Carbonylation miscellaneous carbonylative processes

Miscellaneous. High-temperature and n.m.r. of [56 M = (Cp)Rh or Ma = (Cp)RhCu-H)Rh(Cp), X = CHaCHa M = (Cp)Rh, X = CHJ are consistent with one rearrangement process whereby only the metal-metal axis oscillates relative to the dienyl ring. The cyclopentadienyl signals, for instance, remain inequivalent at all temperatures. These results may be contrasted with those from similar iron complexes (56 M = Fe(CO)3, X = CHaCHg) where in the high-temperature limit all the carbonyls become equivalent. Thus at least one other... 

Several studies have investigated empirically the flux of chemicals within snow or between snow and the atmosphere (Guimbaud et al., 2002 Albert and Shultz, 2002 Herbert et al., 2006). In particular, measured concentration gradients within the atmospheric boundary layer or within the snow pack have been used to calculate a chemical s flux into or out of the snow pack. This approach has resulted in miscellaneous parameterizations to calculate fluxes of, for example, carbonyl compounds and NO c species from the snow pack as a result of photochemical processes in snow (Domind and Shepson, 2002 Hutterli et al., 1999 Guimbaud et al., 2002 Grannas et al., 2002). However, flux measurements can only be used to derive kinetic transport parameters, such as diffusivities and mass transport coefficients, if the chemicals involved are reasonably persistent and do not undergo rapid conversions within the snow pack. For example, measurements of the flux of carbonyl compounds out of snow are more likely to reflect the kinetics of formation in the snow pack than the kinetics of snow-air gas exchange. As a result, there is a very limited number of experimental studies that provide quantitative information on the rate of chemical transport in snow. 

This chapter covers organocatalytic processes where the enantio-determining step involves a proton transfer. Most of the organocatalytic processes outlined herein share a key step in common, i.e. the enantioselective protonation of an enolate or enol intermediate species obtained in situ from various precursors. The main organocatalytic approaches reported in the literature may be classified according to the nature of these precursors (Scheme 3.1). Special emphasis will be giveu to decarboxylation of malonates, addition of protic nucleophiles (NuH) to keteues or to a,P-unsaturated carbonyl compounds. We will also focus on tautomerisation of enols formed in situ via photodeconjugation of a,P-unsaturated esters and on the protonation of silyl enolates. Finally, a last section will be devoted to other miscellaneous substrates. 

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