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Direct Decarboxylative Allylation and Arylation of Aliphatic Carboxylic Acids Using Flavin‐Mediated Photoredox Catalysis
Author(s) -
Ramirez Nieves P.,
LanaVillarreal Teresa,
GonzalezGomez Jose C.
Publication year - 2020
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201900888
Subject(s) - chemistry , decarboxylation , deprotonation , carboxylic acid , reactivity (psychology) , alkyl , catalysis , radical , benzothiazole , photoredox catalysis , photocatalysis , organic chemistry , flavin group , photochemistry , combinatorial chemistry , medicine , ion , alternative medicine , pathology , enzyme
We describe herein a direct decarboxylative allylation of aliphatic carboxylic acids with allylsulfones using visible light and riboflavin tetraacetate (RFTA) as photocatalyst. The reaction proceeds at room temperature tolerating a wide range of functionalities, avoiding the use of external bases or additives. Mechanistic studies support that alkyl radicals are involved in the reaction and that a true photocatalytic cycle is operating. It is proposed that the carboxylic acid is deprotonated by [RFTA] · – , and the corresponding carboxylate acts as a reductive quencher of RFTA*, which after decarboxylation produces the alkyl radical. The methodology was adapted to prepare benzothiazoles substituted at C2, by reacting some carboxylic acids with 2‐(phenylsulfonyl)benzothiazole. The number of carboxylic acids suitable for this arylation was lower than for the allylation and this different reactivity was briefly commented.