3- Methyl, 1,5-heptadiene

Phoronediozonide(Sym-Dusopropylideneacetone-ozonide). C9H14O7, light green syrup, very expl, self-flammable on standing in air. Was prepd by Harries Turk by passing ozone thru a wed cooled chloroformic soln of phorone [2,4-di-methyl-heptadien-(2,5)-on-(4)], (CH3)2C CH.C0.CH C(CH3)2, foUowed by vacuum removal of chlf at 20°... 

Methyl-heptadien-(2.6).84iiie.(l) 2, 489. a-AUiybaorhinstiire M9, II455. y.E-Blmethyl-sorbinaiure 2, 489. 

Still another possibility of isomerization is illustrated by the easy interconversions between pentaphenylpentadienoie aeid chloride and 2-chloropentaphenyl-3-eyelopenten-l-one. Interestingly, 2,4,6-trimethylpjrrylium iodide maj be sublimed without decomposition in a vacuum, possibly as a covalent 6-iodo-4-methyl-3,5-heptadien-2-one or 2-iodo-2,4,6-trimethyl-2H-pyran valenee isomer. In a related case, chlorocyclopropenes are covalent and are converted into cyclo-propenium derivatives only by the action of Friedel-Crafts catalysts (electron-deficient metallic chlorides) (ef. also Section II,C, 2,c.)... 

The isomeric chloro-l-methylbenzo-2-azabicyclo[3.2.0]heptadienes 10a and 10b on heating under reflux in toluene rearrange in almost quantitative yields (90-95 %) to 9-chloro-l -methyl-1 H-benzazepine (11a) and its 6-chloro isomer lib, respectively.37... 

E)-3-methyl-2-pheriylsit fonyl-l,5-heptadien-4-ol yield 83% d.r. syn/anti) 90 10... 

Hydroxy-3 -methyl-3-[4-methyl-pentcn-(3)-yl]-2-[2,6-dimethyl-heptadien-(l,5)-yl]- 660... 

Reinhoudt et al.53) have reported the first synthesis of a monocyclic thiepin stabilized by electronic effects of the substituents. This synthesis utilizes the idea described in Section 2.3.3. 3-Methyl-4-pyrrolidinothiophene (85a) was treated in deuteriochloroform at —30 °C with dimethyl acetylenedicarboxylate. H-NMR monitoring of the reaction indicated that a [2 + 2]cycloaddition proceeded slowly at this temperature giving the 2-thiabicyclo[3.2.0]heptadiene (86a) which rearranged via ring opening of the cyclobutene moiety to the 4-pyrrolydinylthiepin (87a). At the... 

Kanasawud and Crouzet have studied the mechanism for formation of volatile compounds by thermal degradation of p-carotene and lycopene in aqueous medium (Kanasawud and Crouzet 1990a,b). Such a model system is considered by the authors to be representative of the conditions found during the treatment of vegetable products. In the case of lycopene, two of the compounds identified, 2-methyl-2-hepten-6-one and citral, have already been found in the volatile fraction of tomato and tomato products. New compounds have been identified 5-hexen-2-one, hexane-2,5-dione, and 6-methyl-3,5-heptadien-2-one, possibly formed from transient pseudoionone and geranyl acetate. According to the kinetics of their formation, the authors concluded that most of these products are formed mainly from all-(E) -lycopene and not (Z)-isomers of lycopene, which are also found as minor products in the reaction mixture. 

See 4-Hydroxy-4-methyl-1,6-heptadiene Ozone See other OZONIDES... 

Hydroxy-4-methyl-l,6-hepatadiene See 4-Hydroxy-4-methyl-l,6-heptadiene Ozone... 

Cyclopolymerization of Nonconjugated Dienes. Cyclopolymerization is an addition polymerization that leads to introduction of cyclic structures into the main chain of the polymer. Nonconjugated dienes are the most deeply studied monomers for cyclopolymerization and for cyclocopolymerizations with alkene monomers 66 In general, (substituted and unsubstituted) dienes with double bonds that are linked by less than two or more than four atoms cannot undergo efficient cyclization and result in crosslinked materials.12 In fact, efficient cyclopolymerization processes have been described, for instance, for a,oo-dienes like 1,5-hexadiene, 2-methyl-l,5-hexadiene, 1,6-heptadiene, and 1,7-octadiene,67 73 which lead to formation of homopolymers and copolymers containing methylene-1,3-cycloalkane units. 

Fluoroethylene ozonide, 0752 /rMaleic anhydride ozonide, 1406 f 2-Methyl-1,3-butadiene, Ozone, 1893 3-Methyl-l,2,4-trioxolane, 1235 trans-2-Pentene ozonide, 1982... 

Ethylcyclop entanon e 3-Pentyl cyclopentanone 6-Methyl-3,5-heptadien-2-one 6-Methyl-2-cyclohexen-l-one 2,3-Dihydrocarvone Unidentified dimethylacetophenone 2-Butyrylfuran Dimethyl disulfide 2,6-Dimethylpyridine Isobutylbenzene Unidentified acetal (mol mass 154) Isobutyronitrile... 

Attempted esterification of the 7-azabicyclo[2.2.1]heptadiene-2,3-dicarboxylic acids (5) and (10) with diazomethane in mild conditions led to decomposition liberating the corresponding pjnroles. Dimethyl acetylenedicarboxylate, the other decomposition product, reacted further with an excess of diazomethane to give dimethyl pyrazole-4,5-dicarboxylate and an A-methyl derivative. ... 

A different mode of cycloaddition occurs with 7-azabicyclo[2.2.1]-heptadiene derivatives, in which the nucleophilicity of the nitrogen atom determines the point of attachment of the electrophilic dienophile. The addition depicted in 87, which may occur in two steps via a zwitterionic intermediate rather than by a concerted mechanism, accounts for the structures (88) of 1 2 adducts obtained with A-methyl- or A-benzyl-pyrrole and dimethyl acetylenedicarboxylate. At a higher temperature the reaction with A-methylpyrrole also afforded the indole tetraester... 

Methyl 2-bromo-2-cyclopropylideneacetate (11a) has never been tested in these reactions, but has been used as a starting material for the stepwise construction of 1,6-heptadienes with methylenecyclopropane units for intramolecular Heck reactions. Thus, bromo ester 11a, after reduction, subsequent conversion of the resulting alcohol to the bromide and coupling with enolates of substituted malonates, was transformed into dienes of the type 254 (Scheme 73) - versatile synthetic blocks for the preparation of functionally substituted spirocyclopropanated bicyclo[4.3.0]nonenes 255a-d by a domino Heck-Diels-Alder reaction [122a]. 

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