Ligand Promoted Pd-Catalyzed High para-Selective C-H Olefination.

Achieving high para-selective C-H functionalized products of benzoic acid derivatives using a designed template is still a daunting challenge because the carbonyl group also could coordinate with metal to activate the ortho-C-H bond. Herein, we report the ligand promoted high para-selective C-H olefination of benzoic acid derivatives; we screened a series of ligands increasing the ratio of p:others from 62:38 to 96:4. This work may find application in the construction of para-substituted benzoic acid derivatives.

A Cheap and Efficient Oxidant (n-Bu)4NNO3-Enabled C(sp2)- and C(sp3)-H Olefination at Room Temperature.

To further promote the widely practical application of C-H activation, developing green and mild reaction conditions has invariably been the objective of researchers, especially when it comes to remote C-H activation reactions. Herein, we report a new cheap and powerful (n-Bu)4NNO3 oxidant. This oxidant is efficient and universal for Pd(II)-catalyzed sp2 and sp3 C-H olefination and allows the reaction to be carried out at room temperature. Because of this, we attempted to make C-H functionalization more economical and environmentally benign.

Cobalt(III)-catalyzed weakly coordinating arylurea-directed regioselective mono-olefination.

Here, we developed an air-stable, earth-abundant cobalt(III)-catalyzed regioselective mono-olefination of arenes directed by urea under mild conditions through a cross-dehydrogenative coupling (CDC) process. Under the optimized conditions, a high regioselectivity of mono-olefination was achieved with various electron-rich and electron-deficient arenes, which afforded E-alkenylated products (with yields of up to 90%). In contrast to the conditions used for noble-metal-catalyzed olefination directed by weakly coordinating groups, our reaction was operated under mild conditions, including mild temperature (40 °C) and non-metallic oxidant.