Review on Asymmetric Catalysis Employing 5H‐Oxazol‐4‐Ones as α‐Hydroxy Carboxylic Acid Surrogates

Abstract

Heterocycles play an essential role in medicinal as well as in organic synthetic chemistry. The synthesis of these valuable scaffolds is an emerging and challenging field of today‘s research in organic chemistry. In recent years, several heterocycles as new synthons have emerged as potential nucleophiles in asymmetric transformations. Among them, 5H‐oxazol‐4‐one is one of the strategic synthons for synthesizing enantioenriched α‐alkyl‐α‐hydroxycarboxylic acid derivatives, which are otherwise very challenging via direct installation of a hydroxy group at the α‐position of carbonyls. Over the years, considerable progress has been made to establish new and efficient methodologies under mild reaction conditions exploiting metal‐ and organo‐catalysis. This review presents a comprehensive summary of various catalytic development in asymmetric synthesis employing 5H‐oxazol‐4‐ones as α‐alkyl‐α‐hydroxycarboxylic acid surrogates.

Ligand-Enabled Pd-Catalyzed Enantioselective Synthesis of Quaternary Amino Acids and Glycolic Acids Derivatives

“…[28][29][30] As such, its analogue, 5H-oxazol-4-one, which differs only in the relative positions of heteroatoms from the azalactone, can also serve as potential nucleophiles in variety of catalytic asymmetric reactions to afford chiral 5,5-disubstituted oxazol-4-ones. 31 Similar to azalactobe, the 5,5disubstituted oxazol-4-ones can be readily converted into the corresponding chiral glycolic acids. Despite massive achievements involving alkylations, to our best knowledge, the general asymmetric arylation reaction are hence unknown so far, in both azalactones and 5H-oxazol-4-ones.…”

Recyclable Polymer Supported DMAP Catalyzed Cascade Synthesis of α-Pyrones

“…45,46 On the other hand, 5H-oxazol-4-one is one of the strategic C-center pronucleophiles and serves as a potential surrogate of α-hydroxy carboxylic acid. 51 Oxazolones have been extensively used in many asymmetric transformations yielding structurally diverse scaffolds. 51 However, the reaction potential of oxazolones in cyclization/annulation reactions has not been further explored.…”

“…51 Oxazolones have been extensively used in many asymmetric transformations yielding structurally diverse scaffolds. 51 However, the reaction potential of oxazolones in cyclization/annulation reactions has not been further explored.…”