Heteroatoms, hydrogenation

Table 1.1 Carbon-Hydrogen and Heteroatom-Hydrogen Bond Dissociation Energies (D in kJ morI)a °...

In Table 2.4, we have collected background information for discussion in the following chapters. Recommended C—H bond dissociation enthalpies of selected organic compounds are reported in the first two columns, followed by a variety of heteroatom-hydrogen bond strengths including N—H, O—H, S—H, Ge—H, and Sn—H bonds. 

The effects of heteroatoms on autoxidation reactions are reviewed and discussed in terms of six phenomena (1) the effect on reactivity of a-hydrogens in the hydroperoxide chain mechanism in terms of electron supply and withdrawal (2) the effect on a-hydrogen acidity in base-catalyzed oxidation (3) the effect on radical ion stability in base-catalyzed redox chains (4) the possibility of heteroatom hydrogen bond attack and subsequent reactions of the resulting heteroradical (5) the possibility of radical attack on higher row elements via valence expansion (6) the possibility of radical addition to electron-deficient II and III group... 

P-Elimination of a hetero-substituted C-C single bond. The best-known reactions of this type are the heteroatom -heteroatom (Het -Het ) elimination (Het = O, Hal, S,...), heteroatom -hydrogen (Het -H ) elimination, Peterson olefination, Tschugajew reaction and Corey-Winter olefination. 

Alonso, F., Beletskaya, I. P., Yus, M. Transition-Metal-Catalyzed Addition of Heteroatom-Hydrogen Bonds to Alkynes. Chem. Rev. 2004, 104, 3079-3159. 

Transition metal-catalyzed addition of heteroatom-hydrogen bonds to alkynes in syntheses of cyclic amines and pyrroles by hydroamination reactions, in syntheses of O-heterocycles by hydroalkoxylation of alkynes, and in syntheses of S- and Se-heterocycles 04CRV3079. 

Scheme 56. Heterocyclization of C—C Unsaturated Compounds Having a Heteroatom—Hydrogen Bond...

Rhodium(II) compounds have become the premier choice in catalytic transformation of a-diazo compounds to induce cyclopropanation, aliphatic carbon-hydrogen bond insertion, heteroatom hydrogen bond insertion, aromatic substitution, and ylide formation. 

In contrast to the diverse chemistry of allylpalladium complexes, vinylpalladium intermediates have been involved mainly in the vinylpalladation of carbon-carbon unsaturated systems and in the insertion into carbon-hydrogen and heteroatom-hydrogen bonds (Scheme 10). It is found that a vinylpalladium species reacts with carbon electrophiles such as aldehydes, ketones, and nitriles (Scheme 11, type a). Oxidative addition of vinyl-halogen and -pseudohalogen bonds to Pd(0) is the common way to generate the vinylpalladium species. Vinyl-... 

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