Dataset Information

Photoredox Catalysis Unlocks Single-Electron Elementary Steps in Transition Metal Catalyzed Cross-Coupling.

ABSTRACT: Since initial reports, cross-coupling technologies employing photoredox catalysts to access novel reactivity have developed with increasing pace. In this Outlook, prominent examples from the recent literature are organized on the basis of the elementary transformation enabled by photoredox catalysis and are discussed in the context of relevant historical precedent in stoichiometric organometallic chemistry. This treatment allows mechanistic similarities inherent to odd-electron transition metal reactivity to be generalized to a set of lessons for future reaction development.

SUBMITTER: Levin MD

PROVIDER: S-EPMC4882737 | biostudies-other | 2016 May

REPOSITORIES: biostudies-other

ACCESS DATA

Similar Datasets

Project description:Detailed mechanistic studies on the coupling of aryl halides with thiols catalyzed by palladium complexes of the alkylbisphosphine ligand CyPF-(t)Bu (1-dicyclohexylphosphino-2-di-tert-butylphosphinoethylferrocene) are reported. The elementary steps that constitute the catalytic cycle, i.e. oxidative addition, transmetalation and reductive elimination, have been studied, and their relative rates are reported. Each of the steps of the catalytic process occurs at temperatures that are much lower than those required for the reactions catalyzed by a combination of palladium precursors and CyPF-(t)Bu. To explain these differences in rates between the catalytic and stoichiometric reactions, studies were conducted to identify the resting state of the catalyst of the reactions catalyzed by a combination of Pd(OAc)(2) and CyPF-(t)Bu, a combination of Pd(dba)(2) and CyPF-(t)Bu, or the likely intermediate Pd(CyPF-(t)Bu)(Ar)(Br). These data show that the major palladium complex in each case lies off of the catalytic cycle. The resting state of the reactions catalyzed by Pd(OAc)(2) and CyPF-(t)Bu was the palladium bis-thiolate complex [Pd(CyPF-(t)Bu)(SR)(2)] (R = alkyl or aryl). The resting state in reactions catalyzed by Pd(2)(dba)(3) and CyPF-(t)Bu was the binuclear complex [Pd(CyPF-(t)Bu)](2)(mu(2),eta(2)-dba) (9). The resting states of reactions of both aromatic and aliphatic thiols catalyzed by [Pd(CyPF-(t)Bu)(p-tolyl)(Br)] (3a) were the hydridopalladium thiolate complexes [Pd(CyPF-(t)Bu)(H)(SR)] (R= alkyl and aryl). All these palladium species have been prepared independently, and the mechanisms by which they enter the catalytic cycle have been examined in detail. These features of the reaction catalyzed by palladium and CyPF-(t)Bu have been compared with those of reactions catalyzed by the alkylbisphosphine DiPPF and Pd(OAc)(2) or Pd(dba)(2). Our data indicate that the resting states of these reactions are similar to each other and that our mechanistic conclusions about reactions catalyzed by palladium and CyPF-(t)Bu can be extrapolated to reactions catalyzed by complexes of other electron-rich bisphosphines.

Dataset Information

Photoredox Catalysis Unlocks Single-Electron Elementary Steps in Transition Metal Catalyzed Cross-Coupling.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure