Methyl 2, 4-dimethyl-2,4-pentadienoate

In high polarity solvents, such as acetonitrile, dimethyl sulfoxide, methyl acetate, and methanol, the branched dimer, 4-methyl azelate precursor, is formed in high yield. In methanol, a methoxy dimer (CH302CCgH] 4(0013)0020113) is also formed in moderate yield. Heavies contain both an acyclic methyl, 4-pentadienoate trimeric product and high molecular weight methyl, 4-pentadienoate homopolymer. Polymerization in the absence of air(48) appears to be catalyzed by traces of the tertiary phosphine which is used to prepare the palladium dimerization catalyst. 

Another alternative method to produce sebacic acid iavolves a four-step process. First, butadiene [106-99-0] is oxycarbonylated to methyl pentadienoate which is then dimerized, usiag a palladium catalyst, to give a triply unsaturated dimethyl sebacate iatermediate. This unsaturated iatermediate is hydrogenated to dimethyl sebacate which can be hydrolyzed to sebacic acid. Small amounts of branched chain isomers are removed through solvent crystallizations giving sebacic acid purities of greater than 98% (66). 

At about the same time, a synthesis of leukotriene-A, also termed SRS-A ( slow reacting substance of anaphylaxis ), which made use of the Wittig olefmation was described77). The ylide of 100 is reacted with ethyl 5-formyl-2,4-pentadienoate 101 to give the ( , , Z, Z)- tetraenoic ester 102. Reduction and mesylation of 102, subsequent conversion into the sulfonium salt, and treatment of the latter with a base yields a sulfonium ylide which is reacted with methyl 4-formylbutanoate 69 to the epoxy-tetraenoic ester 103. After separation of the cis-epoxide by HPLC, 103 was treated with the S-trimethylsilyl derivative of glutathione dimethyl ester N-trifluoroacet-amide. The diastereomeric products thus obtained were separated by means of HPLC and hydrolyzed to 104 77) (Scheme 18). 

Conjugated dienes are a special substrate for the TMM synthon because they can potentially undergo [3 + 2] as well as [4 + 3] cycloaddition. While dimethyl ( . )-muconate gives only seven-membered ring [4 + 3] adducts, methyl 2,4-pentadienoate reacts exclusively at the terminal double bond with (79) to give a vinylmethylenecyclopropane (equation 100). The diphenyl system (81) also reacts with simple 1,3-dienes to produce only diphenylidenecyclopentanes in the presence of Ni or Pd catalysts (equation 101). ... 

In a very similar manner, tandem 1,6- and 1,4-additions of -dicarbonyl compounds to methyl 2,4-pentadienoate were utilized by Danishefsky and coworkers- foi the formation of several bi- and tricyclic ring systems. For example, reaction of the enolate of dimedone with this ester gave the expected 1,6-addition product protonation/deprotonation set the stage for a subsequent intramolecular 1,4-addition (equation 9). Likewise, a ketodiester was used to transform the pentadienoate in a one-pot procedure by consecutive 1,6- and 1,4-additions into a richly functionalized tricyclic product which was then converted into the natural product ( )-cpiclovane (equation 10). According to this principle, Irie and coworkers obtained several decalin-2,7-diones by treatment of 2-methylen-2-cyclohexenones with dimethyl 3-oxoglutarate. 

Dihydroxy-2,2-dimethyl-6-methylenecyclohexyl)-3-methyl-2,4-pentadienoic acid, D-30155... 

Dihydroxy-2,2-dimethyl-6-methylenecyclohexyl)-3-methyl-2,4-pentadienoic acid Me ester, in D-30155 1,6-Dihydroxy-3,11(13)-eudesmadien-12-oic acid Me ester, in D-30171 3-Hydroxy-6-methoxy-7( 11 )-eremophilen-12,8-olide, in D-30168... 

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... 

---