6-Methyl-2- hepta-1,5-diene

Andere 1-substituierte Butadiene, die ebenfalls in ditaktische Poly-mere iiberfiihrt wurden, sind 1,3-Hexadien (III), 1,3-Heptadien (IV), 1,3-Octadicn. (V), 5-Methyl-l,3-hexadicn (VI) und 6-Methyl-l,3-hepta-dien (VII) (73). 

Methylheptadecyl 16-methyl heptadecanoate. See Isostearyl isostearate Methyl heptadienone 2-Methyl hepta-2,4-dien-6-one. See 6-Methyl-3,5-heptadien-2-one 6-Methyl-3,5-heptadien-2-one CAS 1604-28-0 EINECS/ELINCS 216-507-7 Synonyms Methyl heptadienone 2-Methyl hepta-2,4-dien-6-one 6-Methylhepta-3,5-dien-2-one... 

Azabicyclo[4.1.0]hept-3-enes, e. g. 13, are available from 1,4-dihydrobenzenes 12 by the route indicated, and are useful precursors for the synthesis of specifically substituted 1//-azepines free from isomeric contamination.61 For example, low temperature addition of bromine to bicycle 13 yields the dibromo derivative 14 which, with powdered sodium methoxide in tet-rahydrofuran, undergoes a double dehydrobromination followed by electrocyclic ring opening of the resulting 7-azabicyclo[4.1.0]hepta-2,4-diene 15 to give methyl l//-azepine-l-carboxylate (16). 

However, if the azepine is C-monosubstituted, e.g. 14, or unsymmetrically substituted, then two isomeric 2-azabicycloheptadienes, e. g. 15 and 16, may result corresponding to electrocyclic ring closure involving C2-C5 or C4-C7 of the azepine ring. In practice, the ratio of the two isomers formed (which may be separated by vapor phase chromatography) varies with the position of the substituent.236 In contrast, irradiation of methyl 2,5-di-tm-butyl-l//-azepine-l-carboxylatein methanol yields only methyl 3,5-di-tert-bulyl-2-azabicycIo[3.2.0]hepta-3,6-diene-2-carboxylate (81 %).70... 

Attempts to methylate the carbanion derived from ethyl 2-(diethylamino)-5-phenyl-3//-azepine-3-carboxylate (14) with iodomethane leads to the formation of the 3-azabicyclo[4.1.0]cyclo-hepta-2.4-diene 15.225... 

Benzoyl-l-methyl-3,4-benzo-2-azabicyclo[3.2.0]hepta-3.6-diene (3) at 250"C yields exclusively l-benzoyl-2-mcthyl-l//-l-benzazepine (4).23 In contrast, silvcr(I) ion catalyzed ring expansion of 3 yields a mixture of the rearranged bicycle 5 (43 %), starting material (43 %), and the isomeric 1 H-l-benzazepines 4 (8%) and 6 (4%).23... 

Every example with a cyclohexene has proved hydrosilation to be very slow and difficult, but this difficulty was not experienced with cyclopen-tene structures by Petrov et al. (27). A number of chlorosilanes were added to bicyclo-(2,2,l)-hept-5-ene, bicyclo-(2,2, l)-hepta-2,5-diene, 2-methyl- and 2-vinylbicyclo-(2,2,l)-hept-5-ene, and dicyclopentadiene under mild conditions. Particularly surprising was the example of Eq. 

A thiepin derivative (382) has been reported to be formed in the reaction of 3-methyl-4-pyrrolidinylthiophene with DMAD. The initial adduct, 5-pyrrolidino-2-thiabicyclo[3.2.0]hepta-3,6-diene (381), formed around —30°, isomerizes to dimethyl 6-methyl-5-pyrrolidinylthiepine-3,4-dicarboxylate (382) [Eq. (58)]. ... 

Hept-6-en-2-ol, (E) -5 -iso-propyl- 7 - (2-methy-tetrahydro-fur-2-yl) Lf Hept-6-en-2-one, (E)-5-iso-propyl-7-(2-methyl-tetrahydro-fur-2-yl) Lf Hepta-4-(E)-6-dienoic acid, 3-iso-propyl-6-methyl, methyl ester Cured Lf 0.075 Hepta-4-6-dien-l-ol, 3-iso-propyl-6-methyl, (E) Lf ... 

Recently, a new reactivity index has been proposed (80H(14)1717> which predicts accurately the site selectivity of photocyclization of substituted cycloheptatrienes to their bicyclic valence tautomers. Unfortunately, application of the method to substituted lH-azepines is far less successful. For example, for 2-methyl-l-methoxycarbonyl-lH-azepine (37 R = 2-Me) AGrs values for C-2—C-5 and C-4—C-7 cyclization are calculated as 0.093 and 0.040 kJ mol-1, respectively, i.e. predicting the 1-methyl isomer (39) as the major product. Experimentally, however, the reverse is true, the yields being 93.5% for 3-methyl (38 R = Me) and 6.5% for 1-methyl (39 R = Me). The corresponding photoinduced valence isomerizations of 1-benzazepines to 3,4-benz-2-azabicyclo[3.2.0]hepta-3,6-dienes (38a) have been recorded (80JOC462). These isomerizations have also been achieved thermally in the presence of silver ion (80TL3403). 

The only NMR spectrum of a non-condensed borepin was recorded on a mixture, probably containing 1 -methyl- 1H-borepin (42) and 7-methyl-7-borabicyclo[4.1.0]hepta-2,4-diene. Signals at S 6.9-8.3 were attributed to the borepin hydrogens (sijom(215)303). However, some fused borepins have been isolated and their spectra recorded. 3-Phenyl-benzo[d]borepin (43) has been compared with 1-phenyl-4,5-dihydroborepin (44). The benzoborepin hydrogens give resonance at S 7.72 (Ha) and 8.22 (Hp) while the alkenic... 

Irradiation of alkyl tropyl ethers in ether solution gives a surprising result. Methyl tropyl ether (Formula 396) gives 1-methoxybicyclo-[3.2.0]-hepta-3,6-diene (Formula 397) (175). The photoisomer pyrolyzes... 

Acheson and Vernon,75 and later Gabel,76 studied reactions of methyl pyrrole-1-carboxylates (12a) with DMAD. They obtained the pyrroles 14 and identified the acetylene formed, but were unable to isolate the proposed intermediates, azabicyclo[2,2, l]hepta-2,5-dienes (13). The... 

Keywords 4-isopropyltropolone methyl ester, inclusion crystal, [2+2]photo-cycloaddition, bicyclo[3.2.0]hepta-3,6-dien-2-one, methyl-4-oxocyclopent-2-ene-... 

A crystalline powder of the 2 1 1 complex of (—)-l, 2 and CHC13 (4.44 g) was irradiated by a 400-W high-pressure Hg-lamp (Pyrex filter) in the solid state for 70 h. Separation of the reaction mixture by silica gel column chromatography gave a mixture of (-)-5-isopropyl-7-methoxybicyclo[3.2.0]hepta-3,6-dien-2-one 3 ([a]D-207° (c 0.23, CHC13), 96% ee) and (-)-methyl-l-isopropyl-4-oxocyclopent-2-ene-l-acetate 4 ([a]D-94.6 °(c 0.10, CHC13), 90% ee). The optical purities were determined by HPLC (Chiralcel OD, Daicel). 

Nitrile oxides react with the methyl enol ethers of (Rs)-l -fluoro-alkyl-2-(p-tolylsulfinyl)ethanones to produce (45,5/f,/fs)-4,5-dihydroisoxazoles with high regio-and diastereo-selectivity.87 In the 1,3-dipolar cycloaddition of benzonitrile oxide with adamantane-2-thiones and 2-methyleneadamantanes, the favoured approach is syn, as predicted by the Cieplak s transition-state hyperconjugation model.88 The 1,3-dipolar cycloaddition reaction of acetonitrile oxide with bicyclo[2.2.l]hepta-2,5-diene yields two 1 1 adducts and four of six possible 2 1 adducts.89 Moderate catalytic efficiency, ligand acceleration effect, and concentration effect have been observed in the magnesium ion-mediated 1,3-dipolar cycloadditions of stable mesitonitrile oxide to allylic alcohols.90 The cycloaddition reactions of acryloyl derivatives of the Rebek imide benzoxazole with nitrile oxides are very stereoselective but show reaction rates and regioselectivities comparable to simple achiral models.91. 

This reaction is used as one step [(7) to (6)] of the multistage synthesis of the monocyclic sesquiterpenic hydrocarbon, dehydro-a-curumene (3) [6-methyl-2-(4-methylphenyl)hepta-l,5-diene].247 The overall strategy is revealed from a retrosynthetic analysis for this compound, and is of interest since it emphasises the logic of the disconnection approach and draws together a number of important reactions which are relevant to this discussion of unsaturated compounds. 

Conversion into 6-methyl-2-(4-methylphenyl)hepta- 1,5-diene. 2- 4-methyl-phenyl)prop-2-enyl vinyl ether. A mixture of the foregoing allylic alcohol (2.5 g), ethyl vinyl ether (75 ml) and freshly crystallised mercury(n) acetate (600 mg) is refluxed continuously for 12 hours on a water bath. The reaction mixture is chilled in ice and mixed with 10 per cent aqueous sodium carbonate solution (25 g) and stirred well for 30 minutes at 0 °C. The organic layer is... 

Other examples are the photocyclization of suitably substituted W-methyl-N-aryl-enamins (Scheme 8), which may undergo rearomatization [115] (44 gives 0.2% ee in the product 45) or the internal cyclization of 2-methoxytropone 46 which results in the bicyclic ketone l-methoxy-bicyclo[3.2.0]hepta-3,6-dien-2-one (l-CH30-22) [116]. 

Diaza-bicyclo 3.2.0 hepta-2,6-diene l-Deutero-4-(methoxy-methyl)-4-methyl- E17f.. 764 (H - D)... 

Propanol l-Chlor-3-(4-methyl-phenyl)- Vl/la, 2, 1263 Spiro[2.4 hepta-4,6-dien l -Chlor-2,2-dimethyl-l-methoxy- E19b, 1660 (Carben + En)... 

Benzo c,d indol 4-Amino-2-oxo-l, 2-dihydro- XI/1, 151 3,4-Benzo-2-oxa-7-aza-bicyclo 3.2.0 hepta-3,6-dien 1-Cyan-8-methyl- IV/5b, 1307 1,3-Benzoxazepin 2-Cyan-4-meihyl-lV/5b, 1307/E9d, 307 (1 -CN — 3-R — isoquinolin-2-oxid hv)... 

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