueberraschenden Produkten 4 bzw. 8, deren spektroskopische Charakterisierung und moegliche Bildungsmechanismen diskutiert werden.
Erden, Ihsan,Balci, Metin
p. 1825 - 1828
(2007/10/02)

Intramolecular Aryl-Assisted Photolytic Cleavage of 2-Benzonorbornenyl Derivatives. A High Excited-State Exo/Endo Reactivity Ratio and a Novel Wagner-Meerwein Rearrangement
-
Morrison, Harry,Miller, Alan
p. 372 - 373
(2007/10/02)