Visible-light- and bromide-mediated photoredox Minisci alkylation of N-heteroarenes with ester acetates

Abstract

A visible-light-induced photoredox Minisci alkylation reaction of N-heteroarenes with ethyl acetate has been reported. The low-toxic ethyl acetate was used for the first time as alkylation reagent. Hence, 4-quinazolinones, quinolines...

Photoredox Neutral Decarboxylative Hydroxyalkylations of Heteroarenes with α-Keto Acids

“…Subsequently, the addition of acyl radical A to the protonated N-heteroarene in a Minisci-type pathway occurs to give the radical cation B . Deprotonation of B leads to the α-amino radical C , which undergoes a spin center shift (SCS) process to afford the α-oxy radical D . The SET process of D with the excited photocatalyst (*Ir III ) followed by protonation provides the target compound 3 while regenerating the active oxidized photocatalyst (Ir IV ).…”

Synthetic Applications of Photocatalyzed Halogen‐Radical Mediated Hydrogen Atom Transfer for C−H Bond Functionalization

“…Later on, the same group adopted a similar system for the bromine-mediated alkylation of quinolines and quinazolinones using different hydrogen donors such as aldehydes [89,90] and ester acetates (Scheme 17B). [91] Very recently, the group has developed a decarbonylative strategy to accomplish the hydroalkylation of acrylamides with aldehydes. [92] Quite recently, Murakami and co-workers developed a cross-dehydrogenative coupling between benzylic and aldehydic CÀ H bonds (Scheme 18).…”

Bromine radical enhanced stoichiometric pyridylation of alkylarenes and diarylmethanes at room temperature

“…6 Recently, the boom in radical chemistry has boosted the development of radical-based strategies for the synthesis of alkylpyridines, as exemplified by Minisci-type reactions. 7–18 This method proceeds via the direct addition of an alkyl radical to heteroaromatics, but stoichiometric Brønsted acid and external oxidants are typically required in most cases (Scheme 1a). A series of alkyl radical sources, such as aliphatic acids, 7 boronic acids, 8 alcohols, 9 alkanes, 10 aldehydes, 11 alkylfluoroborates, 12 alkyl halides, 13 alkyl esters, 14 alkyl peroxides 15 NHPI 16 and ethers, 17 have been reported for Minisci C–H alkylation via photocatalysis.…”

“…7–18 This method proceeds via the direct addition of an alkyl radical to heteroaromatics, but stoichiometric Brønsted acid and external oxidants are typically required in most cases (Scheme 1a). A series of alkyl radical sources, such as aliphatic acids, 7 boronic acids, 8 alcohols, 9 alkanes, 10 aldehydes, 11 alkylfluoroborates, 12 alkyl halides, 13 alkyl esters, 14 alkyl peroxides 15 NHPI 16 and ethers, 17 have been reported for Minisci C–H alkylation via photocatalysis. However, unfavourable characteristics, such as poor regioselectivity, overalkylation and harsh reaction conditions, hinder the use of Minisci-type reactions in research.…”