The Photolysis of Tricyclo[4.2.1.02,5]nonadiene: Support of a Doughert ‘type N’ mechanism from photoelectron spectroscopical studies

In earlier work on the photolysis of derivatives of tricyclo[4.2.1.0^2,5]nonadiene (I), the intermediacy of a biallyl-like structure has been postulated which is formed by C₁-C₂ bond cleavage of I in its first excited state. This mechanism is now supported by the results of photoelectron spectroscopical studies on I and its two dihydroderivatives. Further support is gained from the theoretically calculated Ehrenson C₁-C₂-bond indices for the ground and the first excited state of these molecules. While the results for I in principle can be rationalized on the (one-electron) basis of ‘through bond’ interaction between the two π-bonds, the absence of C₁-C₂ photocleavage for a substituted tricyclo[4.2.2.0^2,5]decadiene also requires consideration of an (all-electron) thermochemical driving force.     

Tricyclo [3.3.2.03,7]decan (9-Homo-nor-adamantan) Synthese und Umwandlungen

Tricyclo[3.3.2.0^3,7]decane (9-Homo-nor-adamantane). Synthesis and Transformations A synthesis of tricyclo [3.3.2.0^3,7]decane (=9-homo-nor-adamantane; 1 ), which belongs to the adamantaneland, a family of nineteen isomeric C₁₀H₁₆ hydrocarbons, is described, as well as derivatives thereof. Treatment of protoadamantan-5endo-ol (11) with either thionyl chloride or phosphorus pentachloride yielded under rearrangement the chloride 18 , and solvolysis of the 5endo-chloro-protoadamantane (16) led to the acetate 26, 18 and 26 having both the tricyclo [3.3.2.0^3,7]decane skeleton. Subsequent transformations gave the title compound 1 as well as the corresponding olefin 8 .     

The Adamantane Rearrangement of Tricyclo[4.2.2.01,5]decane to Tricyclo[5.3.0.04,8]decane

Regioselective generation of the C(2)-carbocation a of tricyclo[4.2.2.0^1,5]decane ( 1 ) by treatment of both corresponding epimeric alcohols 5 and 6 with BF₃ and trapping the rearranged tricyclo[5.3.0.0^4,8]decan-7-yl carbocation b with Et₃SiH as hydride-ion donor (ionic hydrogenation) gives the corresponding hydrocarbon 3 as sole product in almost quantitative yield. The latter is a known intermediate in the Lewis-acid-catalyzed rearrangement of 1 to adamantane ( 4 ).     

The Novel Adamantane Isomer Tricyclo[4.4.0.03,9]decane (2-Homotwistbrendane)

Two synthetic approaches to the novel C₁₀H₁₆ hydrocarbon tricyclo[4.4.0.0^3,9]decane ( 1 ; 2-homotwistbrendane), one of the 19 members of the adamantaneland, and its Lewis-acid-catalyzed rearrangement are described. One route starts from tricyclo[4.3.0.0^3,8]nonan-2-one ( 2 ; 2-twistbrendanone). The missing tenth C-atom is introduced by ring enlargement (Tiffeneau-Demjanov method). Starting from methyl 8,9,10-trinorborn-5-ene-2-endo-carboxylate ( 8 ), ring enlargement by one C-atom, regio- and stereoselective introduction of a C₁ unit to a 2-endo,6-endo-disubstituted bicyclo[3.2.1]octane, and ring closure by acyloin condensation are the key steps in the second approach.     

Tricyclo[7.3.1.02,7]tridecanes with an Amino Group at the Bridging Carbon. Synthesis and Stereochemistry

Hydroamination of tricyclo[7.3.1.02,7]tridec-2(7)-en-13-one according to Leukart reaction furnished (tricyclo[7.3.1.02,7]tridec-2(7)-en-13-yl)methanamides stereoisomeric at C¹³ atom. The corresponding epoxides were prepared therefrom. The unsaturated and epoxidized methanamides were hydrolyzed into amines that were converted into Schiff bases.The configurations of substances were established.     

Density functional study of tricyclo[3,3,1,13,7]decane and tricyclo[3,3,1,13,7]decsilane and their halogen derivatives

The B3LYP/3‐21G* ab initio molecular orbital method from the Gaussian 94 computer program package was applied to study tricyclo[3,3,1,1^3,7]decane and tricyclo[3,3,1,1^3,7]decsilane molecules and their halogen derivatives (1,3,5,7‐tetrahalotricyclo[3,3,1,1^3,7]decane and 1,3,5,7‐tetrahalotricyclo[3,3,1,1^3,7]decsilane, C₁₀H₁₂X₄, and Si₁₀H₁₂X₄). The optimized structures of these compounds were obtained. Ionization potentials, HOMO and LUMO energies, energy gaps, heats of formation, atomization energies, and vibration frequencies were calculated. These calculations indicate that these molecules are stable and have T_d symmetry. Tricyclo[3,3,1,1^3,7]decsilane and its halogen derivatives (Si₁₀H₁₂X₄) are found to have higher conductivity than that of tricyclo[3,3,1,1^3,7]decane and its halogen derivatives (C₁₀H₁₂X₄). 1,3,5,7‐Tetraflourotricyclo[3,3,1,1^3,7]decane (C₁₀H₁₂F₄) and 1,3,5,7‐tetraflourotricyclo[3,3,1,1^3,7]decsilane (Si₁₀H₁₂F₄) were found to be the easiest compounds to form and the most difficult to dissociate of all 1,3,5,7‐tetrahalotricyclo[3,3,1,1^3,7]decane and 1,3,5,7‐tetrahalotricyclo[3,3,1,1^3,7]decsilane compounds, respectively. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 72: 189–198, 1999     

The Novel Adamantane Isomer 2,5-Trimethylenenorbornane (Tricycio-[5.3.0.3,9]decane, 4-Homotwistbrendane)

A synthesis of the novel C₁₀H₁₆ hydrocarbon 2,5-trimethylenenorbornane (tricyclo[5.3.0.0^3,9]decane, 1 ), one of the 19 members of the ‘adamantaneland’, and its Lewis-acid-catalyzed rearrangement is described.     

Synthese von Tricyclo[4.4.1.13, 8]dodecan-4, 9-dion und Tricyclo[4.4.1.13, 8]dodeca-4, 9-dien

Treatment of 2, 6-bis-aminomethyladamantane-2, 6-diol (II) with nitrous acid gives tricyclo[4.4.1.1^{3, 8}]dodecane-4, 9-dione (III), which is converted into the tricyclo[4.4.1.1^{3, 8}]dodeca-4, 9-diene (V) by reduction to the corresponding diols (IV, R = H) and pyrolysis of their O-4-methylphenyl thiocarbonate O-esters. II is accessible from 2, 6-adamantanedione by reaction with diethyl aluminium cyanide and subsequent reduction with lithiumaluminium hydride. The physical properties of the new compounds including ¹³C NMR. spectra of III, V and tricyclo-[4.4.1.1^{3, 8}]dodecane are given.     

Synthesen von Tricyclo [5.2.1.04,8]decan (2-Homobrendan)

Syntheses of Tricyclo [5.2.1.0^4,8]decane (2-Homobrendane) Three different approaches to tricyclo [5.2.1.0^4,8] decane (5) (and derivatives thereof), one of the 19 isomeric hydrocarbons of the ‘adamantaneland’, are described: (1) Cyclization of properly functionalized bicyclo [3.2.1]octanes as 32 (cyclialkylation), 40+42 (thermocyclization) and 44+45 (photocyclization); (2) Silver-(I)-ion catalyzed rearrangement of 5,7- and 5,10-Dehydroprotoadamantane ( 63 and 64 , respectively) yielding tricyclo[5.2.1.0^4,8]dec-2- (39) and -5-ene (59) , respectively; (3) Thermal eliminative rearrangement of the 10endo-p-toluenesulfonate and -methanesulfonate of protoadamantane ( 71 and 72 ) and protoadamant-4-ene ( 76 and 77 ), respectively, yielding tricyclo [5.2.1.0^4,8]dec-2-ene (39) and -2, 5-diene (15) , respectively.     

Asymmetric ruthenium‐catalysed [2+2] cycloadditions between bicyclic alkenes and chiral aryl‐substituted acetylenic acyl camphorsultam alkynes

The regio‐ and absolute stereochemistry of (7S)‐N‐[4‐(3‐thienyl)tricyclo[4.2.1.0^2,5]non‐3‐en‐3‐ylcarbonyl]‐2,10‐camphorsultam tetrahydrofuran hemisolvate, C₂₄H₂₉NO₃S₂·0.5C₄H₈O, and (7S)‐N‐[4‐(4‐tolyl)tricyclo[4.2.1.0^2,5]non‐3‐en‐3‐ylcarbonyl]‐2,10‐camphorsultam, C₂₇H₃₃NO₃S, have been established. One contains a half‐occupancy tetrahydrofuran solvent molecule located on a twofold axis and the other contains two crystallographically unique molecules which are nearly identical. The extended structures of both complexes can be explained via weak C—H...O interactions, which link the molecules together into two‐dimensional sheets in the ab plane for the thienyl complex and ultimately into a three‐dimensional structure for the tolyl derivative. The stereochemistry of both structures confirms that [2+2] cycloadditions of bicyclic alkenes and alkynes catalysed by ruthenium are exclusively exo.     

13C NMR spectra of tricyclo[4.2.1.02,5]nonanes and tetracyclo[5.4.1.02,6.08,11]dodecanes

The ¹³C NMR spectra of tricyclo[4.2.1.0^2,5]nonanes and tetracyclo[5.4.1.0^2,6.0^8,11]dodecanes and their dimethyl derivatives were measured to demonstrate the four-membered ring annelation effects on the bicyclo[2.2.1]heptane skeleton, and the steric δ-syn effects of the methyl groups attached to the four-membered ring on the bridge carbons in these systems.     

Nitrochlorination of methyl tricyclo[4.1.0.02,7]heptane-1-carboxylate and phenyl tricyclo[4.1.0.02,7]hept-1-yl sulfone

Treatment of methyl tricyclo[4.1.0.0^2,7]heptane-1-carboxylate and phenyl tricyclo[4.1.0.0^2,7]hept-1-yl sulfone with a ～1:8 mixture of N₂O₄ and NOCl in diethyl ether at ?5 to 0°C gave products of formal anti-addition of NO₂Cl at the central C¹-C⁷ bond. In the reaction with phenyl tricyclo[4.1.0.0^2,7]hept-1-yl sulfone nitryl chloride acts as an effective chlorinating agent; as a result, a mixture of diastereoisomeric syn- and anti-6,7-dichlorobicyclo[3.1.1]hept-6-yl phenyl sulfones at a ratio of 7.5:1 is formed.     

The configuration and conformation of the tricyclo[4.4.1.12,5]dodecan-11-ols determined by 1H NMR spectroscopy using the shift reagent Eu(fod)3

The isomeric tricyclo[4.4.1.1^2,5]dodecan-11-ols have been synthesized from the (6+4) cycloaddition product of tropone with cyclopentadiene. The configuration and conformation of each isomer was determined from the proton shift gradients induced in the olefinic proton signals in the ¹H NMR spectra of intermediate compounds by Eu(fod)₃.     

Reactions of sulfur halides with unsaturated compounds. 26. Reactions of sulfur dichloride with tricyclo[4.2.2.02,5]deca-3,7-dienes and tricyclo[4.2.2.02,5]deca-3,7,9-trienes. Synthesis of compounds with a novel thiaskeletal structure

Addition of sulfur dichloride to tricyclo[4.2.2.0^{2, 5}]deca-3,7-dienes and tricyclo[4.2.2.0^2,5] deca-3,7,9-trienes is accompanied by intramolecular cyclization to give high yields of adducts with the novel thiaskeletal 7-thiatetracyclo[4.2.2.0^4,8.0^5,10]undecane structure. In the reaction of SCl₂ with the 2,3-endo, endo-diester (V), intramolecular cyclization is accompanied by lactonization, to give quantitative yields of the thiaskeletal chlorolactone (X). The structure of the latter compounds was established by x-ray diffraction examination.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 858–864, April, 1990.For previous commmunication see [1].     

Alkylations of tricyclo[5.2.1.0]deca-4,8-dien-3-one by a cuprate reaction

Alkylation at C₆ of tricyclo[5.2.1.0^2,6]deca-4,8-dien-3-one (R=H) was achieved by treatment of 6-bromotricyclo[5.2.1.0^2,6]deca-4,8-dien-3-one with lithium dimethylcuprate and subsequently with an appropriate electrophile. The best results were obtained in THF as the solvent. A wide range of alkyl halides, bromo ketones and esters, and acetyl chloride resulted in C₆-tricyclo[5.2.1.0^2,6]deca-4,8-dien-3-ones in moderate to good yields. This alkylation reaction proceeds via a C₆-carbanionic Cu intermediate, which is likely stabilized by the enone olefinic bond. 6-Bromo-endo-tricyclo[5.2.1.0^2,6]dec-8-en-3-one, which lacks this double bond, behaves differently. Treatment with lithium dimethylcuprate leads to dehydrobromination to give tricyclo[5.2.1.0^2,6]deca-2(6),8-dien-3-one in high yield.     

Apparent Failure of the Wharton Rearrangement in a Tricyclo[7.1.1.02,7]undecane

The Wharton rearrangement of 2,3-epoxytricyclo[7.1.1.0^2,7]undecan-3-one, a sterically hindered system, which should have led to an allyl alcohol with the OH group at a bridgehead, gave instead the allylically rearranged alcohol. The desired hydroxy compound was prepared by the Barton modification of the Wharton rearrangement: borohydride reduction to the epoxy alcohols, reaction with N, N′-thiocarbonylbisimidazole, and treatment with Bu₃SnH. The bridgehead alcohol (and other 2-oxygenated tricyclo[7.1.1.0^2,7]undecanes) readily rearranged under acidic or thermal conditions.     

Quantum chemical study of the structure of bicyclo[2.2.0]hex-1(4)-ene and its dimers

The RHF, B3LYP, and PBE0/6-311G** quantum chemical methods are used to determine the point symmetry group and the equilibrium structure of bicyclo[2.2.0]hex-1(4)-ene (I, D _2h ), its two stable dimers (tricyclo[4.2.2.2^2,5]dodeca-1.5-diene (II, D _2h ) and 2,5-dimethylenetricyclo[4.2.2.0^1,6]decane (III, C ₂)), and pentacyclo [4.2.2.2^2,5]dodecane (IV, D ₂) that is a hypothetical intermediate in the dimerization reaction of the molecules of I. The relation of total energies is obtained with regard to zero-point vibrations: E(III) < E(II) ≪ E(IV) ≪ 2E(I).     

The Synthesis of 5,6-Disubstituted Bicyclo[2.1.1]hexenes and 3,5-Disubstituted Tricyclo[2.2.0.02,6]hexanes

There are relatively few methods for synthesizing bicyclo[2.1.1]-hexenes and tricyclo[2.2.0.0^2,6]hexanes.¹ However, now that benzvalene (I), the highly strained structural isomer of benzene has become a readily available compound,² it is possible to prepare disubstituted compounds like II and III in a straightforward fashion.     

Photochemische Umwandlungen. XV [1] Photochemische Isomerisierung des exo-Tricyclo[4.2.1.02′5]nona-3,7-dien-Systems. Vorläufige Mitteilung

The acetone sensitized isomerization of two exo-tricyclo[4.2.1.0^2,5]nonadiene derivatives, of the corresponding tricyclo[4.3.0.0^2,5]nonadienes, and the photoisomerization of two bicyclo[4.3.0]nonatrienes by direct excitation are described.     

Zur Photochemie von (Z,Z)-2,7-Cyclodecadien-1-on und 4,8-Cyclododecadien-1-on. Synthese und Eigenschaften von Tricyclo[5.3.0.02,8]decan-Systemen

On the Photochemistry of (Z,Z)-2,7-Cyclodecadien-1-one and 4,8-Cyclododecadien-1-one. Synthesis and Properties of Tricyclo[5.3.0.0^2,8]decane Systems Irradiation of (Z,Z)-2,7-cyclodecadien-1-one ( 3 ) yields (Z,Z)-3,7-cyclodecadien-1-one ( 12 ) or tricyclo-[5.3.0.0^2,8]decan-4-one ( 16 ), depending on the reaction conditions. Irradiation of 4,8-cyclododecadien-1-one ( 28 ) results also in a light-induced transannular [2 + 2] cycloaddition, yielding tetracyclo[7.3.0.0^2,100^3,6]dodecan-1-one ( 30 ). Starting from 16 , the preparation of tricyclo[5.3.0.0^2,8]dec-4-ene ( 19 ), tricyclo[5.3.0.0^2,8]dec-4-ene ( 21 ) and tricyclo[5.3.0.0^2,8]deca-3,5-diene ( 24 ) is described. The ¹H-NMR and ¹³C? NMR spectra of the newly prepared compounds are discussed. In the case of 19, 21 , and 24 , the electronic structure is discussed on hand of their PE spectra.