Merged mechanisms for hydride transfer from 1,4-dihydronicotinamides

Nucleophilie‐ und Elektrophilieskalen als Ordnungsprinzipien polarer organischer und metallorganischer Reaktionen

“…Die Tatsache, daß auch Hydridübertragungen (M-H-Spaltung) und Reaktionen von Metall-7i-Komplexen (C-M-Spaltung) diesen einfachen Beziehungen genügen, zeigt aber, daß dies keine unabdingbaren Voraussetzungen sind. Das Verhalten von Kom plexen aus Carbonylverbindungen und Lewis- [54, , doch wurde in neueren Arbei ten, vor allem bei acceptorsubstituierten Carbokationen, der Zusammenhang zwischen Elektrophilie und thermodynamischer Stabilität angezweifelt 1121] . Für zahlreiche Klassen präparativ wichtiger Elektrophile gibt es bisher keine quantitativen Reakti vitätsdaten, so daß die Bestimmung weiterer Elektrophilieparameter für die Weiterentwicklung dieses Gebietes vorrangige Be deutung hat.…”

Characterization of the Transition State for the Hydride Transfer in a Model of the Flavoprotein Reductase Class of Enzymes

“…Furthermore, even considering the hypothesis of a concerted one-step pathway, the coupling between the H motion and the electronic shift has to be kept in mind (12). The overall details on merged mechanisms for hydride transfer from 1,4-dihydronicotinamides can be found in a recent review by Bunting (13). Furthermore, a theoretical framework for the partial uncoupling of the electron transfer and hydrogen migration events can be nicely obtained from the valence-bond configuration mixing model developed by Shaik and Pross (14).…”

Using a Two-Step Hydride Transfer To Achieve 1,4-Reduction in the Catalytic Hydrogenation of an Acyl Pyridinium Cation

“…Multi-step mechanisms beginning with e − transfer have often been suggested as an alternative to the single-step transfer of hydride, particularly for H − transfers from NAD(P)H and its analogs 18 Scheme 1. shows a possible multi-step pathway, involving an H• transfer (HAT)19,20 after the initial single-electron transfer (SET);21,22 the possibility that the “H•” step involves the separate transfer of H + and e − has also been considered 22–25.…”