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2-ethyl-1,3-cyclohexadiene

The chiral BOX-metal(II) complexes can also catalyze cycloaddition reactions of other ketonic substrates [45]. The reaction of ethyl ketomalonate 37 with 1,3-conju-gated dienes, e.g. 1,3-cyclohexadiene 5c can occur with chiral BOX-copper(II) and zinc(II) complexes, Ph-BOX-Cu(OTf)2 (l )-21a, and Ph-BOX-Zn(OTf)2 (l )-39, as the catalysts (Scheme 4.29). The reaction proceeds with good yield and ee using the latter complex as the catalyst. Compared to the copper(II)-derived catalyst, which affects a much faster reaction, the use of the zinc(II)-derived catalyst is more convenient because the reaction gives 94% yield and 94% ee of the cycloaddition product 38. The cycloaddition product 38 can be transformed into the optically active CO2-... [Pg.175]

Cyclohexadiene has been prepared by dehydration of cyclohexen-3-ol,3 by pyrolysis at 540° of the diacetate of cyclohexane-1,2-diol,4 by dehydrobromination with quinoline of 3-hromocyclohexene,6 by treating the ethyl ether of cyclohexen-3-ol with potassium bisulfatc,6 7 by heating cyclohexene oxide with phthalic anhydride,8 by treating cyclohexane-1,2-diol with concentrated sulfuric acid,9 by treatment of 1,2-dibromocyclo-hexane with tributylamine,10 with sodium hydroxide in ethylene glycol,10 and with quinoline,6 and by treatment of 3,6-dibromo-cyclohexene with sodium.6... [Pg.33]

The Diels Alder reactions of maleic anhydride with 1,3-cyclohexadiene, as well the parallel reaction network in which maleic anhydride competes to react simultaneously with isoprene and 1,3-cyclohexadiene [84], were also investigated in subcritical propane under the above reaction conditions (80 °C and 90-152 bar). The reaction selectivities of the parallel Diels-Alder reaction network diverged from those of the independent reactions as the reaction pressure decreased. In contrast, the same selectivities were obtained in both parallel and independent reactions carried out in conventional solvents (hexane, ethyl acetate, chloroform) [84]. [Pg.287]

The use of chiral bis(oxazoline) copper catalysts has also been often reported as an efficient and economic way to perform asymmetric hetero-Diels-Alder reactions of carbonyl compounds and imines with conjugated dienes [81], with the main focus on the application of this methodology towards the preparation of biologically valuable synthons [82]. Only some representative examples are listed below. For example, the copper complex 54 (Scheme 26) has been successfully involved in the catalytic hetero Diels-Alder reaction of a substituted cyclohexadiene with ethyl glyoxylate [83], a key step in the total synthesis of (i )-dihydroactinidiolide (Scheme 30). [Pg.118]

Briliant Blue FCF (E 133, FD C Blue No. 1, Cl Food Blue 2) is a triarylmethane dye disodium 3-[N-ethyl-N-[4-[[4-[N-ethyl-N-(3-sulfonatobenzyl)-amino] phenyl] (2-sulfonatophenyl)methylene]-2,5-cyclohexadiene-l-ylidene]ammoniome-thyl] benzenesulfonate (or disodium (4-(N-ethyl-3-sulfonato-benzylamino) phenyl)-a-(4-N-ethyl-3-sulfonatobenzylamino)cyclohexa-2,5-dienylidene)-toluene-2-sul-... [Pg.605]

Isopropyl-4-m ethyl-1,4-cyclohexadiene, tl 1 Isovaleric acid, ml84 4-Ketovaleric acid, o63... [Pg.251]

The same, understandable bias towards the preferred use of man-made catalysts, rather than biocatalysts, continues in the area of hetero-Diels-Alder reactions1141-1. For example, in the presence of 5mol% of copper complexes of the type (47), cyclohexadiene and ethyl glyoxylate produce the oxabicyclooc-tene (58) (66% yield, 97% ee)[142]. [Pg.36]

Coumassie R250 N-[4-[[4-[(4-ethoxyphenyl)amino]phenyl][4-[ethyl[(3-sulphophenyl) methyl] amino]phenyl]methylene] -2,5-cyclohexadien-1 -y lidene] -N-ethyl-3-sulphobenzenemethan-aminium monosodium salt... [Pg.387]

In recent years, much work has been done on catalyzed and asymmetric cycloaddition reactions. In the presence of 5 mol% bismuth trichloride, the simple dienes 10 (R1 = R" = H R1 = H, R2 = Me or R1 = Me, R2 = H) react with diethyl mesoxalate to afford mixtures of the cycloadducts 11 and the products 12 of an ene-reaction (equation 13)11 12. 1,3-Cyclohexadiene and ethyl glyoxylate give solely the endo adduct 13 in 50% yield (equation 14)12. [Pg.485]

Raney-nickel was found to be selective in the hydrogenation of cyclopentadiene and cyclohexadiene and of their methyl and ethyl derivatives at 0-40 °C and 2-5 bar pressure137,138. The skeletal nickel proved to be selective in the semihydrogenation of conjugated polyenic compounds (equation 52)139. [Pg.1014]

The interesting m-menthadienol (3S)-l-methyl-5-(l-hydroxy-l-methyl-ethyl)-l,3-cyclohexadiene 253, is produced by Ips sexdentatus, boring under stress in 3-carene-rich, highly resinous pine trees and possibly released as a kind of warning signal to conspecifics to keep off [463]. [Pg.161]

The starting material 4 is easily prepared in 88% yield by a Diels-Alder reaction of 1,3-cyclohexadiene and ethyl acrylate as described by Skeda and Tramposch [5] (Scheme 13.1.5). Whitlock found by v.p.c. that the endo derivative is by far the... [Pg.341]

Alkyl groups differ as to ease of elimination. When 5-methyl-5-ethyl-l,3-cyclohexadiene is reacted over a sodium-organosodium catalyst, methyl groups are eliminated more easily than ethyl groups (B ). [Pg.125]

The metal complexes even with tropos ligands can thus be used as asymmetric catalysts for carbon-carbon bond-forming reactions in the same manner as atropos catalysts. The single diastereomer (7 )-32/(/ )-DABN can be employed as an activated asymmetric catalyst for the Diels-Alder reaction at room temperature (Table 8.11). The high chemical yield and enantioselectivity (62%, 94% ee) in the Diels-Alder reaction of ethyl glyoxylate with 1,3-cyclohexadiene are obtained... [Pg.249]

Similar results were achieved when benzene was reduced with alkali metals in anhydrous methylamine at temperatures of 26-100°. Best yields of cyclohexene (up to 77.4%) were obtained with lithium at 85° [396]. Ethylamine [397] and especially ethylenediamine are even better solvents [398]. Benzene was reduced to cyclohexene and a small amount of cyclohexane [397, 398] ethylbenzene treated with lithium in ethylamine at —78° gave 75% of 1-ethyl-cyclohexene whereas at 17° a mixture of 45% of 1-ethylcyclohexene and 55% of ethylcyclohexane was obtained [397], Xylenes m- and p-) yielded non-conjugated 2,5-dihydro derivatives, l,3-dimethyl-3,6-cyclohexadiene and 1,4-dimethyl-1,4-cyclohexadiene, respectively, on reduction with sodium in liquid ammonia in the presence of ethanol (in poor yields) [399]. Reduction of diphenyl with sodium or calcium in liquid ammonia at —70° afforded mainly 1-phenylcyclohexene [400] whereas with sodium in ammonia at 120-125° mainly phenylcyclohexane [393] was formed. [Pg.48]

It has been shown that complete selectivity for the hetero-Diels-Alder cycloadduct 109 (100% endo, 60% ee) can be achieved in the hetero-Diels-Alder reaction of 1,3-cyclohexadiene 108 and ethyl glyoxylate 99 using ent-6 and copper(II) triflate derived catalyst complex. Another interesting reaction introduced by Jprgensen and co-workers was the reaction between 1,3-cyclohexadiene 108 and diethyl ketomalonate 110 to form cycloadduct 111 in 76% yield with an ee of 84% (Fig. 9.35b, p. 558). ... [Pg.555]

Die selektive Nitrierung von Oxidations-anfalligen Hydroxy-arenen, z. B. 1-Hydroxy-naphthalinen, wird bevorzugt mit 3-Methyl- bzw. 3-Ethyl-3-nitro-6-oxo-tetrabrom-1,4-cyclohexadien in Diethylether bei 20° durchgefuhrt1,2 ... [Pg.339]

Ethyl 2,6,6,trimethyl-l,3-cyclohexadiene-l-carboxylate [35044-59-8, the commercial quality also contains the a.- [25044-57-6] and 7-isomers isomers [35044-58-7]... [Pg.73]

Careful temperature control is important, or the yield of product is reduced and considerable quantities of the by-product l-methyl-3-ethyl-l,3-cyclohexadiene are produced. [Pg.1100]


See other pages where 2-ethyl-1,3-cyclohexadiene is mentioned: [Pg.290]    [Pg.284]    [Pg.207]    [Pg.146]    [Pg.349]    [Pg.22]    [Pg.168]    [Pg.174]    [Pg.1010]    [Pg.192]    [Pg.203]    [Pg.113]    [Pg.87]    [Pg.487]    [Pg.521]    [Pg.369]    [Pg.339]    [Pg.1056]    [Pg.276]    [Pg.781]    [Pg.154]    [Pg.323]    [Pg.154]    [Pg.180]    [Pg.679]    [Pg.1698]    [Pg.185]    [Pg.22]    [Pg.97]   
See also in sourсe #XX -- [ Pg.284 ]




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