Direct Synthesis of Thioesters from Feedstock Chemicals and Elemental Sulfur.

The development of a mild, atom- and step-economical catalytic strategy that effectively generates value-added molecules directly from readily available commodity chemicals is a central goal of organic synthesis. In this context, the thiol-ene click chemistry for carbon-sulfur (C-S) bond construction has found widespread applications in the synthesis of pharmaceuticals and functional materials. In contrast, the selective carbonyl thiyl radical addition to carbon-carbon multiple bonds remains underdeveloped.

Oxygen mediated oxidative couplings of flavones in alkaline water.

Catalyzed oxidative C-C bond coupling reactions play an important role in the chemical synthesis of complex natural products of medicinal importance. However, the poor functional group tolerance renders them unfit for the synthesis of naturally occurring polyphenolic flavones. We find that molecular oxygen in alkaline water acts as a hydrogen atom acceptor and oxidant in catalyst-free (without added catalyst) oxidative coupling of luteolin and other flavones.

Photomediated reductive coupling of nitroarenes with aldehydes for amide synthesis.

In view of the widespread significance of amide functional groups in organic synthesis and pharmaceutical studies, an efficient and practical synthetic protocol that avoids the use of stoichiometric activating reagents or metallic reductants is highly desirable. A straight-forward pathway to access amides from abundant chemical feedstock would offer a strategic advantage in the synthesis of complex amides. We herein disclose a direct reductive amidation reaction using readily available aldehydes and nitroarenes enabled by photo-mediated hydrogen atom transfer catalysis.

Divergent functionalization of aldehydes photocatalyzed by neutral eosin Y with sulfone reagents.

While aldehydes represent a classic class of electrophilic synthons, the corresponding acyl radicals are inherently nucleophilic, which exhibits umpolung reactivity. Generation of acyl radicals typically requires noble metal catalysts or excess oxidants to be added. Herein, we report a convenient and green approach to access acyl radicals, capitalizing on neutral eosin Y-enabled hydrogen atom transfer (HAT) photocatalysis with aldehydes.

Visible light driven deuteration of formyl C-H and hydridic C(sp)-H bonds in feedstock chemicals and pharmaceutical molecules.

Deuterium labelled compounds are of significant importance in chemical mechanism investigations, mass spectrometric studies, diagnoses of drug metabolisms, and pharmaceutical discovery. Herein, we report an efficient hydrogen deuterium exchange reaction using deuterium oxide (DO) as the deuterium source, enabled by merging a tetra--butylammonium decatungstate (TBADT) hydrogen atom transfer photocatalyst and a thiol catalyst under light irradiation at 390 nm. This deuteration protocol is effective with formyl C-H bonds and a wide range of hydridic C(sp)-H bonds ( α-oxy, α-thioxy, α-amino, benzylic, and unactivated tertiary C(sp)-H bonds).