Synthesis of porphyrin dimers fused with a benzene unit

Bicyclo[2.2.2]octadiene-connected pyrrolo-porphyrins have been prepared by an inverse-type [3+1] porphyrin synthesis of a bicyclo[2.2.2]octadiene-fused dipyrrole with a tripyrrane dicarbaldehyde. Another [3+1] porphyrin synthesis of pyrrole-connected porphyrins with the same or other tripyrrane dicarbaldehydes gave bicyclo[2.2.2]octadiene-bridged diporphyrins, the central metals and/or peripheral substituents of which were different. Thermal decomposition of the bicyclo[2.2.2]octadiene skeleton to a benzene moiety gave pi-system-fused porphyrin dimers in a highly pure form.     

Oxidative Dearomatization: Synthesis of Functionalized Bicyclo[2.2.2]octenones,Sigmatropic Shift in Excited State,and Radical-Induced Cleavage of Cyclopropane Ring

Synthesis of novel bicyclo[2.2.2]octenones endowed with a β,γ-enone system in which γ-carbon is substituted with an electron-withdrawing group from simple aromatics is described. Oxa-di-pi-methane reaction of bicyclo[2.2.2]octenones to functionalized bicyclo[3.3.0]octanes and their transformation to bicyclo[3.2.1]octane framework are also presented.     

Polyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings

Polyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings are prepared from 1,4-bis(carboethoxy)bicyclo[2.2.2]octane, 1,4-bis(hydroxymethyl)bicyclo[2.2.2]-octane and the 1,5-disubstituted bicyclo[3.2.2]nonane analogs. These polyesters are compared to the related polymers containing 1,4-phenylene and trans-1,4-cyclohexylene rings in terms of their melting point, thermal stabilities and oxidative stabilities. The lower symmetry of the bicyclo[3.2.2]nonane ring produces lower-melting polymers than the other ring systems. The remaining three rings are approximately equivalent in their effect on the melting point of a polymer provided that no more than one bicyclo[2.2.2]octane ring is present per polymer repeat unit. Two such rings produce a highermelting polymer than any other combination. Both the thermal and oxidative stabilities of the polyesters is improved by the presence of the bicyclo rings. This is attributed to the rings providing an approximation of a ladder polymer.     

Cycloaddition between electron-deficient pi-systems, photochemical and radical-induced reactions: a novel, general, and stereoselective route to polyfunctionalized bridged bicyclo[2.2.2]octanes, bicyclo[3.3.0]octanes, bicyclo[4.2.0]octanes, and tricyclo[4.3.1.0(3,7)]decanes

A novel, general, and stereoselective route to functionalized bridged bicyclo[2.2.2]octanes, bicyclo[3.3.0]octanes, bicyclo[4.2.0]octanes, and tricyclo[4.3.1.0(3,7)]decanes has been described. Various functionalized and substituted bicyclo[2.2.2]octanes endowed with a beta,gamma-enone chromophore were synthesized via cycloaddition of in situ generated cyclohexa-2,4-dienones with electron-deficient 2pi partners and manipulation of the resulting adducts. Triplet sensitized irradiation of bridged bicyclooctenones led to synthesis of bicyclo[3.3.0]octanoids, whereas the direct irradiation furnished bicyclo[4.2.0]octanes in stereoselective fashion as a result of modulation of reactivity in excited states. Further, manipulation of the adducts led to appropriately appended and functionalized bicyclo[2.2.2]octanes that upon radical induced cyclization provided an efficient and stereoselective route to the tricyclo[4.3.1.0(3,7)]decane (isotwistane) framework of pupukeananes.     

Novel bicyclo[2.2.2]octanyl-1,4-benzodiazepinones. Their syntheses and rearrangement to bicyclooct-2-enylbenzimidazoles

The synthesis of the novel bicyclo[2.2.2]octanyl[1,4]benzodiazepinone ring system (IV) and its facile acid catalysed rearrangement to the corresponding bicyclo[2.2.2]oct-2-enylbenzirnid-azole system (IX) is described.     

The stepwise heats of hydrogenation of barrelene,an ab initio study

Ab initio Hartree-Fock calculations at the 6–31G*//3–21G level of theory are reported for bicyclo[2.2.2]-2,5,7-octatriene (barrelene), 1 , bicyclo[2.2.2]-2,5-octadiene, 2 , bicyclo[2.2.2]-2-octene, 3 , and bicyclo-[2.2.2]octane, 4 . The stepwise heats of hydrogenation of 1 were found to be 38.1, 31.8, and 28.4 kcal/mol, respectively. The unusually large heat of hydrogenation for the first double bond is attributed to the destabilizing electronic effects involving the interaction of the three double bonds of 1 .     

4-Aminobicyclo[2.2.2]octanone Derivatives with Antiplasmodial and Antitrypanosomal Activities

4-Aminobicyclo[2.2.2]octanones were converted to their N-oxides and to 4-aminobicyclo[2.2.2]octanes. Furthermore, the 6,7-bis-(4-methoxyphenyl) analogues were synthesized. All products were screened for their activities against Trypanosoma b. rhodesiense and Plasmodium falciparum. The pharmacological results were compared with those of formerly tested bicyclo[2.2.2]octanones and bicyclo[2.2.2]octanols. Structure-activity relationships are discussed.     

Retro-Diels-Alder reaction using bicyclo[2.2.2]octatriene-fused pyrrole during porphyrin synthesis

Porphyrin synthesis using 4,7-etheno-4,7-dihydro-2H-isoindole and tripyrranedicarbaldehyde gave a porphyrin derivative bearing no bicyclo[2.2.2]octatriene moiety as well as the targeted bicyclo[2.2.2]octatriene-fused porphyrin.     

Cycloaddition of cyclohexa-2,4-dienones with β-nitroacrylates: a short and efficient entry into bicyclo[2.2.2]octanes endowed with β-nitro-ester and β-amino ester functionality

Regio- and stereoselective cycloaddition of β-nitroacrylates with electron deficient cyclohexa-2,4-dienones leading to highly functionalised bicyclo[2.2.2]octanes having the β-nitroester group and their transformation to bicyclo[2.2.2]octanes having β-aminoester functionality is described.     

Diels-Alder reactions of 4-triflyloxy-2,6,6-trimethyl-2,4-cyclohexadienone. An expedient methodology for the synthesis of bicyclo[2.2.2]oct-5-en-2-ones and bicyclo[2.2.2]octa-5,7-dien-2-ones

The synthesis of 4-triflyloxy-2,6,6-trimethyl-2,4-cyclohexadienone (13), bicyclo[2.2.2]octenones 1a-j and 15a-j, and bicyclo[2.2.2]octadienones 2a-f, 6a-d, and 11a-f is described. The 2,4-cyclohexadienones 4 and 13 were used for the first time as nondimerizing and easily accessible alternatives to 2,6,6-trimethyl-2,4-cyclohexadienone 12 in Diels-Alder reactions with acetylene derivatives 5a-d to prepare the adducts 6a-d and 11a-e in excellent yields. Compounds 11a-d were initially prepared by the alcoholysis of 6a-d to afford bicyclo[2.2.2]octene-2,5-diones 7a-dfollowed by treatment of 7a-d with N-phenyltriflimide in the presence of LHMDS at -78 degrees C. Diels-Alder reaction of 13 with an acetylene equivalent, phenyl vinyl sulfoxide, was also studied. A detailed study of the Diels-Alder reactions of various olefinic dienophiles 14a-j with 13 has been carried out to furnish cycloadducts 15a-j in high yields. Reductive removal of triflyloxy group of vinyl triflates 11a-f and 15a-j was performed in the presence of [Pd(PPh(3))(2)Cl(2)-Bu(3)N-HCO(2)H] to obtain the desired bicyclo[2.2.2]octadienones 2a-f and bicyclo[2.2.2]octenones 1a-j, respectively, in good overall yields.     

Thermotropic homopolyester. I. Synthesis and characterization of homopolyesters containing the mesogenic unit,bicyclo[2.2.2]oct-2-ene

Homopolyesters based on bicyclo[2.2.2]oct-2-ene as a mesogenic group were prepared and characterized. The use of bicyclo[2.2.2]oct-2-ene in these homopolyesters lowered the symmetry of the resulting systems enough to lead to the observation of melting behavior.     

Synthesis of molecular motors incorporating para-phenylene-conjugated or bicyclo[2.2.2]octane-insulated electroactive groups

The insulating role of the bicyclo[2.2.2]octane fragment has been theoretically evaluated by comparing the electronic coupling parameter (V(ab)) in 1,4-bis(ferrocenyl)benzene (1) and 1,4-bis(ferrocenyl)bicyclo[2.2.2]octane (2). The geometries were optimized by DFT and an extended Hückel calculation was performed to evaluate V(ab) by the dimer splitting method. The calculations showed a 12-fold decrease of the electronic coupling from 60 meV for 1 to 5 meV for 2. The second part describes the synthesis of two potential molecular motors with one incorporating the insulating bicyclo[2.2.2]octane fragment. These molecules are based on a ruthenium complex bearing a tripodal stator functionalized to be anchored onto surfaces. The ferrocenyl electroactive groups and the cyclopentadienyl (Cp) rotor are connected through a p-phenylene spacer (5) or through a spacer incorporating an insulating bicyclo[2.2.2]octane moiety (6).     

4-Aminobicyclo[2.2.2]octanone Derivatives with Antiplasmodial and Antitrypanosomal Activities

Summary. 4-Aminobicyclo[2.2.2]octanones were converted to their N-oxides and to 4-aminobicyclo[2.2.2]octanes. Furthermore, the 6,7-bis-(4-methoxyphenyl) analogues were synthesized. All products were screened for their activities against Trypanosoma b. rhodesiense and Plasmodium falciparum. The pharmacological results were compared with those of formerly tested bicyclo[2.2.2]octanones and bicyclo[2.2.2]octanols. Structure-activity relationships are discussed.Received April 8, 2003; accepted April 14, 2003 Published online September 25, 2003     

Cycloaddition of cyclohexa-2,4-dienones with electron deficient 2 pi partners: a novel and stereoselective route to functionalized bicyclo[2.2.2]octenones

A novel route to functionalised bicyclo[2.2.2]octenones via pi 4s + pi 2s cycloaddition of cyclohexa-2,4-dienones with electron deficient 2 pi partners, and crystal structure of 1,7-dimethyl-5-hydroxy-5-chloromethyl-2-carboethoxy bicyclo[2.2.2]oct-7-ene-6-one, is reported.     

Autocatalytic domino Michael reaction leading to bicyclo[2.2.2]octane-2,5-dione derivatives

In the presence of a catalytic amount of lithium amide, the reaction of oxophorone with electron-deficient olefins afforded bicyclo[2.2.2]octane-2,5-dione derivatives in high yields. The reaction proceeds autocatalytically by an enolate of bicyclo[2.2.2]octane-2,5-dione, generated by an initial domino Michael reaction.     

Trimethylsilyl group directed wagner-meerwein rearrangement of bicyclo[2.2.2]octan-2-ol derivatives

Trimethylsilyl group substituted bicyclo[2.2.2]octane derivatives were synthesized and subjected to TMS group directed Wagner-Meerwein rearrangement to give bicyclo[3.2.1]octene derivatives in high yields.     

Tandem radical rearrangement/Pd-catalysed translocation of bicyclo[2.2.2]lactones. An efficient access to the oxa-triquinane core structure

The skeletal rearrangement of bicyclo[2.2.2]lactones, involving a mild and chemoselective palladium-catalysed translocation key-step, provides an efficient and diastereoselective access to synthetically useful bicyclo[3.3.0]lactones.     

Mechanism of interaction of substituents in bicycloalkane compounds

The mechanism of interaction of substituents in the 4-substituted bicyclo[2.2.2]oct-1-ylfluorides and bicyclo[2.2.1]hept-1-ylfluorides based on the inductive effect and the positive charge effect was studied.     

Domino ring-opening metathesis-ring-closing metathesis of bicyclo[2.2.2]octene derivatives: scope and limitations

Domino metathesis involving ring-opening metathesis-ring-closing metathesis (ROM-RCM) of a bicyclo[2.2.2]octene derivative having an appropriate alkene chain, expected to produce a 7/6 fused bicyclic system, provided a decalin system in contrast to ROM-RCM of the corresponding bicyclo[2.2.1]heptene analogues, which as expected produced the 7/5 fused bicycles. The expected 6/7 bicyclic system could, however, be made through RCM of the elusive ROM product prepared from the same bicyclo[2.2.2]octene analogue by a nonmetathetic route. A rationale to explain the difference in reactivity pattern between these two systems toward ROM-RCM has been forwarded.     

A New Route to the Synthesis of 7-Functionalised Bicyclo[2.2.1]Heptane Derivatives

A new route to the synthesis of 7-functionalised bicyclo[2.2.1]heptane derivatives having a bridgehead alkoxy group is described involving Wolff rearrangement of α-diazo ketone in a bicyclo[2.2.2]octane derivative.