Selective Para-C-H Alkynylation of Aniline Derivatives by Pd/S,O-Ligand Catalysis.

Herein, we report a nondirected para-selective C-H alkynylation of aniline derivatives by a Pd/S,O-ligand-based catalyst. The reaction proceeds under mild conditions and is compatible with a variety of substituted anilines. The scalability and further derivatizations of the alkynylated products have been also demonstrated.

Divergent Total Syntheses of Yaequinolone-Related Natural Products by Late-Stage C-H Olefination.

Divergent total syntheses of 10 yaequinolone-related natural products have been achieved for the first time by late-stage C-H olefination of 3,4-dioxygenated 4-aryl-5-hydroxyquinolin-2(1H)-ones, core structures of this family of natural products. A robust synthetic methodology to construct the core structures has been established, and the C-H olefination reaction has been carried out with synthetically useful yields and high levels of site-selectivity under mild reaction conditions in the presence of a Pd/S,O-ligand catalyst.

Selective C-H Olefination of Indolines (C5) and Tetrahydroquinolines (C6) by Pd/S,O-Ligand Catalysis.

Herein, we report a highly selective C-H olefination of directing-group-free indolines (C5) and tetrahydroquinolines (C6) by Pd/S,O-ligand catalysis. In the presence of the S,O-ligand, a wide range of challenging indolines, tetrahydroquinolines, and olefins was efficiently olefinated under mild reaction conditions. The synthetic potential of this methodology was demonstrated by the efficient olefination of several indoline-based natural products.

Domino Radical Addition/Oxidation Sequence with Photocatalysis: One-Pot Synthesis of Polysubstituted Furans from α-Chloro-Alkyl Ketones and Styrenes.

A new domino reaction has been developed that allows the combination of styrenes and α-alkyl ketone radicals to afford a wide array of polysubstituted furans in good to excellent yields under mild and simple reaction conditions. The key to success of this novel protocol is the use of photocatalyst fac-Ir(ppy)3 and oxidant K2 S2 O8 . Mechanistic studies by a radical scavenger and photoluminescence quenching suggest that a radical addition/oxidation pathway is operable.

Homocoupling of 3-Halooxindole via Visible-Light Photocatalysis: A Mild Access to 3,3'-Bioxindoles.

This paper introduces a simple way to the homocoupling of tertiary halides induced by photocatalysis. This method features mild reaction conditions, excellent functional group tolerance, high yields, low photocatalyst loading and successful application to the highly sterically hindered systems. On the basis of the reaction results, a novel stable-radical-induced homocoupling reaction mechanism has been proposed.

Autoxidation/Aldol Tandem Reaction of 2-Oxindoles with Ketones: A Green Approach for the Synthesis of 3-Hydroxy-2-Oxindoles.

In the presence of tetrabutylammonium fluoride and molecular sieves (MS) 4 Šin DMF, an efficient autoxidation reaction of 2-oxindoles with ketones under air at room temperature has been developed. This approach may provide a green, practical, and metal-free protocol for a wide range of biologically important 3-hydroxy-3-(2-oxo-alkyl)-2-oxindoles.

Visible-light-driven difluoroacetamidation of unactive arenes and heteroarenes by direct C-H functionalization at room temperature.

The directed difluoroacetamidation of unactivated arenes and heteroarenes with bromodifluoroacetamides via visible-light photoredox catalysis has been efficiently achieved at room temperature. Broad utility of this transformation is presented, including electronically deficient heteroaromatic and aromatic systems. The mechanistic pathway of the difluoroacetamidation was discussed based on photoluminescence quenching, spin-trapping, and kinetic isotope effect experiments.