1- Methyl-3,4-cyclohexadiene

SYNS a-FELLANDRENE FEMA No. 2856 4-ISOPROPYL-l-METHYL-l,5-CYCLOHEXADIENE 5-ISOPROPYL-2-METHYL-l,3-CYCLOHEXADIENE 2-METHYL-5-ISOPROPYL-l,3-CYCLOHEXADIENE a-PHELLANDRENE (FCC)... 

Cyclohexadiene, 2-methyl-5-(1-methylethyl)- a-phellandrene 172a 174a, 174b, 603, 3370... 

CAS 4221-98-1 EINECS/ELINCS 224-167-6 Synonyms 1,3-Cyclohexadiene, 2-methyl-5-(1-methylethyl)-, (R)- Isopropyl methylcyclohexadiene (R)-5-lsopropyl-2-methyl-1,3-cyclohexadiene (R)-5-lsopropyl-2-methylcyclohexa-1,3-diene 1,5-p-Menthadiene (-)-p-Mentha-l,5-diene a-L-Phellandrene R(-)-a-Phellandrene Empirical C10H16... 

Synonyms o-Fellandrene 4-lsopropyl-1-methyl-1,5-cyclohexadiene 5-lsopropyl-2-methyl-1,3-cyclohexadiene p-Mentha-1,5-diene 2-Methyl-5-isopropyl-1,3-cyclohexadiene 2-Methyl-5-(1 -methylethyl)-1,3-cyclohexadiene Classification Monocyclic terpene Empirical CioHie... 

Bromo-4-chloro-6-fluorophenol 4-Methyl-tra 5-2-heptene 1,4-Cyclohexadiene 2-Methyl-l-hexene-4-yne 1,3,5-Tribromobenzene... 

I,3-Cyclohexadienes Methyl tram-2,4-pentadienoate Cyclophanes 1,3-Dithiane. 

Methyl 6-hydroxy-3-methylhexanoate is our 1,6-difunctional target molecule. Obvious precursors are cyclohexene and cyclohexadiene derivatives (section 1.14). Another possible starting material, namely citronellal, originates from the "magic box of readily available natural products (C.G. Overberger, 1967, 1968 E.J. Corey, 1968D R.D. Clark, 1976). 

Barrelene was obtained via a double Diels-Alder reaction from a-pyrone with methyl acrylate (H.E. Zimmerman, I969A). The primarily forming bicyclic lactone decarboxylates in the heat, and the resulting cyclohexadiene rapidly undergoes another Diels-Alder cyclization. Standard reactions have then been used to eliminate the methoxycarbonyl groups and to introduce C—C double bonds. Irradiation of barrelene produces semibullvalene and cyclooctatetraene (H.E. Zimmerman. 1969B). 

The TT-allylpalladiLim complexes formed as intermediates in the reaction of 1,3-dienes are trapped by soft carbon nucleophiles such as malonate, cyanoacctate, and malononitrile[ 177-179). The reaction of (o-iodophenyl-methyl) malonate (261) with 1,4-cyclohexadiene is terminated by the capture of malonate via Pd migration to form 262. The intramolecular reaction of 263 generates Tr-allylpalladium, which is trapped by malononitrile to give 264. o-[odophenylmalonate (265) adds to 1,4-cyciohexadiene to form a Tr-allylpalladium intermediate via elimination of H—Pd—X and its readdition, which is trapped intramolecularly with malonate to form 266)176]. 

Aminophenyl)(4-imino-2,5-cyclohexadien-l-ylidene)methyl]-N-phenyl aniline, monohydrochloride [68966-31-4]... 

THBA from butadiene 2,5- (7( -methylene from 1,3-cyclopentadiene 4-methyl-THBA from 2-methylbutadiene 2,5- (7( -ethylene from 1,3-cyclohexadiene. 

From West Indian lime oil, a trace low Foiling constituent, 1-methyl-1,3-(or 1,5 /74< 5 -3 7- -cyclohexadiene has been characterized (27). This compound, which possesses an intense and characteristic lime aroma, was later confirmed to be the 1,3-isomer [1489-56-1] (11). This compound can easily be made in a biomimetic way through the reaction of citral [5392-40-5] (3,7-dimethyl-2,6-octadienal) with citric acid (28,29). 

BenZotrichloride Method. The central carbon atom of the dye is supphed by the trichloromethyl group from iJ-chlorobenzotrichloride. Both symmetrical and unsymmetrical triphenyhnethane dyes suitable for acryhc fibers are prepared by this method. 4-Chlorobenzotrichloride is condensed with excess chlorobenzene in the presence of a Lewis acid such as aluminium chloride to produce the intermediate aluminium chloride complex of 4,4, 4"-trichlorotriphenylmethyl chloride (18). Stepwise nucleophihc substitution of the chlorine atoms of this intermediate is achieved by successive reactions with different arylamines to give both symmetrical (51) and unsymmetrical dyes (52), eg, N-(2-chlorophenyl)-4-[(4-chlorophenyl) [4-[(3-methylphenyl)imino]-2,5-cyclohexadien-l-yhdene]methyl]benzenaminemonohydrochloride [85356-86-1J (19) from. w-toluidine and o-chloroaniline. 

Ai- 4-(bis[4-(phenylamino)phenyl]methylene)-2,5-cyclohexadien-l-ykdene -3-methyl-ben2eneaminesulfate [57877-94-8] (20) have been claimed as positive CCAs (65). The absorption spectra of the triaryknethane dyes can be extended into the near-infrared region. The use of triaryknethane dyes as infrared absorbers for optical information recording media (66) and as infrared color formers in carbonless copy paper has been claimed. 

Iron pentacarbonyl and l-methoxy-l,4-cyclohexadiene react as shown by Birch and oo-workera, but in dibutyl ether this solvent has been found superior. The tricarbonyl(methoxy-l,3-cyclohexadiene)iron isomers undergo hydride abstraction with triphenylmethyl tetrafluoro-borate to form the dienyl salt mixture of which the 1-methoxy isomer is hydrolyzed by water to the cyclohexadienone complex. The 2-methoxy isomer can be recovered by precipitation as the hexafluoro-phosphate salt. By this method the 3-methyl-substituted dienone complex has also been prepared from l-methoxy-3-methylbenzene. The use of the conjugated 1-methoxy-1,3-cyclohexadiene in Part B led to no increase in yield or rate and resulted chiefly in another product of higher molecular weight. An alternative procedure for the dienone is to react tricarbonyl(l,4-dimethoxycyclohexadiene)iron with sulfuric acid. ... 

Chemical Name 7-[D-2-amino-2-(1,4-cyclohexadien-1 -yl)acetamido] -3-methyl-8-oxo-5-thia-1-azabicyclo[4.2.0] oct-2-ene-2-carboxylic acid... 

The formed methylcyclohexane carbocation eliminates a proton, yielding 3-methylcyclohexene. 3-Methylcyclohexene can either dehydrogenate over the platinum surface or form a new carbocation by losing H over the acid catalyst surface. This step is fast, because an allylic car-bonium ion is formed. Losing a proton on a Lewis base site produces methyl cyclohexadiene. This sequence of carbocation formation, followed by loss of a proton, continues till the final formation of toluene. 

Oxo-3-methyl-3-trichlormethyl-cyclohexadien-(l,4) wird iiberwiegend zup-Kresol (76°/0 d.Th.) reduziert, der Mechanismus ist nicht klar3. 

Other examples that involve intermediate allyl cations are illustrated in Scheme 1.4. The cationic palladium(II) complex [Pd(dppp)(PhCN)2](BF4)2 coordinates the carbonyl oxygen of benzaldehyde and the activated carbonyl carbon attacks the isoprene, forming the allyl cation 10 which then cyclizes to give the 4-methyl-6-phenyl-5,6-dihydro-2H-pyran [22]. 2-Oxopropyl acrylate 11, in the presence of trimethylsilyltrifluoromethane sulfonate (TMSOTf) and methoxytrimethylsilane (MeOSMT), generates the cation 11a which is an efficient dienophile that reacts easily with the cyclohexadiene to give the Diels-Alder adduct in good yield [23]. 

By using unactivated K-10 montmorillonite in the absence of solvent, the endo-exo selectivity of the cycloadditions of acrolein and methyl vinyl ketone with cyclopentadiene and cyclohexadiene is low [8] (Table 4.2, entry 3), while highly reactive dienophiles such as 1,4-benzoquinone and N-phenyl... 

Good yields and high diastereoselectivities were obtained by using zeolites in combination with Lewis-acid catalyst [21]. Table 4.7 illustrates some examples of Diels-Alder reactions of cyclopentadiene, cyclohexadiene and furan with methyl acrylate. Na-Y and Ce-Y zeolites gave excellent results for the cycloadditions of carbocyclic dienes, and combining these zeolites with anhydrous ZnBr2 further enhanced the endo diastereoselectivity of the reaction. An exception is the cycloaddition of furan that occurred considerably faster and with better yield, in comparison with the classic procedure [22], when performed in the presence of sole zeolites. 

The photo-induced exo selectivity was observed in other classic Diels-Alder reactions. Data relating to some exo adducts obtained by reacting cyclopentadiene or cyclohexadiene with 2-methyl-1,4-benzoquinone, 5-hydroxynaphtho-quinone, 4-cyclopentene-l,3-dione and maleic anhydride are given in Scheme 4.13. The presence and amount of EtsN plays a decisive role in reversing the endo selectivity. The possibility that the prevalence of exo adduct is due to isomerization of endo adduct under photolytic conditions was rejected by control experiments, at least for less reactive dienophiles. 

Indium trichloride [30] and methylrhenium trioxide [31] catalyze the aqueous Diels-Alder reaction of acrolein and acrylates with cyclic and open-chain dienes. Some examples of the cycloaddition of methyl vinyl ketone with 1,3-cyclohexadiene are reported in Scheme 6.18. MeReOs does not give satisfactory yields for acroleins and methyl vinyl ketones with substituents at the jS-position and favors the self-Diels-Alder reaction of diene. 

Such cyclohexadienes are easily oxidizable to benzenes (often by atmospheric oxygen), so this reaction becomes a method of alkylating and arylating suitably substituted (usually hindered) aryl ketones. A similar reaction has been reported for aromatic nitro compounds where 1,3,5-trinitrobenzene reacts with excess methyl-magnesium halide to give 2,4,6-trinitro-l,3,5-trimethylcyclohexane. Both... 

Modification of the cyclohexenyl moiety has been carried out by use of the cyclohexadiene epoxides 243 and 244, which were coupled with methyl 4-amino-4-deoxy- and -4,6-dideoxy-0 -D-glucopyranoside (385a and 385b) to give the isomers (395 and 396). 

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