Flow Rhodaelectro-Catalyzed Alkyne Annulations by Versatile C–H Activation: Mechanistic Support for Rhodium(III/IV)
摘要:
A flow-metallaelectro-catalyzed C-H activation was realized in terms of robust rhodaelectro-catalyzed alkyne annulations. To this end, a modular electro-flow cell with a porous graphite felt anode was designed to ensure efficient turnover. Thereby, a variety of C-H/N-H functionalizations proved amenable for alkyne annulations with high levels of regioselectivity and functional group tolerance, viable in both an inter- or intramolecular manner. The electro-flow C-H activation allowed easy scale up, while in-operando kinetic analysis was accomplished by online flow-NMR spectroscopy. Mechanistic studies suggest an oxidatively induced reductive elimination pathway on rhodium(III) in an electrocatalytic regime.
An efficient double C–N bond formation sequence to prepare highly substituted quinazolines utilizing benzimidates and dioxazolones under the catalytic redox-neutral [Cp*RhCl2]2/AgBF4 system, where dioxazolones could work as an internal oxidant to maintain the catalytic cycle, is reported. N-Unsubstituted imine not only acts as a directing group but also functions as a nucleophile in postcoupling cyclization
Synthesis of isoquinolines based on efficient C–C and C–N bond formation through Rh(III)-catalyzed C–H activation and subsequent intramolecular cyclization is reported. Diazodiesters serving as a C2 source in the newly formed heterocycles are first demonstrated. Additionally, the Rh(III)-catalyzed direct C–H activation/cyclization of benzimidates with diazoketoesters is also described.
Compounds of the formula I
in which X, Q, R1 and R2 have the meanings indicated in Claim 1, are inhibitors of pyruvate dehydrogenase kinase (PDHK), and can be employed, inter alia, for the treatment of diseases such as cancer.