Organozinc compounds, hydrogenation

Results of the polymerization of propylene oxide by these four kinds of organometallic compounds showed that the zinc compounds are superior to the aluminum compounds with respect to their stereoregulating power. It is noteworthy that the zinc catalyst is generally superior to the aluminum catalyst as the stereospedfic polymerization catalyst. Among the two organozinc compounds, EtZnNBu ZnEt was thought to be more suitable than EtZnNHBu for detailed studies, because the former was monomeric and had no reactive hydrogen atom. 

We have shown for the first time 12 that not only c/oso-carboranes, but also iodo-nido-7,8-dicarbaundecaborates containing an iodine atom in the polyhedral skeleton or in the pentagonal plane of the polyhedron enter into cross-coupling reactions with organomagnesium and organozinc compounds catalyzed by palladium complexes. It is known that ifo-7,8-dicarbaundecaborates are strong BH-acids (pKa = 21.1), due to the presence of the axial hydrogen atom. 

Water as the Co-)Solvent. In view of the reactivity of organozinc compounds towards acidic hydrogens, the use of water as the (co-)solvent in Zn-Barbier reactions is even more surprising than the use of alcohols. 

Organometallic compounds asymmetric catalysis, 11, 255 chiral auxiliaries, 266 enantioselectivity, 255 see also specific compounds Organozinc chemistry, 260 amino alcohols, 261, 355 chirality amplification, 273 efficiency origins, 273 ligand acceleration, 260 molecular structures, 276 reaction mechanism, 269 transition state models, 264 turnover-limiting step, 271 Orthohydroxylation, naphthol, 230 Osmium, olefin dihydroxylation, 150 Oxametallacycle intermediates, 150, 152 Oxazaborolidines, 134 Oxazoline, 356 Oxidation amines, 155 olefins, 137, 150 reduction, 5 sulfides, 155 Oxidative addition, 5 amine isomerization, 111 hydrogen molecule, 16 Oxidative dimerization, chiral phenols, 287 Oximes, borane reduction, 135 Oxindole alkylation, 338 Oxiranes, enantioselective synthesis, 137, 289, 326, 333, 349, 361 Oxonium polymerization, 332 Oxo process, 162 Oxovanadium complexes, 220 Oxygenation, C—H bonds, 149... 

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