Zinc‐Catalyzed Dehydrogenative Cross‐Coupling of Terminal Alkynes with Aldehydes: Access to Ynones

Cross-Dehydrogenative Alkynylation: A Powerful Tool for the Synthesis of Internal Alkynes

Alkynes are among the most fundamentally important organic compounds and are widely used in synthetic chemistry, biochemistry, and materials science. Thus, the development of an efficient and sustainable method for the preparation of alkynes has been a central concern in organic synthesis. Cross-dehydrogenative coupling utilizing E-H and Z-H bonds in two different molecules can avoid the need for prefunctionalization of starting materials and has become one of the most straightforward methods for the construction of E-Z chemical bonds. This Review summarizes recent progress in the preparation of internal alkynes by cross-dehydrogenative coupling with terminal alkynes.

Photochemical Hydroacylation of Michael Acceptors Utilizing an Aldehyde as Photoinitiator

The hydroacylation of Michael acceptors constitutes a useful tool for the formation of new C-C bonds. In this work, an environmentally friendly procedure was developed, utilizing 4cyanobenzaldehyde as the photoinitiator and household bulbs as the irradiation source. A great variety of substrates was well-tolerated, leading to good yields, and mechanistic experiments were performed to elucidate the catalyst's possible mechanistic pathway. Moreover, the inherent selectivity challenge regarding α,α-disubstituted aldehydes (decarbonylation problem) was studied and addressed.

Alkynylation of Csp2 (O)-H Bonds Enabled by Photoredox-Mediated Hydrogen-Atom Transfer

The development of new hydrogen-atom transfer (HAT) strategies within the framework of photoredox catalysis is highly appealing for its power to activate a desired C-H bond in the substrate leading to its selective functionalization. Reported here is the first photoredox-mediated hydrogen-atom transfer method for the efficient synthesis of ynones, ynamides, and ynoates with high regio- and chemoselectivity by direct functionalization of Csp2 (O)-H bonds. The broad synthetic application of this method has been demonstrated by the selective functionalization of C(O)-H bonds within complex molecular scaffolds.