Preparation and Diels-Alder Reactivity of 2,3,5,6,7,8-Hexamethylidenebicyclo [2.2.2]octane (‘[2.2.2]Hericene’). Force-field calculations of exocyclic dienes as a moiety of bicyclic skeletons

The [2.2.2]hericene ( 6 ), a bicyclo[2.2.2]octane bearing three exocyclic s-cis-butadiene units has been prepared in eight steps from coumalic acid and maleic anhydride. The hexaene 6 adds successively three mol-equiv. of strong dienophiles such as ethylenetetracarbonitrile (TCE) and dimethyl acetylenedicarboxylate (DMAD) giving the corresponding monoadducts 17 and 20 (k₁), bis-adducts 18 and 21 (k₂) and tris-adducts 19 and 22 (k₃), respectively. The rate constant ratio k₁/k₂ is small as in the case of the cycloadditions of 2,3,5,6-tetramethylidene-bicyclo [2.2.2]octane ( 3 ) giving the corresponding monoadducts 23 and 27 (k₁) and bis-adducts 25 and 29 (k₂) with TCE and DMAD, respectively. Constrastingly, the rate constant ratio k₂/k₃ is relatively large as the rate constant ratio k₁/k₂ of the Diels-Alder additions for 5,6,7,8-tetramethylidenebicyclo [2.2.2]oct-2-ene ( 4 ) giving the corresponding monoadducts 24 and 28 (k₁) and bis-adducts 26 and 30 (k₂). The following second-order rate constants (toluene, 25°) and activation parameters were obtained for the TCE additions: 3 +TCE→ 23 : k₁ = 0.591±0.012 mol^?1·l·s^?1, ΔH^≠=10.6±0.4 kcal/mol, and ΔS^≠ = ?24.0±1.4 cal/mol·K (e.u.); 23 +TCE→ 25 : k₂=0.034±0.0010 mol^?1·l·s^?1, ΔH^≠ = 10.6±0.6 kcal/mol, and ΔS^≠ = ?29.7±2.0 e.u.; 4 +TCE→ 26 : k₁ = 0.172±0.035 mol^?1·l·s^?1, ΔH^≠ 11.3±0.8 kcal/mol, and ΔS^≠ = ?24.0±2.8 e.u.; 24 +TCE→ 26 : k₂ = (6.1±0.2)·10^?4 mol^?1·l·s^?1, ΔH^≠ = 13.0±0.3 kcal/mol, and ΔS^≠ = ?29.5±0.8 e.u.; 6 +TCE→ 17 : k₁ = 0.136±0.002 mol^?1·l·s^?1, ΔH^≠ = 11.3±0.2 kcal/mol, and ΔS^≠ = ?24.5±0.8 e.u.; 17 +TCE→ 18 : k₂ = 0.0156±0.0003 mol^?1·l·s^?1, ΔH^≠ = 10.9±0.5 kcal/mol, and ΔS^≠ = ?30.1 ± 1.5 e.u.; 18 +TCE→ 19 : k₃=(5±0.2) · 10^?5 mol^?1 mol^?1 ·l·s^?1, ΔH^≠ = 15±3 kcal/mol, and ΔS^≠ = ?28 ± 8 e.u. The following rate constants were evaluated for the DMAD additions (CD₂Cl₂, 30°): 6 +DMAD→ 20 : k₁ = (10±1)·10^?4 mol^?1 · l·s^?1; 20 +DMAD→ 21 : k₂ = (6.5±0.1) · 10^?4 mol^?1 ·l·^?1; 21 +DMAD→ 22 : k₃ = (1.0±0.1) · 10^?4 mol^?1 ·l·s^?1. The reactions giving the barrelene derivatives 19, 22, 26 and 30 are slower than those leading to adducts that are not barrelenes. The former are estimated less exothermic than the latter. It is proposed that the Diels-Alder reactivity of exocyclic s-cis-butadienes grafted onto bicycle [2.2.1]heptanes and bicyclo [2.2.2]octanes that are modified by remote substitution of the bicyclic skeletons can be affected by changes inthe exothermicity of the cycloadditions, in agreement with the Dimroth and Bell-Evans-Polanyi principle. Force-field calculations (MMPI 1) of 3, 4, 6 and related exocyclic s-cis-butadienes as a moiety of bicyclo [2.2.2]octane suggested single minimum energy hypersurfaces for these systems (eclipsed conformations, planar dienes). Their flexibility decreases with the degree of unsaturation of the bicyclic skeleton. The effect of an endocyclic double bond is larger than that of an exocyclic diene moiety.     

Synthesis of 1,4-diazabicyclo[2.2.2]octane

Double intramolecular cyclization of N,N-bis(2-chloroethyl)-N-N-bis(2-cyanoethyl)ethylenediamine leads to 1,4-bis(2-cyanoethyl)-1,4-diazoniabicyclo[2.2.2]octane dichloride, which undergoes decyanoethylation to 1,4-diazabicyclo[2.2.2]octane when it is heated. The structures of the compounds were confirmed by their IR and PMR spectra.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 548–550, April, 1978.     

Synthesis of bridgehead hydroxy bicyclo[2.2.2]octane derivatives

Two independent synthetic routes, starting from 1,3-cyclohexadione, toward the 4-hydroxy bicyclo[2.2.2]octane-2,6-dione derivative 3 are described.     

Thermal behaviour of some dibenzobicyclo[2.2.2]octane derivatives

A number of dibenzobicyclo[2.2.2]octane derivatives have been studied due to the interest of such compounds as ligands for coordination compounds with potential biological activity. Their thermal behaviour has been analyzed in order to find out more information about their fragmentation. A connection between the bridge substituents and the fragmentation process has been observed.     

Synthesis of novel spiro-cyclohexene bicyclo[2.2.2]octane derivatives

A methodology for the synthesis of novel spiro-cyclohexene bicyclo[2.2.2]octane derivatives, including Claisen rearrangement and ring-closing metathesis (RCM) as key synthetic steps, is described.     

Synthesis of 5,6-benzo-1,2-diazabicyclo [2.2.2]octane

5,6-Benzo-1,2-diazabicyclo[2.2.2]octane was synthesized by nitrosation of 1,2,3,4-tetrahydrocinchoninic acid, reduction of the 1-nitroso derivative to 1-amino-1,2,3,4-tetrahydrocinchoninic acid, cyclodehydration of it to 3-oxo-5,6-benzo-1,2-diazabycyclo[2.2.2]octane, and reduction of the oxo group to a methylene group with lithium aluminum hydride.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 10, pp. 1369–1371, October, 1970.     

1-氮杂环[2.2.2]辛烷的高效合成

将4-（2-羟乙基）哌啶蒸汽在425 ℃下通过CNM-3型固体酸催化剂进行分子内脱水反应,一步合成了目的产物1-氮杂环[2.2.2]辛烷（奎宁环）,4 h内25 g 4-（2-羟乙基）哌啶蒸汽单程收率可达76.8%,最高收率84.3%。 该方法原料易得,适合于奎宁环的工业化制备。     

Polyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings

Polyesters containing bicyclo[2.2.2]octane and bicyclo[3.2.2]nonane rings are prepared from 1,4-bis(carboethoxy)bicyclo[2.2.2]octane, 1,4-bis(hydroxymethyl)bicyclo[2.2.2]-octane and the 1,5-disubstituted bicyclo[3.2.2]nonane analogs. These polyesters are compared to the related polymers containing 1,4-phenylene and trans-1,4-cyclohexylene rings in terms of their melting point, thermal stabilities and oxidative stabilities. The lower symmetry of the bicyclo[3.2.2]nonane ring produces lower-melting polymers than the other ring systems. The remaining three rings are approximately equivalent in their effect on the melting point of a polymer provided that no more than one bicyclo[2.2.2]octane ring is present per polymer repeat unit. Two such rings produce a highermelting polymer than any other combination. Both the thermal and oxidative stabilities of the polyesters is improved by the presence of the bicyclo rings. This is attributed to the rings providing an approximation of a ladder polymer.     

Synthesis of crownophane with the bicyclo[2.2.2]octane core

Russian Chemical Bulletin -     

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.     

Synthesis of bicyclo[2.2.2]octane-2,3,5,6,7,8 hexols (Bishomoinositols) as glycosidase inhibitors

For the construction of the bicyclo[2.2.2]octane skeleton, 2,2-dimethyl-3a,7a-dihydro-1,3-benzodioxole was reacted with vinylene carbonate to give two isomeric cycloadditon products having the bicyclo[2.2.2]octane skeleton. Hydrolysis of the ketal ring and the opening of the carbonate functionality, followed by hydroxylation of the remaining double bond resulted in the formation of a symmetrical hexol. Epoxidation of the double bond in the cycloaddition products and the subsequent ring-opening reactions produce two additional hexol derivatives. One of the synthesized molecules exhibited enzyme-specific inhibition against alpha-glycosidase.     

1,4-二氮杂双环[2.2.2]辛烷催化的有机化学反应

综述了有机小分子催化剂1,4-二氮杂双环[2.2.2]辛烷(DABCO)在有机合成反应中的应用与发展。这种有机小分子催化的反应大多数条件温和、操作简单;相对过渡金属而言,对环境友好;在一定条件下,这种催化剂可以回收再利用。     

Conformation perturbation of p-sulfonatocalix[5]arene via complexation of 1,4-diazabicyclo[2.2.2]octane

A novel conformation of p-sulfonatocalix[5]arene has been established in the solid state with two calixarenes organised in a 'bis-molecular capsule' shrouding two di-protonated DABCO molecules and two water molecules within.