Exploring the Oxidative Cyclization of Substituted
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‐Aryl Enamines: Pd‐Catalyzed Formation of Indoles from Anilines
作者:Julia J. Neumann、Souvik Rakshit、Thomas Dröge、Sebastian Würtz、Frank Glorius
DOI:10.1002/chem.201100631
日期:2011.6.20
The direct Pd‐catalyzed oxidative coupling of twoCH‐bonds within N‐aryl‐enamines 1 allows the efficient formation of differently substituted indoles 2. In this cross‐dehydrogenative coupling, many different functional groups are tolerated and the starting material N‐aryl‐enamines 1 can be easily prepared in one step from commercially available anilines. In addition, the whole sequence can also be
strategy. The iron(II)-catalyzed domino isomerization of 3-alkyl/aryl-4-arylisoxazoles provides a selective access to a wide range of structurally diverse highly substituted indole-3-carboxylates. The operational simplicity, high atom efficiency, and the use of stable starting materials and an inexpensive and low-toxicity catalyst are some of the attractive features of this tandem double ring-opening–ring-closure
Multisubstituted indoles were synthesized via a one-pot tandem copper-catalyzed Ullmann-type C–N bond formation/intramolecular cross-dehydrogenativecoupling process at 130 °C in DMSO. The methodology allows practical and modular assembly of indoles in good to excellent yields from readily available aryl iodides and enamines.
one-pot sequence of N-alkylation, saponification and methoxyamidation, and final intramolecular oxidative C–N bond formation. The underpinning of the strategy entails Pd(OAc)2/Cu(OAc)2-mediated oxidative C(sp2)–C(sp2) bond formation and I(III)-mediated oxidative C(sp2)–N bond formation.