Dienoates, conjugated

Lie and coworkers31 reported the synthesis and NMR properties of all geometrical isomers of conjugated linoleic acids. Pure geometric isomers of conjugated linoleic acid (CLA) were prepared from castor oil as the primary starting material. Methyl octadeca-9Z, 11 /i-dienoate (36) and methyl octadeca-9Z,llZ-dienoate (38) were obtained by zinc reduction of methyl santalbate (35, methyl octadec-11 -en-9-ynoatc) and methyl... 

In 1965, Danishefsky and Cunningham19 and Berchtold and coworkers20 simultaneously reported 1,6-addition reactions of enanimes to conjugated dienoates the zwitterionic intermediates cyclize spontaneously and eliminate an amine to furnish 1,3-cyclohexadienes... 

Isolated instances of 1,4-addition reactions of other hetero-nucleophiles to 4-en-2-ynoic acids and derivatives have been reported172-174. Thus, treatment of methyl 4-methyl-4-penten-2-ynoate with phenolate provided the 3-phenoxy-substituted conjugated dienoate (equation 71)172, and the 1,4-addition of water-soluble phosphines to 4-octen-2-ynoic acid afforded dienylphosphonium salts which were transformed into the corresponding phosphine oxides (equation 72)174. 

Materials. The catalyst, PdCl2 (Fisher Scientific, dry, purified grade) and Ph3P (Strem Chemicals) were used as purchased. Methyl linoleate, alkali-conjugated methyl linoleate (cis,trans-9,11- and 10,12-octadeca-dienoate), and methyl linolenate were prepared as before (21). 

The conjugate addition of organocopper reagents to polyalkenic carbonyl compounds presents an opportunity in which either 1,4-, 1,6- and sometimes 1,8-addition can occur. Much of the early woik in this area was conducted in the study of the reaction of a dienoate or dienone with an alkylcuprate or a catalytic copper/organomagnesium combination. The predominant mode of addition for the reaction of a dienoate and a copper-based organomagnesium reagent was found to be 1,6 not 1,4.72 If the opportunity of 1,8-addition was present, then this mode prevailed.73 However, a truly systematic study has not been carried out with the various reagents. 

Under GTP conditions conjugated dienoates as well as trienoates polymerize faster than methacrylates with anionic catalysis. The dienesilyl acetal 6a is a better initiator than MTS [16] (Scheme 6). 

A new role of iron catalyst in the Grignard conjugate addition has been disclosed.97 It catalysed 1,6-addition of aryl Grignard reagents to 2,4-dienoates or -dienamines in a highly regio- and stereo-selective manner. 

Garrido and coworkers116 have demonstrated the use of homochiral lithium (a-methyl-benzyljbenzylamide 175 to initiate the highly stereoselective conjugate addition-cyclization of dimethyl ( , )-octa-2,5-dienoate, 174, to generate the homochiral cyclopentane derivative (—)-(lR,2R,5R,aR)-176 with complete control over the configuration of C-l and C-2 and excellent control over C-5 (Scheme 54). 

Marshall and Ruden (196) have reported a conjugate addition of lithium dimethylcuprate to a cyclopropyl enone. The major products are the 1,4-adduct and one from a previously unreported 1,6-addition to the cyclopropyl ring [Eq. (96)]. 1,6-Conjugate additions are known for dienoates (206) and 2,2-di(carboxyethyl)vinylcyclopropane 94, cf. 59). 

A mercury-free route to allyl vinyl ethers that relies on the Michael addition of allyl alcohols to unsubstituted alkenyl sulfoxides, followed by thermal loss of sulfenic acid and concurrent Claisen rearrangement has been described [145]. This methodology has been applied to the synthesis of isocar-bacyclin [146]. Posner reported an acid-catalyzed protocol that produces conjugated dienoate esters from allylic alcohols and a sulfinyl orthoester [147]. Additionally, the use of propargyl alcoholates and a chloro alkenyl sulfox-... 

The formation of a titanium chelate enables regiochemical control of the conjugate addition of a thiol to an a,/3,y,d-dienone, as shown in Eq. (307) [694]. Simple base-catalyzed reaction occurred selectively at the terminal (d) position of the substrate. When, however, a similar reaction was performed in the presence of TiCU, addition occurred exclusively at the position / to the carbonyl group, where the intermediate can take the chelate form, as depicted. The same observation was also noted for the corresponding conjugated trienone. A similar reaction has been applied to the cis —> trans isomerization of conjugated dienoates [695]. 

Cis-trans means cis, trans conjugated dienoate trans-trans means trans, trans conjugated dienoate. 

Conjugate additions of divinylcuprates to ethyl propiolate joins two acetylenic units to furnish isomerically pure (2E, 4Z)-conjugated dienoates." ... 

Analogous substrate t-butyl ( )-hexa-2,4-dienoate was shown to undergo a highly diastereoselective conjugate addition with chiral lithium amides (e.g., N-benzyl-a-methylbenzylamide). Subsequent transformations of intermediate unsaturated aminoester, like iodolactonization or dihydroxy-lation, gave the expected daunosamine derivatives, although with very limited effectiveness [86]. 

Reaction of linoleate with toluene-4-sulfonic acid could conceivably be a method of hydrating one or both of the double bonds. In fact, the major products were the 9,12-and lOjlS-tetrahydrofiuans (44%) accompanied by the 9,13-tetrahydropyran (4%) and smaller amounts of isomeric tetrahydrofiuans (8,11-, 10,13-, and 11,14-) and tetrahydropyrans (8,12- and 10,14-) (Scheme 7). These compounds were readily identified by a combination of chromatographic and spectroscopic techniques (10). Similar products were obtained with the trans isomers of linoleate (but not with the conjugated 9,11- and 10,12-dienoates) and from several oxygenated monoene esters... 

Posner and colleagues have recently made use of a [3,3]-sigmatropic rearrangement of an a,P-unsaturated sulfoxide as part of a regiospecific conversion of allylic alcohols into two-carbon-extended conjugated dienoate esters [233]. For example, reaction of allyl alcohol (291) with the sulfinyl orthoester (292) and a catalytic amount of 2,46-trimethylbenzoic acid in dichloromethane at 100°C produced ethyl pentadienoate (295) in 75% yield. The reaction is believed to... 

De la Herran, G., Murcia, C. and Csdky, A.G. (2005) Rhodium-catalyzed reaction of aryl- and alkenylboronic acids with 2,4-dienoate esters conjugate addition and Heck reaction products. Org. Lett., 1, 5629-32. 

The reagent mixture can also reduce conjugated dienoates to 3,Y-... 

Adlof, R.O. (1997) Preparation of Methyl cis-9, trans-11- and trans-9, frara-ll-octadeca-dienoate-17,17,18,18-d4. Two of the Isomers of Conjugated Linoleic Acid, Chem. Phys. Lipids 88, 107-112. 

For several years now we have studied the inter- and intramolecular Michael reactions with allylsilanes. In light of the precedents mentioned above, we expected that allylsilanes would react in 1,6-fashion with polyethylenic electrophiles. However, we observed that the intermolecular condensation of trimethylallylsilane with conjugated dienoates and dienonitriles under fluoride ion catalysis afforded exclusively 1,4-adducts, while Lewis acid catalysis failed to promote reaction (Eq. 3) ... 

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