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Hydrogen-metal exchange

Similar reactions are available for the other alkali metals. Metalation (metal-hydrogen exchange) and metal addition to alkenes provide further routes, e.g. [Pg.102]

Synthesis by alkali-metal/hydrogen exchange in unsubstituted alkali-metal 9,10-phenanthreno-cyanines leads to metal-free products, e.g. 8. [Pg.798]

Alkali-metal/hydrogen exchange in an unsubstituted alkali-metal 1,6,10.15,19,24,28,33-oc-taaza-2,3-naphthalocyanine 1 provides the metal-free compound 2.458 462... [Pg.832]

As pointed out earlier (Sect. 7.1), alkyl lithium reagents induce metal-hydrogen exchange reactions. This possibility was investigated first by Paddock and coworkers [266,227]. They have found that the anion generated by the reaction of methylphosphazene with n-butyl lithium interacts with electrophiles such... [Pg.73]

V-Benzylthieno[3,2-6]pyrrole (18) was lithiated and upon treatment of the lithio derivative with methyl chloroformate, 2-methoxycarbonyl-lV-benzylthieno[3,2-f>]pyrrole (51) was obtained (Scheme 10). The a-proton in the thiophene ring is more reactive towards metal-hydrogen exchange compared to the proton at C-5. [Pg.1051]

There are three general types of metallation reactions (metal-hydrogen exchange) that are commonly used to synthesize organoalkali metal compoimds from organic molecules Direct reaction with an alkali metal, reaction with an alkali metal hydride, or reaction with an organo- or amido-alkali metal. Since these reactions involve acid/base equilibria, they are dependent on both the C-H acidity of the organic molecule and the basicity of the alkali metal source. [Pg.85]

A few years earlier, the kinetics of a much slower reaction (Scheme 30). the metal-hydrogen exchange reaction, was studied [84] gas evolution was followed over time for the lower alkylmagnesium halides in their reactions with 1-hexyne (Scheme 30). [Pg.242]

A side reaction may be metallation of hydrogens in positions ortho or a to the halogen. The fast rates of halogen-Li exchanges, especially in cold electron-donating solvents, enable low T to be used and the extent of the slower metallations to be minimized. The presence of tetramethylethylenediamine (TMED) however, can promote metallations more than metal-hydrogen exchanges . [Pg.137]

Metal-hydrogen exchange between organomagnesiums and hydrocarbons can be used to prepare new organomagnesiums ... [Pg.459]

Because organolithium reagents are powerful bases,28V the metal-hydrogen exchange reaction with functionalized substrates plays an important role in many syntheses.288 jhis acid-base reaction is believed to... [Pg.623]

H. Organolithium Reagents Metal-Hydrogen Exchange, -B uLi/(-) - sparteine... [Pg.627]

See other pages where Hydrogen-metal exchange is mentioned: [Pg.659]    [Pg.787]    [Pg.796]    [Pg.74]    [Pg.468]    [Pg.1051]    [Pg.659]    [Pg.72]    [Pg.254]    [Pg.151]    [Pg.302]    [Pg.278]    [Pg.659]    [Pg.277]    [Pg.276]    [Pg.277]    [Pg.370]    [Pg.277]    [Pg.122]    [Pg.19]    [Pg.122]    [Pg.462]    [Pg.489]    [Pg.490]    [Pg.202]    [Pg.70]    [Pg.301]    [Pg.584]    [Pg.608]    [Pg.623]    [Pg.625]    [Pg.626]    [Pg.686]   
See also in sourсe #XX -- [ Pg.811 ]

See also in sourсe #XX -- [ Pg.623 , Pg.624 , Pg.625 , Pg.626 , Pg.627 , Pg.628 , Pg.629 , Pg.630 , Pg.631 , Pg.632 ]

See also in sourсe #XX -- [ Pg.109 , Pg.125 ]



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