Reduction of olefinic double bonds

The complete reduction of coal proceeds from aromatic rings through rings containing olefinic double bonds to saturated compounds. While reduction of the benzene ring takes place at a current efficiency of about 80% (8), current efficiency for reducing an olefin (1-decene) is only 27% as shown in this paper. The slow step in the coal reduction may very well be reduction of olefinic double bonds. An increase in the rate of olefinic double bond reduction may therefore lead to a considerable increase in current efficiency. 

U. Kazmaier, J. M. Brown, A. Pfaltz, P. K. Matzinger, H. G. W. Leuenberger, Formation of C-H Bonds by Reduction of Olefinic Double Bonds Hydrogenation, in Methoden Org. Chem. (Houben-Weyl) 4th ed. 1952-, Stereoselective Synthesis (G. Helmchen, R. W. Hoffmann, J. Mulzer, E. Schaumann, Eds.), Vol. E21d, 4239, Georg Thieme Verlag, Stuttgart, 1995. 

M. Zaidlewicz, Formation of C—H Bonds by Reduction of Olefinic Double Bonds—Hydroboration and Hydroalumination, in Methoden Org. Chem. (Houben-Weyl) 4th ed. 1952-, Stere-... 

The catalyst [CoH(CN)5] is soluble in water. It is selective for the reduction of olefinic double bonds in a,y9-unsaturated systems. Reduction of NO2 groups only occurs at elevated pressures. Hydrogenolysis of C-Hal bonds is observed [20]. Progress as far as water-soluble hydrogenation catalysts is concerned has also been made with Wilkinson-type catalysts by using phosphine ligands with sulfonic acid substituents [44]. 

Formation of C-H Bonds by Reduction of Olefinic Double Bonds via Hydroboration and Hydroalumination... 

The electrochemical reduction of activated double bonds may also be used in the characterization of olefins. In all cases in which pairs (124 and 125) of 1,2-disubstituted olefins in which both X and Y are electron-withdrawing... 

When the reduction of the double bond in the olefination product is carried out using H2 and Pd/C, 1-alkylated-l,4-diketone is obtained in good yield (Eq. 7.129).175... 

To complete the synthesis of brevicomin, the side-chain had to be deoxygenated. This could be achieved by a reduction of the keto group, eUmination of the resulting diol to the olefin and reduction of the double bond. 

Reduction. Successful asymmetric hydrogenations of olefin double bonds mediated by chiral phosphines have been reported (16) and the factors crucial for effective asymmetric induction in related systems have been discussed (17, 18). These reductions require functionality proximate to the double bond for any degree of success. 

In other solvents (ether, cyclohexane, acetone), the cycloaddition does not take place, only reduction of the double bond is observed. As regards the two monooxiranes of ewdo-bicyclopentadiene, in the course of acetone-sensitized photolysis only enrio-4-oxatetracycloundec-9-ene 136 is changed. Photoreduction of the double bond proceeds by a free-radical mechanism there is no interaction between the triplet-state excited olefin and the oxirane part. ... 

Another popular olefination-reduction sequence starts with commercially available ketone 122, transformed into olefin 123 using a Wittig or Wittig-Horner reaction [103] (illustrated in Scheme 11.32). Reduction of the double bond proceeds with high stereocontrol to yield the alio derivative 124. The cis arrangement at C2-C3 allowed formation of lactone 125 and the synthesis of avenaciolide 126 [104,105]. 

Isomerization of allylic sulfones and reduction of conjugated double bonds (Eq. 62), are possible disadvantages of the use of Mg as an electron-transfer agent.117 The occurrence of Julia olefination of 1,2-disulfone derivatives is another important drawback when performing reductive desulfonylation on these kinds of substrates (Eq. 63).118... 

A major drawback when reducing alkenyl sulfones with Na/Hg is that the configuration of the double bond is not necessarily preserved. Additionally, reduction of the double bond is occasionally observed as shown in Eq. 84, where a Julia-Lythgoe olefination process is also taking place.135... 

Selective reduction of both double bonds in a,jS-unsaturated carbonyl compounds that also contain an isolated olefin is possible with appropriate catalyst and reaction conditions . Chlorotris(biphenylphosphine)rhodium hydrogenates the isolated double bond. Thus, carvone, 13, is reduced to dihydrocarvone, 14, with careful measure of the uptake of Hj ... 

Reduction of the double bond in an olefinic aliphatic nitro derivatives is usually easy. The olefin linkage may be preserved only in aromatic nitro compounds [equation (j)] , or in particular structures such as hydroxycoumarins or pyranones . 

When the usual dehalogenating agents are applied to dihalides in which the halogen is flanked by a carbonyl group, they cause reduction of the double bond or resinification. However, such compounds are converted into olefins readily and in good yield by treatment with an equivalent amount of a trialkyl phosphite 72... 

The antihistiminic drug triprolidine consists of a substituted olefin and undergoes a two electron reduction of the double bond in a... 

Evidence for conjugate reduction as a key step in monot-erpene biosynthesis has been obtained from studies of the oxygenated monoterpenes of Mentha piperita (Fig. 19.10) (Croteau, 1984). The pathway from isopiperitenone to the menthol esters was deduced largely by time-course studies and direct feeding experiments. Other evidence supports the intermediacy of /-limonene (11) as the first cyclization product of GPP in this plant. This is followed by the adlylic oxidation of the olefin and subsequent isomerization and reduction of the double bonds of isopiperitenone to the men-thones (such as 26). Furthermore, stereospecific dehydrogenases responsible for the synthesis of /-menthol (27) and d-neomenthol (28) have been isolated (Croteau, 1984). 

Sodium borohydride is a useful reagent for replacing halogen by hydrogen in fluoro-olefins. It has now been found that in the presence of water, ethanol, or t-butanol in bis-(2-methoxyethyl) ether, it may cause reduction of the double bond, e.g ... 

DMF, 1 atm. H2, 3 h) , and 1 1 ( H2, Pd/CaCOa, benzene r.t., 1 h) (Figure 4.44). Alternatively, for allylic alcohol derivatives steric blocking of the hydroxy group can be used to slow the reduction of the double bond. Thus with 152, the olefinic bond was reduced in competition with the aryl iodo substituent ( H2,10% Pd/C, Et20 or EtOH, 11-13 equiv. EtaN) even at short reaction times, but in 153 it was reduced only to the extent of 3% or less in reactions of 3 h duration, regardless of the substitution at the phenolic hydroxyl ". ... 

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