A synthesis of the tricyclo[6.3.0.0]undecane system.

A short and efficient synthetic route to the tricyclo[6.3.0.0^2,6]undecane ring system is described; the key steps are photochemical annelation of an enolized β-diketone to produce a 1,5-diketone (the de Mayo reaction) followed by intramolecular reductive coupling using a low valence titanium species (McMurry's reagent).     

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     

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.     

Synthesis of tricyclo[6.2.2.0]dpdecane and tricyclo[6.3.1.0]dodecane ring systems involving intramolecular cyclisation of diazomethyl ketones

2,8-Dimethyltricyclo[6.2.2.0^1,6]dodeca-2,5-diene-4,9-dione ( ), 2,9-dimethyltricyclo [6.3.1.0^1,6]dodeca-2,5-diene-4,10-dione ( ) and 2-methyltricyclo[6.3.1.0^1,6]dodeca-2,5-diene-4,10-dione ( ) have been synthesised for entry into the ring systems of a few tetracyclic diterpenes.     

Acid-catalyzed rearrangements of tricyclo[4.3.2]Propellane derivatives

The acid-catalyzed rearrangements of three model tricyclo[4.3.2] propellane derivatives have been explored. In each case the observed products are proposed to arise via a concerted 1,2-shift of the cyclobutane bond having an antiperiplanar alignment with the leaving group (i.e., stereoelectronic control).     

Gas chromatographic behaviour of isomeric tricyclo[10.4.0.04,9]hexadecanes

Summary Using achiral stationary phases of different polarity in capillary gas chromatography it is demonstrated that the hydration of 1,2–5,6-dibenzocycloocta-1,5-diene yields five isomers of the tricyclo[10.4.0.0^4,9]hexadecanes. With highly polar stationary phases all isomers of the tricyclic hexadecanes and the semihydrated products in the mixture were also separated from each other. The chiral isomers were separated on cyclodextrin stationary phase. Moreover, with columns of achiral and chiral phases coupled in series, in a double oven gas chromatograph, it was possible to estimate the configuration of the isomers. The separation of diastereomers on chiral stationary phases is a useful means for structural assignment of isomeric compounds.Dedicated to Professor Leslie S. Ettre on the occasion of his 70th birthday.     

Reaction products of methyl tricyclo[4.1.0.02,7]heptane-1-carboxylate and tricyclo[4.1.0.02,7]hept-1-yl phenyl sulfone with dinitrogen tetraoxide

The reaction of methyl tricyclo[4.1.0.0^2,7]hepatne-1-carboxylate with dinitrogen tetraoxide in diethyl ether at ?10 to 0°C, followed by treatment of the reaction mixture with methanol, gave approximately equal amounts of methyl exo,syn-6,7-dinitro-and exo-6-hydroxy-syn-7-nitrobicyclo[3.1.1]heptane-endo-6-carboxylates. Tricyclo[4.1.0.0^2,7]hept-1-yl phenyl sulfone reacted with dinitrogen tetraoxide under analogous conditions to produce a mixture of diastereoisomeric exo,syn-and endo,syn-6,7-dinitro-6-phenylsulfonylbicyclo-[3.1.1]heptanes and 6,6-dimethoxy-endo-7-nitrobicyclo[3.1.1]heptane at a ratio of 4.5:2:1. Probable factors responsible for the different stereoselectivities in the addition of N₂O₄ at the central C¹-C⁷ bond of the initial tricycloheptane compounds were discussed. The structural parameters of the dinitro ester and related dinitro sulfone were compared on the basis of the X-ray diffraction data.     

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.     

Addition of dichlorocarbene to tricyclo[4.3.0.03,7]nona-4,8-diene

Addition of dichlorocarbene to tricyclo[4.3.0.0^3,7]nona-4,8-diene (brexadiene) under conditions of phase transfer catalysis occurs from theexo side. Cyclopropyl-allyl rearrangement of intermediate chlorocyclopropanes yields tricyclo[5.4.0.0^3,8]undecadienes. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1494–1497, August, 1997.     

Enzymic optical resolution and absolute configuration of tricyclo[5.2.1.02,6]decadienones

Access to optically active endo-tricyclodecadienones 1 (X=CH₂) has been realized by (i) classical resolution of the diastereomeric ephedrine salts of 3 and (ii) pig liver esterase catalyzed kinetic resolution of 2.