Some chemical transformations of 5-(propyn-2-yl)bicyclo[2.2.1]-2-heptene

Conclusions The Grignard reagent, obtained from 5-(propyn-2-yl)bicyclo[2.2.1]-2-heptene, reacts easily with Ac₂O, Et₂SiCl₂, Me₃SiCl, and acrolein to give in high yields [2.2.1]bicyclo-2-heptene derivativesthat contain in the side chain either an acetyl, diethylsilyl, trimethylsilyl, or a hydroxypropen-1-yl group. The Mannich reaction was also run with 5-(propyn-2-yl)bicyclo[2.2.1]-2-heptene.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2586–2589, November, 1982.     

Cyclodimerization of bicyclo[2.2.1]hepta-2,5-diene in the presence of rhodium-containing zeolite catalysts

It has been shown that norbornadiene is dimerized in the presence of rhodium-containing zeolite catalysts, forming hexacyclic [4+2]dimers preferentially. The effect of the structure and the method of preparation and pretreatment of the catalysts on their activity and selectivity in norbornadiene cycloaddition was studied. The influence of the above parameters on the change in the electronic state of rhodium in the course of the reaction was also investigated.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1913–1919, November, 1994.     

One-pot palladium-catalyzed synthesis of 2,3-disubstituted bicyclo[2.2.1]heptanes and bicyclo[2.2.1]hept-5-enes

A new and highly stereoselective palladium-catalyzed synthesis is reported, based on two subsequent insertions of the bicyclo[2.2.1]heptene system into an aryl or vinylpalladium bond, formed in situ from aryl or vinyl bromides.     

Microwave spectra and dipole moments of bicyclo [2.2.1]-hepta-7-one and bicyclo [2.2.1]hept-2-en-7-one

The microwave spectra of bicycle [2.2.1] hepta-7-one (I), bicyelo [2.2.1] hept-2-en-7-one (II), and exo-5,6-bisdeuteriobicyclo [2.2.1] hept-2-en-7-one (III) have been recorded in the region between 26.5 and 40.0 GHz. The rotational constants in the order A, B, C for the title compounds are 2773.24±0.31, 2301.74±0.04, and 2133.96±0.02 (I); 2979.22±0.08, 2418.60±0.01, and 2235.51±0.01 (II); and 2789.67±0.06, 2385.24±0.01, and 2150.60±0.01 (III). The rotational constants of four vibrationally excited states were also determined for (II). Quadratic Stark effect measurements on the 7₁₆ ← 6₁₅ transition of (I) gave ¦μ_a¦=2.99±0.03. Similar measurements on two 5 ← 4 and 4 ← 3 transitions of (II) gave ¦μ_a¦=2.88±0.03, ¦μ_b¦=0.39±0.03, ¦μ_c¦=0, and ¦μ_total¦=2.91±0.04.     

Intermediacy of bicyclo[2.2.1]hepteneone in the photolysis of bicyclo[2.2.2]octenediones

UV Irradiation of cyclohexane solution of bicyclo[2.2.2]octenediones led to facile extrusion of carbon monoxide to give substituted dihydrobiphenyls along with the dehydrogenated products. The inseparable mixtures on DDQ oxidation afforded the biphenyl derivatives. Isolation of an intermediate arising from the initial monodecarbonylation lends support to a proposed mechanistic rationalization.     

2-Chlorobicyclo[2.2.1]hept-5-ene-2-carboxamide and 2-chlorobicyclo[2.2.1]heptane-2-carboxamide as precursors of bicyclo[2.2.1]hept-5-en-2-one and bicyclo[2.2.1]heptan-2-one: resolution,absolute configuration and hydrogen-bonding properties

The absolute configuration of bicyclo[2.2.1]heptan-2-one has not been correlated with a crystal structure of a chemical precursor. The only chemical correlation available had an ambiguity, which could have reversed the assignment. Herein, we report the resolution of 2-chlorobicyclo[2.2.1]hept-5-en-2-exo-carboxamide on a cellulose triacetate column and the crystal structures of the enantiomerically pure and racemic α-chloroamide. We found the absolute configuration (1R,2R,4R) for the (+)-enantiomer of the α-chloroamide. This compound was converted to (+)-bicyclo[2.2.1]hept-5-ene-2-one by base hydrolysis, and the 5,6-unsaturated compounds converted to the saturated congeners. This is the first unambiguous experimental determination of the absolute configuration of bicyclo[2.2.1]heptan-2-one and of bicyclo[2.2.1]hept-5-ene-2-one. The three crystal structures of 2-chlorobicyclo[2.2.1]hept-5-en-2-exo-carboxamide reported herein reveal H-bonded dimers, with two distinct orientations of the bicyclic portion relative to the carboxamide dimer. In the racemic crystal, each dimer is composed of two enantiomers, and the bicyclic portions have their bridge carbon atom (C-7) on opposite sides of the H-bonded carboxamide dimer moiety. In the enantiomerically pure crystals, the major dimer had both C-7 atoms on the same side of the carboxamide dimer moiety while the minor dimer had the C-7 atoms on opposite sides. The dimers are present in solution, and can be easily monitored.     

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.     

Dimerization of bicyclo[2.2.1]hepta-2,5-diene in the presence of rhodium carboxylate complexes

Conclusions Bicyclo [2.2.1]hepta-2,5-diene (norborndiene) dimerizes in the presence of Rh (II) carboxylate complexes Rh₂(RCOO)₄ (R=CH₃, CF₃) at 25–100°C to form preferentially the products of (4+2) cycloaddition. The rate of the reaction in the presence of Rh₂ (CF₃COO)₄ is an order of magnitude higher than for Rh₂(CH₃COO)₄. Under the reaction conditions Rh(II) is reduced by norbornadiene to Rh(I).Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 635–639, March, 1982.     

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.     

Interconversion of bicyclo[2.2.1]hept-2-yne and 5-bicyclo[2.1.1]hexylidenecarbene

This work provides unambiguous results for the full equilibration of cycloalkyne 2 with its isomeric ring-contracted vinylidene 3 prior to their reaction with 2,3-dihydropyran (4), as evidenced by the products formed when 2 and 3 are produced directly from their precursors having bicyclo[2.2.1]heptyl and bicyclo[2.1.1]hexyl skeletons, respectively.     

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.     

Synthesis and Epoxidation of 5-(2-Aminoethyl)bicyclo[2.2.1]hept-2-ene Derivatives

A number of derivatives of 5-(2-aminoethyl)bicyclo[2.2.1]hept-2-ene (85-90% of the endo isomer) were synthesized by reactions with p-nitrobenzenesulfonyl chloride, p-toluenesulfonyl chloride, benzoyl chloride, p-nitrobenzoyl chloride, benzyl isocyanate, m-tolyl isocyanate, phenyl isothiocyanate, and endic anhydride. By reactions of the resulting sulfon- and carboxamides with peroxyphthalic acid generated in situ from phthalic anhydride and 40-45% hydrogen peroxide the corresponding epoxy derivatives were obtained. These reactions were not accompanied by heterocyclization into azabrendane derivatives, which is typical of homologous N-(p-nitrophenylsulfonyl)-endo-5-aminomethylbicyclo[2.2.1]hept-2-ene.     

Opening the [4 + 2 + 2] cycloadducts of bicyclo[2.2.1]hepta-2,5-dienes (norbornadienes) to cis-fused bicyclo[5.3.0]decanes

Tetracyclo[5.4.0.0.(2,4)0(3,7)]undec-9-enes, prepared by the transition-metal-catalyzed [4 + 2 + 2] homo-Diels-Alder reactions of norbornadiene and 1,3-butadienes, can be opened using either acid-promoted or Zeise's dimer-mediated cyclopropane ring cleavage, ultimately leading to cis-fused bicyclo[5.3.0]decanes (perhydroazulenes). Stereoselective functionalization of the olefin unit in the tetracycloundecenes to an alcohol or diol prior to ring opening is tolerated by the Zeise's dimer ([Pt(C(2)H(4))Cl(2)](2)) catalyst to yield highly functionalized bicyclo[5.3.0]decanes, which form the core structure of numerous sesquiterpenes.     

Homodimerization of spiro{bicyclo[2.2.1]Hepta-2,5-Diene-7,1′-cyclopropane}, catalyzed by group VIII transition metal complexes

Conclusions The homodimerization of spiro{bicyclo[2.2.1]hepta-2,5-diene-7,1-cyclopropane} (I) has been investigated in the presence of Ni-, Fe-, Co-, Rh-, and Ir-based metal complex catalysts. Depending on the nature of the metal and its ligand environment cyclodimerization of (I) can take place via [2+2]-, [2+2+2]-, and [4+4]-cycloaddition schemes, to give high yields of hepta-, octa-, and nonacyclic strained hydrocarbons.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2592–2599, November, 1988.     

Synthesis of bicyclo[2.2.1]heptyl monoethers of aliphatic diols

An effective procedure for the synthesis of bicyclic monoethers by etherification of bicyclo[2.2.1] heptane-exo-2-ol and its exo-5-methyl-substituted derivative by aliphatic diols in the presence of naphthalene-1,5-disulfonic acid as a catatlyst was developed.

     

Synthesis of halomethyl-substituted bicyclo[2.2.1]hept-2-yl(meth)acrylates

Russian Journal of Applied Chemistry - Bicyclic esters, which are reactive monomers for the synthesis of new polymeric products and also of organic compounds, were synthesized by the reaction of...     

Transition metal-catalyzed [4 + 2 + 2] cycloadditions of bicyclo[2.2.1]hepta-2,5-dienes (norbornadienes) and bicyclo[2.2.2]octa-2,5-dienes

The transition-metal-catalyzed [4 + 2 + 2] cycloadditions of norbornadienes, bicyclo[2.2.2]octa-2,5-diene, and benzobarrelene with 1,3-butadienes proceed in excellent yields using cobalt-based catalytic systems. Two key distinctions between these [4 + 2 + 2] cycloadditions and the corresponding transition-metal-catalyzed [2 + 2 +2] reactions of norbornadiene are the requirement of a bimetal catalytic system with a bisphosphine ligand for the former and exclusive regioselectivity in the [4 + 2 + 2] reaction of 2-substituted norbornadienes to produce 1-substituted adducts. These distinctions may indicate two distinct mechanisms for the [4 + 2 + 2] and [2 + 2 + 2] reactions.