Asymmetric alkene-alkene reductive cross-coupling reaction via visible-light photoredox/cobalt dual catalysis.

The first example of asymmetric alkene-alkene reductive coupling is demonstrated via visible-light-fueled photoredox/cobalt dual catalysis. The desymmetrization reaction provided products (>20 examples) with up to five chiral centers in single-step operation in up to 95% yields with very high relative (>99 : 1 dr) and absolute stereochemistry (up to 98 : 2 er) control. The preliminary mechanistic investigations suggested that the critical mechanistic steps involved light-mediated controlled low-valent cobalt complex generation, oxidative ene-ene cyclization, and protonation.

Sustainable Synthesis of α-Hydroxycarboxylic Acids by Manganese Catalyzed Acceptorless Dehydrogenative Coupling of Ethylene Glycol and Primary Alcohols.

Herein, we report a straightforward synthesis of valuable α-hydroxycarboxylic acid molecules via an acceptorless dehydrogenative coupling of ethylene glycol and primary alcohols. A bench-stable manganese complex catalyzed the reaction, which is scalable, with the product being isolated with high yields and selectivities under mild conditions. The protocol is environmentally benign, producing water and hydrogen gas as the only byproducts. Methanol can also be used as a C1 source for producing the platform molecule lactic acid, with a high turnover of >104 . The methodology was also used to functionalize alcohols derived from natural products and fatty acids. Furthermore, it was applied for synthesizing α-amino acid, α-thiocarboxylic acid, and several drugs and bioactive molecules, including endogenous metabolites, Danshensu, Enalapril, Lisinopril, and Rosmarinic acid. Preliminary mechanistic studies were performed to shed light on the mechanism involved in the reaction.

Photoredox/Nickel Dual Catalysis Enables the Synthesis of Alkyl Cyclopropanes via C(sp3)-C(sp3) Cross Electrophile Coupling of Unactivated Alkyl Electrophiles.

A facile synthesis of mono-, 1,1- and 1,2-disubstituted cyclopropanes via visible light-mediated photoredox/nickel dual catalysis is demonstrated. The challenging intramolecular C(sp3)-C(sp3) cross-electrophile coupling of readily available unactivated 1,3-dialkyl electrophiles was performed under mild conditions that allowed traditionally reactive functional groups to be included. Mechanistic inspection and control experiments revealed the importance of dual catalysis and that the reaction proceeds via a stepwise oxidative addition followed by an intramolecular SN2 reaction.