Nonyl Acridine Orange as a Prospective Photocatalyst in Chalcogenylation of Coumarins and Quinolinones

Abstract

A mild and efficient method for preparation of 3-sulfenyl and 3-selenyl coumarins and quinolinones mediated by artificial light or sunlight is presented. The elaborated protocol highlights the use of nonyl acridine orange as a photocatalyst to generate a sulfenyl radical from thiols that is further trapped by a heterocycle. The utility of the protocol is justified by a diverse scope of thiols, including short cysteine-containing peptides. The same reaction conditions can be applied for preparation of 3-selenyl coumarins and quinolinones. Various protected and unprotected selenocysteine-containing peptides were successfully utilized demonstrating high tolerance for amino acids with sensitive groups (Arg, Lys, Trp, His, and Tyr).

Visible‐Light‐Active Coumarin‐ and Quinolinone‐Based Photocatalysts and Their Applications in Chemical Transformations

“…This process was carried out under 460 nm light-emitting diodes (LEDs) or sunlight irradiation using nonyl acridine orange (NAO) as a photocatalyst (Scheme 16). [33] Without the use of external additives, the atom-economic chalcogenylation process took place using various sulfur and selenium sources. Specifically, for the sulfenylation reactions, thiols, thiourea, thiocyanates, and cysteine-containing oligopeptides partici- pated in the transformation of the coumarin core, producing the corresponding 3-sulfenyl coumarins.…”

Regioselective synthesis of phenanthridine-fused quinazolinones using a 9-mesityl-10-methylacridinium perchlorate photocatalyst

“…Based on the control experiments and literature report, 23 a plausible mechanism is depicted in Fig. 6.…”

Photoredox-Catalyzed Redox-Neutral Decarboxylative C–H Acylations of Coumarins with α-Keto Acid

“…These privileged scaffolds are widely present in pharmaceutical compounds and possess significant biological activities such as anticancer, anti-HIV, antimicrobial, antifungal, antioxidant, anti-inflammatory, and anticoagulant activities. − Therefore, chemists have spent a great deal of effort to develop powerful and reliable methods for the synthesis of coumarin derivatives. A quick survey of the literature highlights various synthetic methods for functionalization of coumarin at position C-3 by transition metal catalysis or photocatalysis. − Though a huge amount of progress has been achieved in C-3 functionalization, − after decades of research, practical methods for the functionalization of coumarin at position C-4 are still lacking. Among the well-known procedures, palladium-catalyzed cross-coupling and nickel-catalyzed cross-coupling were regarded as two of the predominant approaches. , Wu and Yang described nickel-catalyzed cross-coupling of 4-diethylphosphonooxycoumarins with organozinc bromides to give 4-substituted coumarins (Scheme a) .…”