Enantioselective C-H bond functionalization of aromatic ketones with 1,6-enynes via photoredox/cobalt dual catalysis.

An enantioselective ortho-C(sp2)-H functionalization of ketones with 1,6-enynes is demonstrated via photoredox/cobalt dual catalysis. The method exhibits high yields, functional group tolerance, and selectivity. Mechanistic studies suggested the operation of visible-light mediated low-valent cobalt complex generation, intramolecular cyclization, ortho-C-H bond insertion, and reductive elimination as the key mechanistic steps.

Deaminative Olefination of Methyl N-Heteroarenes by an Amine Oxidase Inspired Catalyst.

We explored the bioinspired o-quinone cofactor catalyzed aerobic primary amine dehydrogenation for a cascade olefination reaction with nine different methyl N-heteroarenes, including pyrimidines, pyrazines, pyridines, quinolines, quinoxolines, benzimidazoles, benzoxazoles, benzthiazoles, and triazines. An o-quinone catalyst phd (1,10-phenanthroline-5,6-dione) combined with a Brønsted acid catalyzed the reaction. N-Heteroaryl stilbenoids were synthesized in high yields and (E)-selectivities under mild conditions using oxygen (1 atm) as the sole oxidant without needing transition-metal salt, ligand, stoichiometric base, or oxidant.

Boron-Catalyzed N-Alkylation of Arylamines and Arylamides with Benzylic Alcohols.

A sustainable boron-based catalytic approach for chemoselective N-alkylation of primary and secondary aromatic amines and amides with primary, secondary, and tertiary benzylic alcohols has been presented. The metal-free protocol operates at low catalyst loading, tolerates several functional groups, and generates H2O as the sole byproduct. Preliminary mechanistic studies were performed to demonstrate the crucial role of boron catalyst for the activation of the intermediate dibenzyl ether and to identify the rate-determining step.

Manganese-Catalyzed Divergent Markovnikov Addition and [2+2+2] Cycloaddition of 2-Carbonyl Indanone with Terminal Alkyne.

Herein, we report on manganese-catalyzed regioselective Markovnikov addition and [2+2+2] cycloaddition of 2-carbonyl indanones with terminal alkynes. This method provides an efficient approach for the construction of all-carbon quaternary centers and complex polycyclic hydrocarbon frameworks by the formation of new carbon-carbon single bonds in a regio- and stereoselective manner. Preliminary mechanistic experiments involving deuterium labeling, kinetic, catalytic, and stoichiometric reactions with plausible intermediates were performed to shed light on the reaction mechanism.