Ethyl 3,4-hexadienoate

The periselectivity of the reaction of a given diene with tropone is critically dependent on temperature. The variable course of the cycloaddition of ( )-l-trimethylsilyloxybutadiene with tropone as a function of reaction temperature is a Carnatic illustration of this phenomenon. At 80 C the major adduct is bicy-clo[4.4.1]undecenone (10), whereas in refluxing xylene the [4 + 2] cycloadduct (11) prevails as a mixture of regioisomers. A further example of the dichotomy between [6 + 4] and [4 + 2] reaction pathways can be seen with (Z)-l-acetoxybutadiene, which provides some [6 + 4] cycloadduct along with larger quantities of various [4 -i- 2] pr ucts as depicted in equation (1). In contrast to these results, dienes such as ethyl 2,4-hexadienoate and furan do not yield any [6 + 4] or [4 2] products when heated with tropone. The latter result, in particular, may be reflective of the reversibility of the furan cycloadducts. Various furan derivatives do provide modest yields of mixtures of endo and exo [4 + 2] cycloadducts with tropone when reacted together at 3 kbar and 130 C. ... 

C8H13N3O4, Mr 215.21, mp. 140°C, optically inactive, isolated from cultures of Streptomyces griseosporeus after acidification (pH 3) prior to extraction. It is also obtained semisynthetically from FR-900411 (4-ethyl-2,4-hexadienoic acid amide CjH,3NO, Mr 139.20, mp. 57-58°C) produced by the strain through reduction... 

See Cetethyidimonium bromide Ethyl-N-hexadecylmorpholinium ethosulfate Ethyl-4-hexadecylmorpholinium ethyl sulfate. See Cetethyl morpholinium ethosulfate Ethyl-2,4-hexadienoate. See Ethyl sorbate Ethylhexaldehyde 2-Ethylhexaldehyde Ethyl hexanal. See 2-Ethylhexanal 2-Ethylhexanal... 

Synonyms Ethyl-2,4-hexadienoate Sorbic acid ethyl ester... 

Ethyl-2,4-hexadienoate, 2,5-Af-P-D-Acetylglucosamine, 1,4- (chitin) tert-Butylmethacrylate 2,3,4-trimethoxy-5-hydroxyvaleric acid 2,5-Dimethylterephthalaldehyde lsobutyl-2,4-hexadienoate, 2,5-p-D-Galactosamine-a/t-l,4-P-D-glucuronic acid, 1,3-P D-Glucosamine-a/t-1, 4-p-D-glucuronic acid, 1,3-... 

Melon Cinnamaldehyde Ethyl hexadienoate Methyl amyl ketone Octyl butvrate. 

Ethyl 3-anilinocrotonate (82) undergoes reaction with dimethyl acetylene-dicarboxylate (57) with the formation of two products, ethyl 5-anilino-3,4-dicarbomethoxy-trfl s,cM-2,4-hexadienoate (83) and ethyl 5-anilino-3,4-dicarbomethoxy-ci5, cw-2,4-hexadienoate (84). 

The synthesis of chaparrinone and other quassinoids (naturally occurring substances with antileukemic activity) is another striking example [16a-c]. The key step of synthesis was the Diels-Alder reaction between the a,/l-unsaturated ketoaldehyde 1 (Scheme 6.1) with ethyl 4-methyl-3,5-hexadienoate 2 (R = Et). In benzene, the exo adduct is prevalent but it does not have the desired stereochemistry at C-14. In water, the reaction rate nearly doubles and both the reaction yield and the endo adduct increase considerably. By using the diene acid 2 (R = H) the reaction in water is 10 times faster than in organic solvent and the diastereoselectivity and the yield are satisfactory. The best result was obtained with diene sodium carboxylate 2 (R = Na) when the reaction is conducted 2m in diene the reaction is complete in 5h and the endo adduct is 75% of the diaster-eoisomeric reaction mixture. 

Pineapple Allyl capruale, cyclohexylacetaie. cyclohexylbutyrate, cyclohexylptopionate. 2-nonylenate, phenoxyacetate Benzyl formate Bomyl acetate n-Bulyl acetate Butyl isobutyrate Cinnamyl acetate Decanal dimethyl acetal Ethyl butyrate, hexadienoate. phenoxyacetate Hexyl butyrate 2-Methylallyl capruale Methyl heia-methy Ipropionaie Methyl undecylate Propyl isobutyrate. 

On heating at 160°C in the presence of catalytic amounts of copper bronze or copper(l) chloride, ethyl 2-methoxy-2-vinylcyclopropanecarboxylates (220) undergo ring expansion into the isomeric 3-methoxy-2-cyclopentene (221) and 3-methoxy-3-cyclo-pentenecarboxylates (222) equation 146) on the other hand platinum and rhodium complexes catalyse the ring-opening into ethyl-4-methoxy-3,5-hexadienoate. ... 

Hexadienoate Ethyl 3-Ethyl- 2786 Methyl- 3-Propyl- 2785 Octane... 

The oldest syntheses of chrysanthemates are those starting from 2,5-dimethyl-2,4-hexadiene (238). There have been more papers on the use of rhodium or antimony to catalyze the addition of diazoacetate and chiral copper complexes to create asymmetry during the addition (see Vol. 4, p. 482, Refs. 219-222). The problem with this route is to avoid the use of diazo compounds. An old synthesis of Corey and Jautelat used the ylide addition of a sulfurane to a suitable precursor (in this case a C3 unit was added to methyl 5-methyl-2,4-hexadienoate, 239), and a recent paper gives details about the addition of ethyl dimethylsulfuranylideneacetate to 2,5-dimethyl-4-hexen-3-one (240). This led exclusively to the tran -isomer 241, from which ethyl trans-chrysanthemate (185, R = Et) was made. Other ylide additions are mentioned below. 

M. P. S. Ishar, R. P. Gandhi. Tetrahedron 47, 2211 (1991) analogous results with ethyl 4-elhyl-2,3-hexadicnoate and ethyl 4-methyl-2,3-hexadienoate. 

Higher seleetivities in the cyelopropanation step are observed with ethyl (/7)-2-dia7o-6-phenyl-3,5-hexadienoate (21)824. Only cw-l,2-divinylcyclopropanes are formed, which immediately rearrange to give cyeloheptadienes. The yields can be improved by using rhodium(II) hexanoate instead of rhodium(II) acetate and by lowering the temperature to 0°C. However, the use of 21 is also accompanied by a drop in the regioselectivity of the cyelopropanation step. 

Ethyl 2ff-pyran-2-carboxylate (32) 6-Ethoxy-2tf-pyran-2-carboxaldehyde (33) (Z -6-Oxo-2,4-hexadienoic acid (Sda) ( ,Z)-6-Oxo-2,4-hexadienoic acid (34b) (Z, )-6-Oxo-2,4-bexadienoic acid (34c) ( JS)-6-Oxo-2,4-hexadienoic acid (34d) 4-Caifaoxyinethylbut-2-eii-l,4-olide (muconolactone) (37) Bicyclo[S.1.0]octa-2,4-diene (41) (Z Octa-l,3.5,7-tetraene (42) ... 

Ketene ethyl er -butyldimethylsilyl acetal followed by triethylamine added with ice-cooling under Ng to a soln. of crotonyl diloride in dry tetrahydrofuran, then the ice bath removed, and stirred 24hrs. at room temp. -> ethyl 3- er -butyl-dimethylsiloxy-3,5-hexadienoate. Y 90%. - Similarly with butyryl diloride -> ethyl 3-rerr-butyldimethylsiloxy-3-hexenoate. Y 85% with acetyl diloride and n-pentylketene ethyl rer -butyldimethylsilyl acetal ethyl 3- er -butyldimethyl-siloxy-2- -pentyl-3-butenoate. Y 61%. F. e. s. M. W. Rathke and D. F. Sullivan, Tetrah. Let. 1973, 1297. 

Ethyl 3,4-pentadienoate, 203 - (S) Ethyl 3,4-hexadienoate, 204 - (0) 2,2-Dimethyl-3,4-pentadienal, 204 - (7) 3-Hethyl-l,2-butadienyl acetate (l-acetoxy-3-methyl-l,2-butadiene), 205... 

In an early application, the aqueous Diels-Alder reaction of diene carboxy-lates was used to effect a very concise synthesis of the vemolepin precursor 5.2 [60]. This compound had previously been prepared by Schlessinger via another route in 11 steps from ethyl crotonate [61]. Reaction of the substituted methacrolein 5.3 with sodium ( )-3,5-hexadienoate (5.4) in water proceeded at 50 C to give the Diels-Alder endo adduct 5.5 along with a minor amount of the exo adduct (not shown) quantitatively in a ratio of 10/1 (Scheme 1.4). Sodium borohydride was added directly to this reaction mixture to produce the 6-hydroxycarboxylate 5.6, which lactonized spontaneously upon acidic workup. This one-pot operation resulted in the isolation of vemolepin AB-ring... 

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