Phosphine-Catalyzed Crossed Rauhut-Currier-Type Coupling and [3 + 2]-Cycloaddition of 2-Alkylidene-3-oxindoles with Alkenes and Allenes to Access β,γ-Unsaturated Enones and Polycyclic Oxindoles.
Saikumar Banda, Lasse Johannßen, Alice Voss, Alexander Villinger, Gudrun Wenzel, Jens Holz, Malte Brasholz
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引用次数: 0
Abstract
Dihydroazepino[1,2-a]indole diones are tricyclic N-acyl-2-alkylidene-3-oxindole enones that readily engage in tertiary phosphine-catalyzed intermolecular coupling reactions with acceptor-substituted alkenes. In these reactions, the tricyclic α-substituted enones undergo an α-alkylation with concomitant formation of a quaternary stereocenter, as well as the installation of a new double bond within the seven-membered azepane ring. The organocatalytic reaction constitutes a special case of the crossed intermolecular Rauhut-Currier reaction as the presence of the α-substituent in the enones prohibits the formation of an α,β-unsaturated product, but instead, skipped β,γ-unsaturated enones are obtained. With allene carboxylates as alternative coupling partners, the crossed Rauhut-Currier-type reaction competes with a regioselective allene to enone [3 + 2]-cycloaddition, and the product selectivity can be controlled by the choice of the phosphine organocatalyst.
期刊介绍:
The Journal of Organic Chemistry welcomes original contributions of fundamental research in all branches of the theory and practice of organic chemistry. In selecting manuscripts for publication, the editors place emphasis on the quality and novelty of the work, as well as the breadth of interest to the organic chemistry community.