Chemical synthesis with metal Atoms. Cyclodimerization of norbornadiene via nickela-cyclopentane intermediates.

The catalytic cyclodimerization of norbornadiene by reaction with nickel atoms has been re-investigated. Nickela-cyclopentane derivatives are formed in the presence of α,α′-dipyridyl, α,α′-dipyridyl-exo-trans-endo-3-nickela-pentacyclo[9.2.1.1^5,8 0^2,10.0^4,9]-pentadeca-6,12-diene being the major component. By contrast, the catalytic dimerization leads predominantly to the exo-trans-exo isomer of pentacyclo[8.2.1.1^4,7.0^2,9.0^3,8] tetradeca-5,11-diene. A norbornadiene cyclotrimer of exo-trans-exo-trans-exo structure is subsequently formed.     

Convenient new synthesis of snoutene [1] utilizing a dipolar cycloaddition of 4-phenyl-1,2,4-triazolin-3,5-dione

4-Phenyl-1,2,4-triazolin-3,5-dione readily cycloadds to Nenitzescu's hydrocarbon $\text{1}$^[6] with skeletal rearrangement. The major adduct $\text{6}$ can conveniently be transformed to the azo compound $\text{8}$, which upon photolysis or thermolysis yields up to 80 % pentacyclo[3.3.2.0^2,4,.0^3,7.o^6,8]dec-9-ene (“ snoutene ”).     

Electron transfer from highly strained polycyclic molecules

The details of electron transfer from strained, saturated hydrocarbons in electrochemical oxidations on platinum have been studied. Among the systems investigated were tetracyclo[3.2.0.0^2,7.0^4,6]heptane, tricyclo [4.1.0.0^2,7]heptane, pentacyclo[4.3.0.0^2,4.0^5,7]nonane, pentacyclo[4.4.0.0^2,5.0^3.8.0^4,7] decane, pentacyclo[4.2.0.0^2,5.0^3,8.0^4,7]octane, pentacyclo[4.3.0.0^2,5.0^3,8.0^4,7]nonane, bicyclo[2.1.0]pentane, and a variety of bicyclo[1.1.0]butane derivatives. The oxidation of 1,2,3-trimethylbicyclo [1.1.0]butane is discussed in detail.     

General approach for the synthesis of polyquinanes

The diborane-mediated reduction of labile β-diketones 4, 5 and 6 has been employed as the key step in the synthesis of the three polyquinanes, all-$\text{cis}$-tetracyclo-[6.6.0.0^1,5.0^8,12]tetradecane 1, all-$\text{cis}$-tricyclo[6.3.0.0^1,5]undecane 2 and all-$\text{cis}$-tetracyclo-[5.5.1.0^4,13.O^10,13]tridecane, staurane 3, respectively.     

Selective reductive dimerization of homocubane series oximes

The mixture of di- and monoethylene ketals obtained by the reaction of 1,9-dibromopentacyc lo[5.4.0.0^2,6.0^3,10.0^5,9]-undeca-8,11-dione followed by hydrolysis and ring contraction by Faworsky method was converted into a mixture of ethylene ketals of 7-bromopentacyclo[5.3.0.0^2,5.0^3,9.0^4,8]decan-6-one-4- and 5-bromopentacyclo[5.3.0.0^2,5.0^3,9.0^4,8]decan-6-one-8-carboxylic acid where the carboxy group was replaced by bromine along the procedure of Hunsdiecker-Borodine-Cristol. 6-Ethylene ketal of the pentacyclo[5.3.0.0^2,5.0^3,9.0^4,8] decan-6-one obtained by the debromination of ethylene ketals of 4,7- and 5,8-dibromopentacyclo[5.3.0.0^2,5.0^3,9.0^4,8] decan-6-one was hydrolyzed to ketone whose oxime was selectively reduced on a platinum catalyst into the di-6-pentacyclo[5.3.0.0^2,5.0^3,9.0^4,8]decylamine. The reaction of reductive dimerization was also characteristic of pentacyclo[4.3.0.0^2,5.0^3,8.0^4,7]-nonan-9-one and pentacyclo[6.3.0.0^2,6.0^3,10.0^5,9]undecan-4-one oximes, whereas the composition of the reduction products of pentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecan-8-one oxime depended on the amount of the catalyst.     

Diels–Alder reactivity of 2-(bromomethyl)-1,4-quinone and 2-bromo-5-(bromomethyl)-1,4-quinone with cyclopentadiene and the synthesis of new substituted pentacyclic systems

Photochemical synthesis of the novel compounds 3-bromotetracyclo [5.3.1.0^2,6.0^4,8] undec-10(12)-ene-9,11-dione, 1-(bromomethyl)pentacyclo [5.4.0.0^2,6.0^3,10.0^5,9]undeca-8,11-dione and 1-bromo-9-(bromomethyl)pentacyclo [5.4.0.0^2,6.0^3,10.0^5,9]undeca-8,11-dione is described.     

Synthesis of (4.5.5.5]fenestrane and a [4.4.5.5]fenestrane derivative

The synthesis of tetracyclo[5.4.1.0^4,12.0^9.12]dodecan-6-one $\text{12}$ via an intramolelecular photocycloaddition, its reduction to the hydrocarbon $\text{13}$ and its ring-contraction to tetracyclo-[4.4.1.0^3,11.0^9,11]undecane derivative $\text{16}$ is described.     

Transition metal complexes with cage-opened diamondoid tetracyclo[7.3.1.14,12.02,7]tetradeca-6.11-diene

Cage-opened diamondoid tetracyclo[7.3.1.1^4,12.0^2,7]tetradeca-6,11-diene forms complexes with AgNO₃ and CuCl. The latter crystallized from acetonitrile in polymeric form [Cu₂Cl₂(CH₃CN)(diene)]_n; in the presence of 2,2′-bipyridine, a double-charged monomeric Cu(I)-complex [Cu₂(bipy)₂(diene)]²⁺ formed. Both complexes were structurally characterized through X-ray crystal diffraction analysis.     

Some reactions of 1,2,3,4,7,7-hexafluorobicyclo[2,2,1]hepta-2,5-diene: Thermolysis and attack by methoxide ion and by bistrifluoromethyl nitroxide

1,2,3,4,7,7-Hexafluorobicyclo[2,2,1]hepta-2,5-diene gave 1,2,3,4-tetrafluorebenzene in at least 73% yield when heated to 450°C in a sealed tube; the CF₂ bridge appeared, in part, as octafluorocyclobutane. Nucleophilic attack by sodium methoxide- methanol on the diene occurred exclusively at the CFCF bond, causing the formation of 1,2,4,7,7-pentafluoro-3-methoxybicyclo- [2,2,1]hepta-2,5-diene and a 1,4,5,6,7,7-hexafluoro-5-methoxybicyclo [2,2,1]hept-2-ene thought, on the basis of ¹⁹F nmr data, to be the 6-$\text{endo}$-F,5-$\text{exo}$-MeO isomer. Radical attack on 1,2,3,- 4,7,7-hexafluorobicyclo[2,2,1]hepta-2,5-diene by bistrifluoromethyl nitroxide took place at both olefinic sites, with a $\text{ca}$. 10:1 preference for the CFCF linkage; all three geometrical isomers of 5,6-bis(bistrifluoromethylamino-oxy)-1,4,5,6,7,7- hexafluorobicyclo[2,2,1]hept-2-ene were formed.     

Thionation of the monoacetal of pentacyclo[5.4.0.0.0.0]undecane-8,11-dione

As part of a programme to synthesize thione derivatives with pentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecane moieties it was decided to sulfurize the monoacetal 6 of pentacyclo[5.4.0.0^2,6.0^3,10.0^5,9]undecane-8,11-dione 2. Unexpectedly the diol 9 was isolated as the product.     

Novel skeletal rearrangement in addition reaction to tricyclo[4,2,2,02,5]deca-3,7-diene system

The “doping-addition” of RSCl to the tricyclo[4,2,2,0^2,5]deca-3,7-diene derivatives which are incapable of lactone ring closure proceeds to give the novel type of rearranged product, $\text{7}$, due to the two subsequent 1,2-shifts.     

Synthesis of a tetracyclodecenone with two orthogonal π-electron systems via a 1,3-through cage elimination in a bridgehead substituted 1,3-bishomocubyl acetate

Stereoselective reduction of 1,3-bishomocubanone acetate $\text{1}$ followed by mesylation leads to an epimeric mixture of mesylates $\text{3}$. Base induced homoketonization of the anti-epimer $\text{3b}$ affords tetracyclo[5.3.0.0^2,5 O^4,8]decenone $\text{4}$.     

Exo/emdo soltolysis rate ratios in constrained 2-norbornyl systems

Tetracyclol[6.2.1.0^2,6.0^5,10]undec-3-yl derivatives ($\text{6}$ - $\text{8}$) show typically high tertiary exo/endo solvolysis rate ratios, but the ratios for secondary reactants are suppressed. The rate and product data support the theory of anchimeric assistance in the parent $\text{exo}$-2-norbornyl solvolysis.     

General approach for the synthesis of polyquinanes: stereospecific,regiospecific entry into the tetracyclo-[6.6.0.01,5.08,12]tetradecane system

The synthesis of tetracyclo-[6.6.0.0^1,5.0^8,12]tetradecane-4,6,11,13-tetraone $\text{12}$ is described.     

Synthesis of diamantane via skeletal isomerization of hydrogenated cyclohepta-1,3,5-triene dimers in ionic liquid [Et<Subscript>3</Subscript>NH]<Superscript>+</Superscript> [Al<Subscript>2</Subscript>Cl<Subscript>7</Subscript>]<Superscript>–</Superscript>

Diamantane was synthesized in 91–97% yield by skeletal isomerization of a mixture of hydrogenated cyclohepta-1,3,5-triene dimers, pentacyclo[8.4.0.0^3,7.0^4,14.0^6,11]tetradecane and pentacyclo-[7.5.0.0^2,8.0^5,14.0^7,11]tetradecane, at a ratio of 3: 2 in the presence of ionic liquid [Et₃NH]⁺ [Al₂Cl₇]^–.     

Valence isomerization of C9H10hydrocarbons: Photochemical reactions of bicyclo [3.2.2] nona-2,6,8-triene and its dihydro-derivatives

The valence isomerization reaction of bicyclo[3.2.2]nona-2,6,8-triene ($\text{2}$), which photoisomerized to two homologues of semibullvalene, was discussed with the photoreactions of its dihydro-dreivatives, bicyclo[3.2.2]nona-6,8-diene ($\text{3}$) and bicyclo[3.2.2]nona-2,6-diene ($\text{4}$).     

Dehydro-anti-4,5,15,16-tetramethyl[22] (5,8) phenalenophane-1, 12-diene

A synthesis of $\text{anti}$-4,5,15,16-tetramethyl[2₂] (5,8) phenalenophane-1,12-diene ($\text{11}$) is described as well as its transformation via a radical abstraction process to an enantiomeric mixture of the Cope rearrangement product $\text{3}$.     

A simple synthesis of bis-annulated bicyclo[2.2.2]octenones containing a β,γ-enone chromophore and photochemical reactions: a new entry into angular tetraquinane and other polycyclic systems

Synthesis of endotetracyclo[5.5.2.0.^2,60^8,12]tetradeca-3(4),8(12)-dien-13-one from 5-indanol and photoreactions in singlet and triplet excited state leading to complex polycyclic systems is reported. Crystal structure of 14-spiroepoxyendotetracyclo[5.5.2.0.^2,60^8,12] tetradeca-3(4),8(12)-dien-13-one is also reported.     

Convenient preparative synthesis of pentacyclo[5.3.0.02,5.03,9.04,8]decane (<Emphasis Type="Italic">C</Emphasis><Subscript>2</Subscript>-Bishomocubane)

By reaction of pentacyclo[5.3.0.0^2,5.0^3,9.0^4,8]decane-6,10-dione 6-ethyleneketal with lithium aluminum hydride the corresponding hydroxyketal was obtained whose hydroxy group was replaced by chlorine at boiling in CCl₄ in the presence of a 15% molar excess of triphenylphosphine. 6-Ethyleneketal of pentacyclo-[5.3.0.0^2,5.0^3,9.0^4,8]decan-6-one obtained by dechlorination of the chloroketal in a system lithium-t-BuOH in THF was hydrolyzed to ketone by heating in 10% sulfuric acid in the presence of THF. The obtained ketone was reduced along Wolf-Kishner reaction to pentacyclo[5.3.0.0^2,5.0^3,9.0^4,8]decane.