A photoreactor from a collaboration between the MacMillan Lab and Merck could provide a widespread tool for synthetic chemists in the photoredox space.

We describe a cobalt-catalyzed hydroacylation of 1,3-dienes with non-chelating aldehydes. Aromatic aldehydes provide 1,4-addition products as the major isomer, while aliphatic aldehydes favor 1,2-hydroacylation products. The kinetic profile supports an oxidative cyclization mechanism involving a cobaltacycle intermediate that undergoes transformation with high regio- and stereoselectivity.

We describe a Rh-catalyzed desymmetrization of all-carbon quaternary centers from α,α-bis(allyl)aldehydes by a cascade featuring isomerization and hydroacylation. This desymmetrization competes with two other novel olefin functionalizations that are triggered by C-H bond activation, including carboacylation and bisacylation. A BIPHEP ligand promotes enantioselective formation of α-vinylcyclopentanones. Mechanistic studies support irreversible and enantioselective olefin-isomerization followed by olefin-hydroacylation.

Over the past 40 years, intramolecular hydroacylation has favored five-membered rings, in preference to four membered rings. Herein, we report a catalyst derived from earth-abundant cobalt that enables preparation of cyclobutanones, with excellent regio-, diastereo-, and enantiocontrol, under mild conditions (2 mol % catalyst loading and as low as 50 °C).