Photochemical oxidation of benzylic primary and secondary alcohols utilizing air as the oxidant

Abstract

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

Photochemical Functionalization of Heterocycles with EBX Reagents: C−H Alkynylation versus Deconstructive Ring Cleavage**

“…Elimination of peroxide would then lead to X . However, 4 a is known to be a mediocre sensitizer for singlet oxygen generation, [19l] and side‐products resulting from sulfur overoxidation would have been expected in the presence of singlet oxygen [6a] . Finally, a mechanism involving alkynylation of sulfur, followed by attack of water and oxidation appears less probable, as side product 7 would not have been observed in this case, and the alkynylation process is known to require a copper catalyst and high temperature to proceed [17c] …”

Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones

“…As a mild, efficient, and environmentally friendly approach it has the potential to unlock unique reactions that are previously inaccessible under thermal conditions. Significant advances were made for the oxidation of benzylic alcohols by using metal-based photocatalysts [38][39][40][41][42][43][44][45][46] and metal-free photocatalysis [47][48][49][50][51][52][53] in combination with various oxidants, such as TBHP and DDQ [54,55]. However, the reported methods require either specific nanoparticle catalysts [39][40][41][42] or the catalytic method is limited to electron-rich or electronneutral benzylic alcohols [56].…”

Photochemical Reaction of N,N‐Dimethylanilines with N‐Substituted Maleimides Utilizing Benzaldehyde as the Photoinitiator

“…We initiated our study utilizing 4‐bromo‐ N , N ‐dimethylaniline ( 1 a ) and N ‐phenylmaleimide ( 2 a ), in order to find the optimum catalyst (Table 1). Thioxanthen‐9‐one ( 4 a ) [10k,l] and phenylglyoxylic acid ( 4 c ), [10a–i] afforded mediocre yields (Table 1, entries 1–3). Aromatic aldehydes, as aromatic ketones, have shown catalytic activity upon irradiation in organic synthetic reactions or in polymerization reactions [3f,10j] .…”