Dual Copper Photoredox C-H Alkynylation with Arylacetylenes.

In the realm of organic synthesis, direct C-H alkynylation with arylacetylenes has remained a daunting challenge due to competing annulations or alkenylation. Addressing this long-standing issue, herein we demonstrate the merging of copper and photocatalysis to achieve the elusive C-H alkynylation of benzamides using arylacetylenes or arylpropiolic acids. Unlike conventional copper-mediated C-H activations, our protocol circumvents the need for high temperatures and stoichiometric amounts of copper salts or metal/non-metal oxidants.

Expedient radical phosphonylations ligand to metal charge transfer on bismuth.

Bismuth, in spite of its low cost and low toxicity, has found limited application in organic synthesis. Although the photoactivity of Bi(iii) salts has been well studied, this has not been effectively exploited in photocatalysis. To date, only a single report exists for the Bi-based photocatalysis, wherein carbon centered radicals were generated using ligand to metal charge transfer (LMCT) on bismuth.

Ru(II)-Catalyzed [4 + 2]-Annulation and Arylation of 1,4-Naphthoquinones.

Naphthoquinones form the core of a variety of drugs and natural products. As a result, the conjugation of 1,4-naphthoquinones with organic building blocks would offer a facile strategy toward scaffolds of biological interest. In this regard, we hereby report a Ru(II)-catalyzed [4 + 2] annulation of 1,4-naphthoquinones with benzoic acids to afford various naphthoquinone lactones.