Deuteration of olefins

This process accounts for most of the observations relating to product stereochemistry, double bond isomerism, deuterium exchange and other features encountered in the hydrogenation and deuteration of olefins. 140-142,144 addition of hydrogen to the double bond proceeds in... 

A very significant recent development in the field of catalytic hydrogenation has been the discovery that certain transition metal coordination complexes catalyze the hydrogenation of olefinic and acetylenic bonds in homogeneous solution.Of these catalysts tris-(triphenylphosphine)-chloror-hodium (131) has been studied most extensively.The mechanism of the deuteration of olefins with this catalyst is indicated by the following scheme (131 -> 135) ... 

A similar mechanism was proposed6103 b to account for the observed regio-specific deuteration of olefins coordinated to Pt(II). However, an electrophilic substitution mechanism without invoking a Pt(IV) adduct also seems reasonable. 

Deuteration of olefins.15 Deuterium adds specifically across the double bond of n-monoolefins when this homogeneous catalyst is used. In contrast, use of a heterogeneous catalyst such as platinum black leads to unspecific labeling. 

Two serious drawbacks of this method are the extensive deuterium scrambling around the reaction site and the occasional formation of olefinic side products, which are hard to separate by conventional means. The extent of olefin formation may depend on the nature of the Raney nickel since it is known that desulfurization with deactivated Raney nickel can yield olefins. Best results are obtained when the deuterated Raney nickel is prepared very rapidly and used immediately after preparation. 

A concerted four-center cis addition leads to (52) and a trans adduct a trans addition, possibly via protonium species, leads to (53) and a cis adduct a stepwise cationic addition leads to (54) and a mixture of cis and trans adducts. Recent studies by Marshall and Wurth strongly indicate that intermediate (54) is correct. Irradiation of octalin (55) in aqueous /-butyl alcohol (DaO)-xylene results in formation of the equatorially deuterated alcohols (56) and (57) and the equatorially deuterated exocyclic olefin (58) ... 

Many research groups have attributed the isomerization to a series of additions and eliminations of a cobalt carbonyl hydride. However, it has been shown that aldehydes may be found with formyl groups attached to a carbon atom other than the two of the double bond even under non-isomerizing conditions. Piacenti and co-workers (44, 45) studied the hydroformylation of [l-14C]propylene and of a>-deuterated a-olefins. Even for a-olefins with chain lengths up to C6, the formyl group was attached to all possible carbon atoms in the product mixture. However, in the deuterated experiments, deuterium was present only on carbons 2, 3, and a) of the resulting aldehydes. These results were explained by pro-... 

Interestingly, Cp Ir(NHC) complexes were also shown to be efficient catalysts for the deuteration of organic molecules using CD3OH or (CD3)2CO as deuterium sources (Scheme 3.17). A wide set of organic molecules (including ketones, alcohols, olefins and ethers) were deuterated in high yields [15]. 

A semi-quantitative treatment based upon the observation that, in the reactions of olefins with deuterium, the yields of deuterated paraffins often decrease logarithmically with increasing deuterium content, that is... 

Allylic terpenic thiols were prepared in 70-80% yield by this procedure. The reversibility under mild conditions of the ene reaction with N-sulfinylsulfonamides RS02N=S=0 had been exploited in allylic deuteration and tritiation of olefins [516]. 

Dehydration of hetisine diacetate (126) with phosphorus oxychloride and pyridine followed by basic hydrolysis afforded a mixture of olefins 136 and 137, whose structures were analyzed by H-NMR spectroscopy. These olefins can only be derived from hetisine diacetate if its structure is 126, a fact requiring the structure of hetisinone to be 128. Furthermore, hetisinone is stable to bases, behavior that is consistent with the assigned structure but less likely for either of the alternative /J-ketoalcohols 134 and 135. When hetisinone was heated in D2O-CFI3OD containing sodium deuteroxide, a mixture of deuterated hetisinones was obtained. Mass spectral analysis revealed the presence of 14% d, 53% d2, 24% d3, and 6% dA species. These data further confirmed that hetisinone is correctly represented as 128. 

Olefin metathesis has become one of the most important large-scale technical processes for the manufacture of olefins in the petrochemical industry [123]. When cyclic olefins are used as substrates, high-molecular polymers, which are formed by the so-called ring-opening metathesis (ROM), have found applications as elastomers and plastics. Gas-phase studies on the mechanism of olefin metathesis had been confined to simple metal carbenes, for example [Mn=CH2]+, [Fe=CH2]+,and [Co=CH2]+ [124-127]. Most of the metatheses have been observed with deuterated ethylene. 

The complex is an extremely active hydrogenation catalyst for terminal olefins 1 it is much less effective for the isomerization of olefins.1 Treatment of the complex with D2 results in the deuteration of the ortho-phenyl positions of the phosphine ligands14 as well as the Ru—D bond.1,4 It also serves as a catalyst for the preparation of selectively orf/fo-phenyl-deuter-ated triphenylphosphine.4... 

Hydrogenation of olefins on a soluble catalyst has been reported recently [61,62]. Tris(triphenylphosphine)rhodium chloride [(Ph3P)3RhCl] will promote homogeneous hydrogenation of reactive double bonds, including the A -bond in Ai -dien"3-ones, where the product of deuteration was the ia,2a-dideutero-compound (17) [62]. The mechanism is not... 

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