Triflic Acid as an Efficient Brønsted Acid Promoter for the Umpolung of N-Ac Indoles in Hydroarylation Reactions
作者:Raj Kumar Nandi、Alejandro Perez-Luna、Didier Gori、Rodolphe Beaud、Régis Guillot、Cyrille Kouklovsky、Vincent Gandon、Guillaume Vincent
DOI:10.1002/adsc.201701074
日期:2018.1.4
We report that triflicacid, a strong Brønsted acid, is a very powerful alternative to FeCl3 to mediate the hydroarylation of N−Ac indoles, which delivers regioselectively 3‐arylindolines, 3,3‐spiroindolines or 2‐arylindolines. Mechanistic explorations point towards the existence of a highly electrophilic intermediate by simultaneous activation of the acetyl and of the C2=C3 bond by protons.
The puzzling hydroarylation of N-Ac indoles promoted by iron trichloride involves a doubly activated intermediate: as supported by the electron density topology of a crystal, IR monitoring, and DFT calculations.
FeCl<sub>3</sub>-Mediated Friedel-Crafts Hydroarylation with Electrophilic<i>N</i>-Acetyl Indoles for the Synthesis of Benzofuroindolines
作者:Rodolphe Beaud、Régis Guillot、Cyrille Kouklovsky、Guillaume Vincent
DOI:10.1002/anie.201206611
日期:2012.12.7
IRONic electrophilicindoles! The C3‐regioselectivehydroarylation of N‐acetyl indoles with aromatic nucleophiles mediated by FeCl3 features a rare example of the electrophilic reactivity of the indole core in a Friedel–Crafts reaction. This indole umpolung allows us straightforward access to the tetracyclic benzofuroindoline motif found in the natural product diazonamide A, which is a potent antitumor
The development of aerobic oxidative C–H/N–H cross-coupling catalyzed by the first-row transition metals is attractive yet challenging. Here, the first iron-catalyzed intramolecular cross-dehydrogenative coupling for the synthesis of carbazoles and indoles using air as the oxidant is reported. The general and efficient protocol allows for C–Nbondformation under green conditions with excellent functional