Direct construction of 4-aryl tetralones via visible-light-induced cyclization of styrenes with molecular oxygen

Abstract

A direct synthesis of 4-aryltetralones from aromatic alkenes and O2 using acridinium as the photocatalyst under visible light irradiation was developed.

C(sp2)–H/O–H cross-dehydrogenative coupling of quinoxalin-2(1H)-ones with alcohols under visible-light photoredox catalysis

“…A plausible mechanistic cycle for the photocatalytic CDC reaction of quinoxalin-2(1H)-ones and alcohols based on the control experiments and literature reports [22,48,57] is shown in Scheme 4. The reaction initiated with the activation of acridinium catalyst A by the irradiation of visible light, generating the excited-state species (B), which subsequently undergoes a single-electron transfer (SET) process along with quinoxa-lin-2(1H)-one 1 to afford the corresponding radical cation intermediate (C) and the acridine radical (D).…”

“…However, the efficient utilization of dioxygen (or ambient air) is challenging, because the existence of a triplet-ground-state of molecular oxygen largely blocks oxygen reduction and selective transformation with a large kinetic barrier, and the four-electron reduction of molecular oxygen involves more electrons than the two-electron substrate oxidation. In the past decade, the photocatalytic reaction using dioxygen (or ambient air) as a terminal oxidant has become a research hotspot of green chemistry [57][58][59][60][61][62][63][64][65][66][67][68][69], because it is very consistent with the 12 principles of green chemistry. However, to the best of our knowledge, no example of the synthesis of 3-alkoxylquinoxalin-2(1H)-ones through the visible-light photocatalytic CDC reaction with ambient air as the sole oxidant exists.…”

Photocatalytic hydrogen-evolution dimerization of styrenes to synthesize 1,2-dihydro-1-arylnaphthalene derivatives using Acr+-Mes and cobaloxime catalysts

“…This skeleton contains an alkene C=C bond that can be easily derivatized; for example, podophyllotoxin with high anticancer activity can be constructed by using this skeleton as a precursor [7,8]. Over the past decades, a variety of effective methods such as Friedel-Crafts reaction [9], Heck reaction [10], metal-catalyzed intramolecular epoxidation [11], and others [12,13] have been developed for the construction of 1,2-dihydro-1-arylnaphthalenes [14][15][16][17][18][19][20][21]. Nevertheless, these methods often require substrate pre-functionalization and high temperatures, and have limited product regioselectivity.…”

Photoredox‐Catalyzed Dimerization of Arylalkenes via an Oxidative [4+2] Cycloaddition Sequence: Synthesis of Naphthalene Derivatives

“…As a result, we found a new, formal [4+2] annulation of arylalkenes under photoirradiated conditions with an organic photosensitizer, Acr + ‐Mes (9‐mesityl‐10‐methylacridinium perchlorate) . With the incorporation of a keto functionality during the annulation cascade sequence, 3,4‐dihydronaphthalen‐1(2 H )‐ones were assembled in the open air whereas, under an N 2 atmosphere, (dihydro)naphthalenes were constructed efficiently by using Selectfluor as the oxidant (Scheme c) . 3,4‐Dihydronaphthalen‐1(2 H )‐ones (1‐tetralones) are found in natural products that exhibit interesting biological, pharmaceutical and medicinal properties .…”