Dienes hydration

Reaction of myrcene and sulfur dioxide under pressure produces myrcene sulfone. This adduct is stable under ordinary temperatures and provides a way to stabilize the conjugated diene system in order to hydrate it with sulfuric acid. The myrcene sulfone hydrate produced is pyrolyzed in the vapor phase in order to regenerate the diene system to produce myrcenol [543-39-5] (50). 

Lubineau and coworkers [18] have shown that glyoxal 8 (Ri = R2 = H), glyoxylic acid 8 (Ri = H, R2 = OH), pyruvic acid 8 (Ri = Me, R2 = OH) and pyruvaldehyde 8 (Ri = H, R2 = Me) give Diels-Alder reactions in water with poor reactive dienes, although these dienophiles are, for the most part, in the hydrated form. Scheme 6.6 illustrates the reactions with (E)-1,3-dimethyl-butadiene. The reaction yields are generally good and the ratio of adducts 9 and 10 reflects the thermodynamic control of the reaction. In organic solvent, the reaction is kinetically controlled and the diastereoselectivity is reversed. 

Several cationic palladium(II) aqua complexes, [Pd(H20)4], cis-[PdL(H20)2] (L = en, methionine methyl ester, l,5-dithiacycloocta-3-ol), and [Pd(dien)(H20)], serve as the active catalyst for the selective hydration of various nitriles to the corresponding carboxamides, e.g., CHCI2CN was hydrated to CHCl2C(0)NH2 in the presence of... 

Among other addition reactions dienes undergo catalytic hydrogeneration (1,2- and 1,4-), epoxidation (1,2- only, and more slowly than the corresponding simple alkenes), but they seldom undergo hydration. 

The presence of the C15 saturated chain displayed an efficient gelling ability in a wide range of organic solvents, water, and protic solvent mixtures (1 1), whereas the unsaturated derivatives (mixture of four molecules) formed fibrous nanostructures as opposed to stronger gels. The diene and triene components of the cardanyl glycosides in their fully hydrated state formed fluid nanostructures at room temperature and could not self-assemble to form gels. 

The first hydration step was promoted by Bronsted acids containing weakly or noncoordinating anions. In the second step, an intramolecular hydrogen transfer in the secondary alcohol was catalyzed by ruthenium(III) salts with chelating bipyridyl-type ligands. The possible complexation of the latter with the diene did not inhibit its catalytic activity in the allylic rearrangements, under acid-catalyzed hydration conditions. 

The addition of carboxylic acids to bicyclo[2.2.1]hepta-2,5-diene has been described by several authors the method described here is a modification of these procedures. Nortricyclanol has been prepared by the hydration of bicyclo[2.2.1]hepta-2,5-diene and the solvolysis of nortricyclyl and bicyclo[2.2.1]hept-2-en-5-yl halides, as well as by the saponification and... 

For a decade or so [CoH(CN)5] was another acclaimed catalyst for the selective hydrogenation of dienes to monoenes [2] and due to the exclusive solubility of this cobalt complex in water the studies were made either in biphasic systems or in homogeneous aqueous solutions using water soluble substrates, such as salts of sorbic add (2,4-hexadienoic acid). In the late nineteen-sixties olefin-metal and alkyl-metal complexes were observed in hydrogenation and hydration reactions of olefins and acetylenes with simple Rii(III)- and Ru(II)-chloride salts in aqueous hydrochloric acid [3,4]. No significance, however, was attributed to the water-solubility of these catalysts, and a new impetus had to come to trigger research specifically into water soluble organometallic catalysts. 

More synthetic interest is generated by the potentially very useful hydration of dienes. As shown on Scheme 9.6, methylethylketone (MEK) can be produced from the relatively cheap and easily available 1,3-butadiene with combined catalysis by an acid and a transition metal catalyst. Ruthenium complexes of several N-N chelating Hgands (mostly of the phenanthroline and bipyridine type) were found active for this transformation in the presence of Bronsted acids with weakly coordinating anions, typically p-toluenesulfonic acid, TsOH [18,19]. In favourable cases 90 % yield of MEK, based on butadiene, could be obtained. 

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