α-Keto Acids: Acylating Agents in Organic Synthesis

Abstract

A significant number of important acyl-transfer reactions, such as direct acylation, ortho acylation, heteroatom acylation, and a diversity of cyclization reactions using the title compound as a key starting material, have been described in recent years. Just like a sleeping beauty, α-oxocarboxylic acids were awakened from a 17-year sleep to become important reagents in classical and new acylation reactions. The greener characteristic of the coproduct formed in reactions using α-keto acid (only CO 2 ), together with its versatility as a building block in catalytic organic synthesis, accredit it as a candidate to green acylating agent, an alternative to acyl chloride, and other acyl-transfer reagents. This review presents the impressive breakthroughs achieved mainly in the past decade in the development of new catalytic reactions for the formation of C−C, C−N, and C−S bonds using α-keto acids. CONTENTS 1. Introduction 7113 2. Classical Methods and Recent Advances in the Synthesis of α-Keto Acids 7115 2.1. Physical Properties of α-Keto Acids 7119 3. α-Keto Acids in Acylation Reactions 7119 3.1.

Two antibacterial and PPARα/γ-agonistic unsaturated keto fatty acids from a coral-associated actinomycete of the genus Micrococcus

“…α-Keto fatty acids are characterized by the presence of a keto group at the α-position of a carboxylic acid moiety. They are present in all living cells and play crucial roles in biological systems as they are involved in the Krebs cycle and glycolysis [20]. In contrast, keto fatty acids bearing a keto group in the middle of the carbon chain are relatively limited in their distribution in nature.…”

Single‐Step Synthesis of Dehydroalanine Derivatives via a Brønsted Acid‐Catalyzed Multicomponent Reaction

“…Pyruvic acid ( 2 ), benzamide ( 3 a ), and 4‐chlorobenzyl alcohol ( 4 a ) were used to identify the optimum reagent combination by using various Brønsted acids (Table ). Phosphoric acid diphenyl phosphate or trifluoromethanesulfonimide showed poor yields, indicating that significantly weaker or stronger Brønsted acids than p ‐toluenesulfonic acid (PTSA) were inefficient (Table , entries 1–2) . Methanesulfonic acid (Table , entry 4) gave 1 a in 21 % yield.…”

“…Indeed, polymerization of Dha has been reported in the literature . However, the formation of the side product could be interpreted as a further reaction of the product 1 with A , generated by decarboxylation of pyruvic acid ( 2 ) at a high temperature, 1,5‐hydride transfer onto the tethered Dha acceptor, and finally hydrolysis of the imide C (Scheme )…”

Aldehydes: magnificent acyl equivalents for direct acylation

“…have been explored extensively. [11][12][13][14] Amongst these acylating surrogates, aldehydes (aliphatic and aromatic) have received profound…”