Carbon-13 chemical shifts of bicyclo[3.2.1]octane and bicyclo[2.2.1]heptane derivatives

¹³C chemical shifts of more than fifty bicyclo[3.2.1]octane and bicyclo[2.2.1]heptane derivatives (hydrocarbons, alcohols, ketones and esters) have been determined. The usefulness of ethyl derivatives for the assignment of close ¹³C chemical shifts in bicyclic methyl derivatives is shown both for the bicyclo[3.2.1]octane and bicyclo[2.2.1]heptane series. Comparison of substituent effects on α-, β-, γ- and δ-carbons in both series of compounds shows remarkable differences in steric interactions. In contrast to the rigid bicyclo[2.2.1]heptane system, both chair and boat conformations can be predominant in the bicyclo[3.2.1]octane series with the conformationally flexible 6-membered ring.     

The electronic structure of bicyclo [2.2.1] heptane and of bicyclo [2.2.2] octane

An ab initia SCF-LCAO-MO study of bicyclo [2.2.1] heptane(I) and of bicyclo [2.2.2] octane(II) has been performed. The electronic structure and the nature of the molecular orbitals and of the bonds have been analyzed. Interactions between fragment orbitals may be recognized. The bridgehead C-H bonds interact dominantly “through-space” in I and “through-bond” in II. Some relations between electronic structure and molecular properties are discussed.     

Thermodynamic parameters of adsorption of adamantane and its derivatives on graphitized thermal carbon black

The adsorption equilibrium constants for adamantane, 1-fluoro-, 1-chloro-, 1,3-difluoro-, 1,3-dichloro-, 1,3-dibromo-, and 1-hydroxyadamantane, and methyl 1-adamantyl ketone were determined by gas chromatography. The results were compared with molecular statistical calculations based on the known atomic-atomic potentials of the interaction of atoms of the sorbate molecule with the C atom of graphitized thermal carbon black (GTCB). The experimental adsorption heats exceed the calculated values by 3-10 kJ mol^-1. The reasons for this divergence are discussed. The changes in the adsorption entropy show that the molecules of the studied compounds form a layer of the ideal dimeric gas on the GTCB surface upon adsorption.     

Biohydroxylation d'un aza-2 bicyclo [2.2.1] heptane

Biohydroxylation with Beauveria sulfurescens of the 5-exo position of the 2-aza bicyclo [2.2.1] heptane ring system gives rise to a precursor of carbocyclic 2-deoxy nucleosides.     

Experimental and molecular statistical study of alkyladamantane adsorption on graphitized thermal carbon black

Experimental measurements and molecular statistics methods were used to calculate thermodynamic characteristics of adsorption (TCA) of alkyladamantanes of different structure on the surface of hydrogen-treated graphitized thermal carbon black (GTCB) Carbopack C HT. High selectivity of separation of isomeric alkyladamantanes on GTCB is due to specific features of their geometry and electronic structure. The influence of the spatial structure of adsorbates on the TCA was established. Special attention was given to analysis of the heat capacities of adsorption. The best agreement between the experimental TCA and those calculated by the molecular statistics methods is achieved when the “cage effect“ in the adamantane ring is taken into account. The corresponding corrections are introduced into the parameters of the atom-atomic potential function of pair intermolecular interaction of the Me groups with the carbon atoms of the basal face of graphite, which are localized in the nodal positions of the lattice. The critical parameters for a large group of alkyladamantanes were calculated in terms of the additive group Lydersen method. A set of various topological indices used further for constructing structure-retention correlations on GTCB was obtained.     

Conversion of bicyclo[2.1.0]pentane into 2,3-dioxabicyclo[2.2.1]heptane via t-butyl peroxymercuriation

Bicyclo[2.1.0]pentane has been converted in 45% yield into 2,3-dioxabicyclo-[2.2.1]heptane by the sequence t-butyl peroxymercuriation, iododemercuriation, epimerisation of the resultant 1-t-butylperoxy-3-iodocyclopentane, and reaction of the trans isomer with silver trifluoroacetate.     

Gas chromatographic investigation of adsorption equilibria on graphitized thermal carbon black

Summary Retention volumes and heats of adsorption at low surface coverages of graphitized thermal carbon black (GTCB) for C₆–C₁₄ aromatic hydrocarbons have been determined. The dependence of heats of adsorption of these molecules on their structure and the number of carbon atoms in the molecule have been investigated. Substitution in the ring in methylbenzenes is not equivalent to the lengthening of the side-chain in the isomers of n-alkylbenzenes and gives rise to a much greater increase in the retention volumes and heats of adsorption.     

7-Selenabicyclo[2.2.1]heptane

Thermolysis of a benzene solution of N-[4-(p-(methoxybenzyl)seleno)cyclohexanoyl]-N,S-dimethyldithiocarbonate affords the hitherto unknown 7-selenabicyclo[2.2.1]heptane in 48% conversion and in 20% yield after chromatography. G3(MP2)-RAD calculations predict a rate constant of 5 × 10(4) s(-1) at 80 °C (3.8 × 10(6) s(-1) at 200 °C) for the intramolecular homolytic substitution process involved in this cyclization.     

The cell effect in adamantane adsorption on graphitized thermal carbon black

Nonequivalence of the nodal and bridging carbon atoms of the adamantane molecule during adsorption on graphitized thermal carbon black was shown. The nonequivalence is related to a special type of intermolecular interaction, the cell effect. Based on the experimental data and the molecular statistical calculations of Henry's constants, the parameters of atomatom potentials for the nodal carbon atoms in the adamantane molecule were found. This atom-atom potential differs from that known for the carbon atom in the sp³-hybridization. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 849–853, May, 2000.     

Reactions of bicyclo[4,1,0]heptane derivatives with phosphorus pentachloride

Russian Journal of General Chemistry -     

Enantioselective microbial hydroxylation of bicyclo(2.2.1)heptane carbon skeleton

Bicyclo(2.2.1)heptane-7-carboxylic acid ($\text{9}$) and methyl bicyclo(2.2.1)hept-2-ene-7-$\text{syn}$-carboxylate ($\text{5}$) were microbiologically hydroxylated to give (1$\text{R}$)-2-hydroxy derivatives.     

Thermodynamic parameters of adsorption of isomeric chloronaphthalenes on graphitized thermal carbon black

Henry's constants and the heats of adsorption of isomeric chloronaphthalenes on graphitized thermal carbon black were calculated by the semiempirical molecular statistical method. The calculated data were compared with experimental results. The best agreement was achieved when corrections for the interaction of the Cl atom with the C atom of the adjacent benzene ring and the presence of other Cl atoms inortho-positions are introduced in calculations of the atom-atomic potential. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 8, pp. 1484–1489, August, 1999.     

Ketones of the bicyclo[2.2.1]heptane series in the synthesis of geminal diamides

The transformations of isofenchone and of 5-exo-ethylnorcamphor under the conditions of the Ritter reaction have been studied. These ketones undergo transformations similar to those that have been described for their structural analogues camphor and isocamphanone, as a result of which the corresponding geminal diamides are formed. The structures of the compounds synthesized were shown by IR, mass, and¹H NMR spectroscopies.Institute of Physical Organic Chemistry, Belorussian Academy of Sciences. Translated from Khimiya Prirodnykh Soedinenii, No. 2, pp. 208–209, March–April, 1992.     

Molecular statistical calculations of the adsorption of proline and its hydroxy derivatives on graphitized thermal carbon black

The thermodynamic characteristics of adsorption of proline and its hydroxy derivatives on the surface of graphitized thermal carbon black (GTCB) were calculated. The arrangement of hydroxyl groups in the amino acid molecule was shown to influence their adsorption on GTCB. The influence of internal rotation angles in proline and its hydroxy derivative molecules on their adsorption on GTCB was studied.     

Enzymatic preparation of optically active 7-oxabicyclo[2.2.1] heptane derivatives

Enzymatic resolution of endo-7-oxabicyclo [2.2.1] hept-2-yl butyrates 3 and 5 using lipase from Candida cylindracea led to optically pure bicyclic alcohols and esters being important intermediates for the synthesis of biologically active compounds.     

Unusual reactivity of bicyclo[2.2.1]heptene derivatives during the ozonolysis

This paper describes mechanistic studies on the ozonolysis of bicyclo[2.2.1]heptene derivatives 6 and 7 obtained from (R)-(+)-pulegone through the cyclopentadiene 5 and its Diels-Alder reaction with maleic anhydride. The ozonolysis of the tricyclic diol 7 led to the ketone 8 with the same skeleton while the anhydride 6 gave rise to the epoxide 10 and the bis-lactone 11. The structure of 8, 10 and 11 are confirmed by X-ray analysis. These unexpected results are discussed in terms of a π complex between ozone and the double bond.