A mild and green photochemical protocol for the oxidation of alcohols to aldehydes and ketones was developed.

, [a] Nikolaos F. Nikitas, [a] Errika Voutyritsa, [a] Dimitrios I. Tzaras, [a] Nikolaos Kaplaneris, [a] and Christoforos G. Kokotos* [a] CÀ H functionalization at the α-position of heterocycles has become a rapidly growing area of research. Herein, a cheap and efficient photochemical method was developed for the CÀ H functionalization of heterocycles. Phenylglyoxylic acid (PhCO-COOH) could behave as an alternative to metal-based catalysts and organic dyes and provided a very general and wide array of photochemical CÀ H alkylation, alkenylation, and alkynylation, as well as CÀ N bond forming reaction methodologies. This novel, mild, and metal-free protocol was successfully employed in the functionalization of a wide range of CÀ H bonds, utilizing not only O-or N-heterocycles, but also the less studied S-heterocycles.

Employing a bifunctional catalyst based on a copper­(I)/NHC complex and a guanidine organocatalyst, catalytic ester reductions to alcohols with H2 as terminal reducing agent are facilitated. The approach taken here enables the simultaneous activation of esters through hydrogen bonding and formation of nucleophilic copper­(I) hydrides from H2, resulting in a catalytic hydride transfer to esters. The reduction step is further facilitated by a proton shuttle mediated by the guanidinium subunit. This bifunctional approach to ester reductions for the first time shifts the reactivity of generally considered “soft” copper­(I) hydrides to previously unreactive “hard” ester electrophiles and paves the way for a replacement of stoichiometric reducing agents by a catalyst and H2.

Alkenes are very important moieties in organic chemistry and have been employed as starting materials for the synthesis of important organic compounds. In this review, we present organocatalytic reactions in which alkenes play a central role, especially their organocatalytic oxidation to epoxides. This topic plays a pivotal role in our recent research, for which we utilize H2O2 as a green oxidant and a ketone as the catalyst. Extension to other oxidative transformations is also presented.