Hydrogenation hydroboration

Hydrogenation of olefins, enols, or enamines with chiral tVilkinson type catalysts, e.g., Noyort hydrogenation. Hydroboration of olefins with chiral boranes. Sharpless epoxi-dation of allylic alcohols. 

There are other stereospecific olefin addition processes which occur with cis or syn stereochemistry. Common examples include catalytic hydrogenation, hydroboration/oxidation, and dihydroxylation using osmium tetroxide. The stereospecificity of these syn additions requires that die facial properties of the olefinic bond be maintained throughout die addition process and that both new bonds are formed to the same face of the olefin. This is normally accomplished by a concerted syn addition to the n system. 

Bicyclo[4,l,0]heptanes.—The hydrogenation, hydroboration, thermolysis, amination, oxidation, and photochemical isomerization of various carane derivatives has been reviewed by Cocker. Another case of the repetition of earlier work has appeared, this time concerning the catalytic reduction of car-3-ene (307). Further work on the acid- and base-catalysed ring-opening of carene epoxides is reported (Scheme 17). ... 

In general, the acetylenic triple bond is highly reactive toward hydrogenation, hydroboration, and hydration in the presence of acid catalyst. Protection of a triple bond in disubstituted acetylenic compounds is possible by complex formation with octacarbonyl dicobalt [Co2(CO)g Eq. (64) 163]. The cobalt complex that forms at ordinary temperatures is stable to reduction reactions (diborane, diimides, Grignards) and to high-temperature catalytic reactions with carbon dioxide. Regeneration of the triple bond is accomplished with ferric nitrate [164], ammonium ceric nitrate [165] or trimethylamine oxide [166]. 

While the highly versatile rare-earth metal-catalyzed hydrogenation, hydroboration, hydrosilylation, hydroamination, and hydrophosphination has been studied over the last two decades, the rare-earth metal-mediated activation of the hydroxyl 0-H bond for an analogous hydroalkoxylation process [87,190] has been reported only recently. Homoleptic trisamides were reported to catalyze the smooth cyclization of allenyl alcohols [191] and alkynyl alcohols [191,192] to form the corresponding unsaturated ethers. 

Structure elucidation of 5-lactaranolides other relevant chemical transformations involved the conversion of the lactone into the furan ring and addition reactions to double bonds (hydrogenation, hydroboration, epo-xidation, osmylation). A brief account of these reactions will be included in the chapter on chemical conversions of Lactarius sesquiterpenes. 

Other syntheses of alkenyl halides have been pubhshed over the last decade using different approaches such as selective hydrogenation, hydroboration/protonolysis, metal-catalyzed addition, and E2 elimination just to name a few. 

The ergoline structure can be easily modified in these positions via addition reactions to A or A double bond. Hydrogenation, hydroboration, addition of mercury(II) salts in methanol and photochemically initiated addition of water or alcohols can therefore be found in older literature. The industrially used photochemical methoxylation of methyl lysergate and lysergol is discussed in Chapter 13. 

Various reactions have been carried out on the compounds Fp(CH2)/ GH=CH2 (m = Z or 3) including hydrogenation, hydroboration, and hydroformylation. Some of these reactions lead to functionalized Fp-alkyl compounds. 

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