β-Oxy-α-diazo-carbonyl compounds. Part 5: An improved synthesis of β-hydroxy-α-diazo esters derived from monosaccharides and synthetic applications in the chemistry of 3-deoxy-2-ulosonic acids

Reactions of ethyl 2-diazoacetate with aldehydo sugars and monosaccharide derivatives in their hemiacetal form are reported. The use of diethyl zinc led to an improvement of yields and shorter reaction times compared with neutral conditions as previously described. The resulting products represent potentially useful substrates for the synthesis of 3-deoxy-2-keto-ulosonic acid derivatives. Thus, diazo derivatives from d-mannose were transformed into Ko and 3-epimer Ko derivatives in a straightforward process by reaction with mCPBA.