Silver-Catalyzed Double-Decarboxylative Cross-Coupling of α-Keto Acids with Cinnamic Acids in Water: A Strategy for the Preparation of Chalcones

Abstract

A silver-catalyzed double-decarboxylative protocol has been proposed for the construction of chalcone derivatives via cascade coupling of substituted α-keto acids with cinnamic acids under the mild aqueous conditions. The developed method for constructing C-C bonds via double-decarboxylative reactions is efficient, practical, and environmentally benign by using the readily available starting materials. It should provide a promising synthesis candidate for the formation of diverse and useful chalcone derivatives in the fields of synthetic and pharmaceutical chemistry.

Recent advances in catalytic decarboxylative acylation reactions via a radical process

“…We speculated that it is formed through the oxidative cleavage of benzoxazoles followed by condensation with α-keto acids. And the control experiments 30 confirmed that the o-aminophenol might be the key intermediate. 9b Recently, Liu and Li et al have successfully achieved the decarboxylative 2-acylation of oxazoles and thiazoles with α-keto acids under a novel Co/Ag 2 CO 3 catalytic system (Scheme 3).…”

“…In this field, commercial avaliable Selectfluor has been widely utilized as 30 fluorine source to construct the C-F bond. 14 In 2014, we developed a novel Ag(I)-catalyzed decarboxylative acylfluorination of styrenes with α-keto acids and Selectfluor.…”

“…In all cases, only trans isomers were obtained, which might be due to minimizing the strain of phenyl 20 and benzoyl groups on six-membered ring (Scheme 13). 16b 25 Scheme 13 Silver-catalyzed decarboxylative acylarylation of 30 cinnamamides.…”

“…2 Among them, α-keto acids are usually utilized as acylating agents to deliver a carbonyl group into organic molecules via the decarboxylative coupling. For 30 example, transition-metal-catalyzed decarboxylative acylation of C sp2 −X bonds or unactivated C sp2 −H bonds with α-keto acids offers an appealing alternative for the synthesis of diaryl ketones. 3 To date, numerous efficient protocols involving Pd or Pd/Ag, Ag, Cu and visible-light photoredox catalysis have been 35 explored for these decarboxylative transformations.…”

Chalcone: A Privileged Structure in Medicinal Chemistry

“…The aryl radical is added to the cinnamate anion at the α -position, leading to the formation of chalcone with another molecular loss of carbon dioxide and Ag(I). 142 The strategy of using saturated propiophenones to produce unsaturated chalcones has also been demonstrated using a combination of decarboxylation and dehydrogenation (Scheme 8D). 147 The researchers crosscoupled aryl carboxylic acids using a PCy 3 -supported palladium catalyst to obtain chalcones in fair yields, which is an extension of the Heck reaction that overcomes the limits of its starting materials.…”