Dienoic esters

While linear dimerization of dienoic esters can also be accomplished with nickel-AMP systems, other functionalized dienes undergo little or no conversion. The reaction of methyl hexa-2,4-dienoate, 81, furnishes diastereomeric trienoic diesters (82) in high yields (equation 43). 

Selected examples of the dithionite reduction of alkane-2,4-dienoic esters... 

In addition to 1,2-alkyl shifts, sulfonium ylides with P-hydrogen can also undergo fragmentation into an olefin and a thioether [1317,1318]. When allylic thioethers are treated with two equivalents of ethyl diazoacetate in the presence of a catalyst for diazodecomposition, S-alkylation and elimination of the thioalkyl group from the initially formed a-alkylthio-4-alkenoic esters occurs to yield 2,4-dienoic esters [1319]. 

Rearrangement of P—Allenic Esters to (E,Z)-2,4-Dienoic Esters with Alumina ... 

E,4Z)-Dienoates.7 /f-Allenic esters rearrange to (2E,4Z>dienoic esters when heiltcd at 80-138° in benzene or xylene with slightly basic alumina. The Htcrcoselecti vity is 91-100%, but the yields are only moderate to good. 

Bougioukou DJ, Smonou I (2002) Chloroperoxidase-Catalyzed Oxidation of Conjugated Dienoic Esters. Tetrahedron Lett 43 339... 

Isomerization of alkynes.1 This complex (1) or IrH5[P(/-Pr)3]2 (2) in combination with Bu3P catalyzes isomerization of 2-ynoic esters to (2E,4E)-dienoic esters at 80-100° in yields generally of about 80-90%. 

Cyclization of 2,6-octadienoic estersLSA adds 1,4 to crotonoates. Extension of this reaction to these dienoic esters (1 and 2) results in cyclization to cvclopentanes (3) and cyclohexanes (4), respectively. 

Ketene acetals 247, prepared in situ from racemic y-hydroxy vinyl sulfones 246, underwent Claisen rearrangements to give 3-phenylsulfonyl esters 248. These compounds were converted to the (2E,4 )-dienoic esters 249 by a base-assisted elimination of benzenesulfinic acid (Scheme 62).131... 

Thiazol-2-yl allyl sulfides react with organomagnesium compounds in the presence of CuBr to afford optically active alkenes in good yields and selectivities <1996T10799>. Thiazole and benzothiazole allyl sulfides have been shown to react with excess ethyl diazoacetate in the presence of a copper(i) hexafluorophosphate acetonitrile complex to give, via formation of the resultant homoallylic sulfide intermediates, conjugated dienoic esters in good yields <1997TL3289>. /3-Ketosulfides of benzothiazole 143 are very prone to deprotonation by weak bases. Treatment... 

Acetylfiirans. 3,5-Alkadien-2-ones are oxidized to the furan derivatives by selenium dioxide in refluxing benzene, although in moderate yields for many cases. Dienoic esters, amides, and nitriles do not react in the same manner. 

Similar y-condensations of allylidenephosphoranes involving Michael addition to conjugated dienoic esters lead to bicyclo[4,l,0]heptanes, as shown in Scheme 3. ... 

Maleimide formation from 2,3-dienoic esters and isonitriles is a cycloaddition catalyzed hy Zn(OTf)2 under 02- ... 

Coupling reactions. Carbostannylation of the palladacyclopentadiene intermediates derived from two molecules of alkynoic esters leads to dienoic esters that also bear a reactive stannyl residue. ... 

Hydrogen fluoride-amine. 16, 286-287. I Oxidative fluorination. y,8-Difluoro anode when dienoic esters are subjected ti. A chemical process employing 3HF-Et-,N 3-halotetrahydropyrans and ally alcohol case study, only with NBS). 

Oxidative fluorination. "y,8-Difluoro-ct, 3-unsaturated esters are produced at a Pt anode when dienoic esters are subjected to electrolysis in MeCN containing 3HF-EtjN. A chemical process employing 3HF-Et,N and NXS converts dihydropyran into 2-fluoro-... 

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