Comprehensive DFT calculations have been performed to pursue deeper understandings on the mechanism of Rh-catalyzed asymmetric dearomatization of 2-naphthols initiated with C–H activation, which was developed by our group recently. A refined reaction mechanism is described here to account for the experimentally observed high enantio- and regioselectivity. Although the C–H activation was suggested to be involved in the turnover-limiting step, the enantioselectivity of the reaction was found to be determined during the migratory insertion of the alkyne. Different from the originally proposed mechanism, the final dearomatized product is afforded via a [1,3′]-reductive elimination directly from the eight-membered rhodacyclic intermediate generated from the migratory insertion step. In addition, the π–π interaction between the phenyl substituent on the alkyne and 2-naphthol might partially contribute to the high regioselectivity when unsymmetrical alkynes were employed as the substrates.Keywords: asymmetric dearomatization; C−H activation; DFT calculation; enantioselectivity; reaction mechanism; Rh-catalysis

An Ir-catalyzed asymmetric synthesis of five-membered aza-spiroindolenines is achieved. Based on the detailed investigation of the reaction patterns of the aryl iminium migration, a one-pot asymmetric allylic dearomatization/migration sequence from racemic indole derivatives is realized, affording enantioenriched Pictet–Spengler-type products bearing an additional allylic stereogenic center adjacent to the C3 position of the indole core.

In this article we report a comprehensive density functional theory study on the Pd-catalyzed intermolecular asymmetric allylic dearomatization reactions of multisubstituted pyrroles. The calculated results are in line with the previous experimental observations (J. Am. Chem. Soc. 2014, 136, 6590), and the remarkable regio- and enantioselectivity are well explained. Of all the potential nucleophilic sites around the multisubstituted pyrrole ring, the reaction always occurs at the position where the HOMO of the molecule distributes most significantly. In contrast to the common view on the enantioselectivity of the Pd-catalyzed asymmetric allylic substitution reactions, we find that the steric interaction between the nucleophile and the chiral ligand does not have the dominating effect on the enantioselectivity of the reaction. Instead, the interaction between the allyl moiety and the incoming nucleophile plays an important role in the enantioselectivity-determining process.

We report herein an unprecedented direct catalytic C6 functionalization reaction of 2,3-disubstituted indoles with various N–Ts aziridines catalyzed by Sc(OTf)3 under mild conditions. Mechanistic studies revealed that a kinetically favored but reversible formal [3 + 2] annulation occurs initially. The direct C6 functionalization, although having a relatively higher energetic barrier, delivers the thermodynamically favorable products.

This paper describes a combined theoretical and experimental investigation into the acid-catalyzed migration of spiroindolenines to the corresponding fused cyclic products. It is suggested that the “three-center-two-electron”-type transition state is the crucial reason accounting for the highly stereoselective phenomenon. Further studies demonstrated that the electronic property of the migratory group as well as the ring size may have a major influence on the reaction profile of the migration process. Some predictions based on the computational results were supported by additional experiments.

An Ir-catalyzed asymmetric synthesis of five-membered aza-spiroindolenines is achieved. Based on the detailed investigation of the reaction patterns of the aryl iminium migration, a one-pot asymmetric allylic dearomatization/migration sequence from racemic indole derivatives is realized, affording enantioenriched Pictet–Spengler-type products bearing an additional allylic stereogenic center adjacent to the C3 position of the indole core.