In the presence of a Brønsted acid catalyst, both aldehydes and N-Boc-aminals were converted to enecarbamates and N-Boc-iminium salts as activated nucleophiles and electrophiles, respectively, giving unprecedented Mannich adducts. The asymmetric variant of the present Mannich reaction has also been demonstrated with a chiral phosphoric acid catalyst.

A silica-monolayer loaded on alumina with weak Brønsted acid sites and large pore size can selectively dealkylate alkyl polycyclic aromatics to long-chain alkanes for production of chemicals fuel.

An efficient methodology for the synthesis of a series of new fused polyclyclic indoles has been developed by Brønsted acid-catalyzed intramolecular Friedel-Crafts reactions of properly designed indolyl alcohols.

o-Benzenedisulfonimide, a new strong bench-stable Brønsted acid, has been shown to efficiently catalyze the Mukaiyama aldol reaction of aldehydes or dimethyl acetals with silyl enol ethers under mild solvent-free reaction conditions.

Consecutive hydroamination/asymmetric transfer hydrogenation under relay catalysis of an achiral gold complex/chiral Brønsted acid binary system has been described for the direct transformation of 2-(2-propynyl)aniline derivatives into tetrahydroquinolines with high enantiomeric purity.

A new chiral Brønsted acid-catalyzed aza-Diels-Alder reaction of cyclic C-acylimines with cyclopentadiene has been developed. The reaction provides optically active aza-tetracycles in good yields with high diastereo- and enantioselectivities under mild reaction conditions.

An enantioselective cooperative process involving the concerted/simultaneous action of three different catalysts i.e. Au(I)/amine/chiral Brønsted acid catalysts has been realized for the synthesis of 2-substituted tetrahydroquinolines from 2-aminobenzaldehydes and terminal alkynes.

The interplay between metals and N-heterocyclic carbenes (NHCs) has provided a window of opportunities for the development of novel catalytic strategies within the past few years. The recent successful combination of Brønsted acids with NHCs has added a new dimension to the field of cooperative catalysis, enabling the stereoselective synthesis of functionalized pyrrolidin-2-ones as valuable sca...