An organic–inorganic titanosilicate with an amine ligand shows high catalytic activity, selectivity and recyclability in alkene epoxidation.

In past decade, gold revealed more and more unique properties in carbene chemistry. It was disclosed in our recent communication (J. Am. Chem. Soc. 2014, 136, 6904) that gold carbenes have unprecedented chemo- and site-selectivity and ligand effect toward the functionalization of C–H bonds in phenols. In this full article, we report a comprehensively combined theoretical and experimental study on the mechanism of the insertion of gold carbenes into C–H and O–H bonds in phenol. It significantly revealed that the ligands have an important effect on C–H insertion and the reaction proceeds through a pathway involving the formation of an enolate-like intermediate. Moreover, two water molecules serving as a proton shuttle are believed to be the key issue for achieving chemoselective C–H functionalization, which is strongly supported by the DFT calculations and control experiments. It is the first time that a clear explanation is given about the prominent catalysis of gold carbenes toward C–H functionalization based on a theoretical and experimental study.

A highly enantioselective [2+2] versus a [4+2]-cycloaddition of 3-styrylindoles to N-allenamides catalyzed by identical gold(I)/chiral phosphoramidite complexes is presented, which provides facile access to synthetically valuable, optically active substituted cyclobutanes and tetrahydrocarbazoles. The cycloaddition mode unexpectedly depends on the electronic nature of the N-substituent 3-styrylindoles, the origin of which could be well rationalized using DFT calculations and experimental results. To the best of our knowledge, the present work represents the first example of such an impressive substituent effect in tuning the reaction mode with high chemo-, regio- and enantioselectivity in asymmetric gold catalysis.

Rh(II)-catalyzed multicomponent reaction achieved to give α-amino-β-indole ketones by trapping α-amino enols with vinylimine ions.