Norbornene bicyclo heptene

Besides of ethene also other alkenes react with carbon dioxide in the presence of nickel(0) complexes. Some examples are given in Figure 6. Hexenes lead to different isomeric heptanoic acids, styrene reacts to cynnamic acid and norbornene (bicyclo 2.2.1 heptene) gives the exo-norbornane-2-carboxylic acid in 95 % yield [5,12,13]. Nor-bornadiene which contains two isolated double bonds reacts to a monoaddition product whose decomposition with hydrochloric acid yields a mixture of six chloronorbornanecarboxylic acids with the chloro-and carboxy-substituents both in exo- and in endo-positions [14]. 

With the growing interest for the polynorbomene, photoresist polymer, and cyclic olefin copolymer, the synthesis norbornene or bicyclo[2,2,l]-2-heptene (NBN) has drawn significant attention because it is one of the most important precursor for these materials. Norbornene is produced by the reaction between ethylene and cyclopentadiene (CPD) via the Diels-Alder condensation process at elevated temperature and pressure [1,2]. 

SYNS BICYCLO(2.2.1)HEPTENE-2-DICARBOXYUC ACID, 2-ETHYLHEXYLIMIDE ENDOMETHYLENE-TETRAHYDROPHTHALIC ACID, N-2-ETHYLHEXYL IMIDE ENT 8,184 N-(2-ETHYLHEXYL)BICYCLO-(2,2,l)-HEPT-5-ENE-2,3-DICARBOXIMIDE N-2-ETHYLHEXYUMIDEENDOMETHYLENETETRAHYDR OPHTHALIC ACID N-(2-ETHYLHEXYL)-5-NORBORNENE-2.3-DICARBOXIMIDE 2-(2-ETHYLHEXYL)-3a.4,7,7a-TETRAHYDRO-4,7-METHANO-1H-ISOINDOLE-1,3(2H)-DIONE MGK-264 OCTACIDE 264 N-OCTYLBICYCLO-(2.2.1)-5-HEPTENE-2,3-DICARBOXEvnDE PYRODONE SYNERGIST 264 VAN DYK 264... 

Many examples of polycyclic alkene osmylations have been reported in the literature in connection with the syntheses of specific target molecules such as alkaloids, prostanoids, or steroids. However, carefully determined diastereomer ratios are usually not available. Due to the varied nature of these substrates, it is not possible to formulate definite rules for diastereo-face differentiation except in specific cases. Thus, for example, the exclusive exo reactivity of bridged systems such as bicyclo[2.2.1]heptene derivatives (norbornene-type) is well known as Alder s rule of exo addition63. 

Figure 29.25. The deuterium-labeled bicyclo[3.2.0]heptene V rearranges via a [1,3]-C shift to the norbornene VI. There is inversion of configuration at C-7 from R to S. (Or, using C-6 as our standard, we see that H eclipses OAc in V, and D eclipses OAc in VI.)...

Under similar conditions, the 2-methylenebicyclo[2.2.1]heptane, or norcamphene (7) was conYerted to the isomer 6, through the intermediate formation of 5, whose maximum concentration in the mixtures is about 10%. This slow reaction is complicated by extensive hydrogen transfer and polymerization reactions (20), leading to saturated bicyclic hydrocarbons 2-methylbicyclo[2.2.1]heptane (12), bicyclo[3.2.1]- and [3.3.0]octanes (15 and 17). Isomerization of norcamphene (7) to hydrocarbons of the bicyclo[2.2.1]heptane series is also noticed at 250° in the vapor phase, but this is the main reaction at 140° in the liquid phase with the same catalyst. The main products are then 2-methyl-bicyclo[2.2.1]-2-heptene (8), l-methylbicydo[2.2.1]-2-heptene (10), and l-methyltricyclo[2.2.1.0]heptane 11 (13). The tricyclic isomer has been observed in the liquid-phase silica-alumina-catalyzed conversion of norbornene (21). 

As well as [2-H]-addition products, in copper-catalyzed reactions with norbornadiene and bicyclo[2.2.1]heptene (norbornene) as reactive alkenes, [2 + 2] products are also formed. The selectivity of the reaction depends on the reaction temperature. At — 20°C a 90-95% selectivity for the [2 + 2] addition can usually be obtained with copper(I) chloride/triphenyl-phosphane or triphenyl phosphite als catalyst.At higher reaction temperatures, products... 

Reactions. The thermal decomposition of benzenesulfonyl azide gives radicals which react with aromatic hydrocarbons to give products of amidation.1-3 Like phenyl azide, benzenesulfonyl azide undergoes addition reactions with strained double bonds. Thus it reacts with norbornene (1, bicyclo[2.2.1 ]-2-heptene) with loss of nitrogen to give the azetidine (2) in nearly quantitative yield.2 The reaction is considered to involve the intermediate (a). In contrast the reaction... 

Almost exclusively reported for 1-alkenylcarbenes and 1-alkynylcarbenes are examples dealing with mechanism-based and simple diastereoselectivity. The diastereofacial selectivity has been occasionally examined with bicyclo[2.2.1]heptene (norbornene) derivatives which provide the expected exo-adducts, while enantioselective [2 + 1] cycloadditions of these carbenes or their equivalents have apparently not yet been studied. 

The copper alkenylcarbenoid generated from methyl 2-propyl-2-cyclopropene-l-carboxy-late adds to bicyclo[2.2.1]heptene (norbornene) with high diastereofacial selectivity affording the exo-adduct 9 in high yield9. 

A more stable tris(alkene) complex of Pd uses norbornene tris(bicyclo[2.2.1]heptene) ... 

Figure 4.52. A cartoon showing the consequences of the Diels-Alder reaction between cyclopentadiene and ethene to generate bicyclo[2.2.1]heptene (norbornene) and the subsequent catalytic reduction of the latter to produce bicyclo[2.2.1] heptane (norbomane).

Abbreviations aapy, 2-acetamidopyridine Aik, alkyl AN, acetonitrile Ar, aryl Bu, butyl cod, 1,5-cyclooctadiene COE, cyclooctene COT, cyclooctatetraene Cp, cyclopentadienyl Cp, penta-methylcyclopentadienyl Cy, cyclohexyl DME, 1,2-dimethoxyethane DMF, dimethylfonnaniide DMSO, dimethyl sulfoxide dmpe, dimethylphosphinoethane dppe, diphenylphosphinoethane dppm, diphenylphosphinomethane dppp, diphenylphosphinopropane Et, ethyl Fc, fetrocenyl ind, inda-zolyl Me, methyl Mes, mesitylene nb, norbornene or bicyclo[2.2.1 ]heptene nbd, 2,5-norbomadiene OTf, triflate Ph, phenyl PPN, bis(triphenylphosphoranylidene)ammonium Pr, propyl py, pyridine pz, pyrazolate pz, substimted pyrazolate pz, 3,5-dimethylpyrazolate quin, quinolin-8-olate solv, solvent tfb, tetrafluorobenzobatrelene THE, tetrahydrofuran THT, tetrahydrothiophene tmeda, tetramethylethylenediamine Tol, tolyl Tp, HB(C3H3N2)3 Tp, HB(3,5-Me2C3HN2)3 Tp, substituted hydrotris(pyrazol-l-yl)borate Ts, tosyl tz, 1,2,4-triazolate Vin, vinyl. 

An approximate reaction surface for the thermal 1,3-sigmatropic rearrangement of bicyclo[3,2,0]hept-2-enes to norbornenes has been calculated using extended Huckel theory, The potential surfaces, calculated for bicyclo[3,2,0]heptene and 7-methylbicyclo[3,2,0]heptene, accommodate qualitatively the known experimental facts, but results of quantitative significance would require a dynamical approach. 

Hasselman has investigated the thermal rearrangements at 190°C of the methylated methylenebicyclo[3,2,0]heptenes (498)—(501). Rate constants for the decomposition of each of the possible isomeric bicyclo[3,2,0]heptenes and bicyclo-[2,2,l]heptenes (502)—(505) have been calculated. The activation energies are ti-mated to lie in the range 38—41 kcal mol and are consistent with the formation of biradical intermediates (506) or (507). The results are not consistent with the intermediacy of freely rotating biradicals. In particular, the ratio of the rates of formation of the methylated norbornenes (502) and (503) from the bicyclo[3,2,0]heptenes (500) and (501) were found to be 1.33 and 1.43 respectively. If freely rotating biradicals were involved, the ratio of (502) and (503) formed from the isomeric bicyclo[3,2,0]heptenes (498) and (499) should lie between these values, irrespective of the stereochemistry of the methallyl portion of the biradical formed. In fact the ratios observed from (498) and (499) are not the same as those from (500) and (501). The intermediates therefore appear to be non-equilibrating biradicals, in which product formation competes with rotation about the central bond. 

The monomer, norbornene (or bicyclo 2,2,l-heptene-2) is produced by the Diels-Alder addition of ethylene to cyclopentadiene. This is then polymerized by a ring-opening mechanism to give a linear polymer with a repeat unit containing both an in-chain p-phenylene group and a double bond. Both cis- and trans- structures are obtainable according to the choice of catalyst used (Le Delliou, 1977). 

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