2-Hydroxy-3-oxocarboxylic esters

Hydroxy-3-oxocarboxylic esters.2 p-Alkyl-a,(i-unsaturated esters (1) are oxidized to these esters (2) by KMn04 in mildly acidic aqueous acetone at -10° in 60-85% yield. 

Asymmetric synthesis by means of a cyandiydrin is an imprvtant process in organic synthesis, because the cyanohydrin can be easily converted into a variety of valuable synthetic intermediates, such as a-hy-droxy ketones, a-hydroxy acids, y-diketones, p-amino alcohols, 4-oxocarboxylic esters, 4 xonitriles, a-amino acids and acyl cyanides. More specifically, the (S)-cyanohydrin of m-phenoxybenzaldehyde is a building block for the synthesis of the insecticide deltamethrin, or (IR)-cis-pyrethroids. ... 

Enders D, Dyker H, Raabe G (1993 a) Enantioselective aldol reactions with a phosphoenolpuryvate equivalent asymmetric synthesis of 4-hydroxy-2-oxocarboxylic acid esters. Angew Chem Int Ed Engl 32 421-423... 

Important components of hard cheeses (Gouda type) include some carboxylic acid esters (ethyl butanoate, ethyl hexanoate), as well as carboxylic acids (acetic, butyric, isobutyric, valeric, isovaleric, 2-methylbutyric and caproic acids). Cheeses manufactured using bacteria of the genus Propionibacterium (such as Emmental and Gruyere) contain propionic acid and other lower fatty acids, methyl thioacetate, some oxocarboxylic acids, various alcohols, esters (such as ethyl butanoate), lactones (such as 8-decalactone), amines and other basic compounds (also skatole in addition to aliphatic amines), alkylpyrazines (e.g. 2-sec-butyl-3-methoxypyrazine), 4-hydroxy-2,5-dimethyl-2H-furan-3-one (furaneol), 2-ethyl-4-hydroxy-5-methyl-2H-furan-3-one (homofuraneol) and a range of other compounds. 

Two procedures for the preparation of a-oxocarboxylic acids via nitrile intermediates have been described. The autoxidation of 3,3-disubstituted 2-cyanocarboxylate ester anions is reported to provide the related a-oxoesters in fair yield a new general procedure for the conversion of aldehydes into the homologous a-oxoacids is based on theoxidationof a-hydroxy-iV-t-butyl-carboxamides (116), prepared by the acid-catalysed alcoholysis of aldehyde cyanohydrins with t-butanol, to the hitherto ui nown -oxocarboxamides, which are in turn readily converted into the parent a-oxoacids on acid-catalysed hydrolysis. 

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