2-Methylbicyclo -5-heptene

Exclusive ring opening of the anti compound of a mixture of syn- and anti-1-methylbicyclo[2.2.1]heptene-2 in the presence of Ru-, Os-, Ir-, W-, and Re-based catalysts was observed116 proving that the exo face of norbomene is highly reactive while the endo face is inert toward metathesis. 

BA BuE-PA BE-HET BE-HHPA BE-MA BE-PA BE-SA CA CHX DMA DMBA DY 062 GA HEB HHPA HMTA MA MTHPA NMA benzoic acid monobutylester of phthalic acid monobenzylester of hexachloroendomethylenetetrahydrophthalic acid monobenzylester of hexahydrophthalic acid monobenzylester of maleic acid monobenzylester of phthalic acid monobenzylester of succinic acid citraconic anhydride cyclohexanol N,N-dimethylaniline dimethylbenzylamine high boiling tertiary amine (Ciba Geigy AG) gjptaric anhydride 2-hydroxy-4-(2,3-epoxypropoxy)benzophenone hexahydrophthalic anhydride hexamethylenetetramine maleic anhydride methyltetrahydrophthalic anhydride nadic methyl anhydride (methylbicyclo[2.2.1]heptene-2,3-dicarboxylic anhydride isomers)... 

Our further analysis of the enthalpy of formation of 2-methylbicyclo[2.2.1]heptene only worsens the disparity. That is, we find methylation of one doubly bonded carbon in gaseous cyclopropene, cyclopentene and cyclohexene is accompanied by a decrease in enthalpy of formation of 34, 38 and 38 kJmol-1, i.e. 36 2 kJmol-1. The recommended enthalpy of formation of bicyclo[2.2.1]heptene (see Reference 60) is 90 kJmol-1 and so we would predict an enthalpy of formation of its gaseous 2-methyl derivative of 90 — 36 54 kJmol-1. Using our standard enthalpy of vapourization estimation protocol we would predict a phase-change enthalpy of 40 kJmol-1 for this species, and so derive an enthalpy of formation of liquid 2-methylbicyclo[2.2.1]heptene of ca 54-40 15 kJmol-1. That is, if anything, the exocyclic species is too stable if we compare this derived value with 4.5 1.8 kJmol-1 derived from the available combustion calorimetric data. 

Bicyclo[2.2.2]-2-octene Bicyclo[3.2.1]-2-octene 2-Methylenebicyclo[2.2.1 ]heptane 2-Methylbicyclo[2.2.1 ]-S-heptene ... 

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). 

Fio. 14. Isomerization paths for bicyclic hydrocarbons. As an example of the abbreviations, Me[2.2.1]C7 indicates methylbicyclo[2.2.1]heptane or heptene isomers. 

Beilstein Handbook Reference) 5-Norbornene-2,3-dicarboxylic anhydride, methyl- BRN 0162395 EINECS 246-644-8 Epicure NMA Hardener HY906 HSDB 6093 Kayahard MOO MEA 610 4,7-Methanoisobenzofuran-1,3-dione, 3a,4,7,7a-tetrahydro-methyl-, Methendic anhydride Methyl-5-norbornene-2,3-dicarboxylic anhydride Methyl nadic anhydride Methylbicyclo(2.2.1)heptene-2,3-dicarboxylic anhydride isomers Methylendic anhydride Methylnorbornene-2,3-dicarboxylic anhydride Nadic methyl anhydride NMA TK10 524 XMNA. 

NMA nadic methyl anhydride (methylbicyclo[2.2.1]heptene-2,3-dicarboxylic anhydride... 

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. 

Russell has reported the preparation of bicyclo[3,2,0]hept-2-en-6,7-semidione (582). Reaction of the bicyclo[2,2,l]heptene acyloin (583) with potassium t-butoxide in DMSO gives (582). The rearrangement may occur via the enediol dianion, as the bicyclo[2,2,l]heptene semidione itself, generated by an alternative route, is stable. The methylated bicyclo[2,2,l]heptene acyloins (584a) and (584b) both yielded mixtures of the possible bicydo[3,2,0]heptene semidiones (585) and (586) on treatment with butoxide in DMSO. The rearrangement was shown to be reversible, since the same mixture of semidiones was formed from l-methylbicyclo[3,2,0]hept-2-en-6,7-acyloin (587). 

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