Moenuronic acid

As usual, glycosulose derivatives have been favoured starting materials. Methyl-lithium was used to introduce the branch methyl in the uronic acid (5), which served as a reference compound to establish the D-configuration of moenuronic acid in moenomycin. Sequential use of methyl and aryl Grignard reagents allowed the... 

D-Moenuronic acid, a component of the antibiotic moenamycin A, has been shown to be 4-C-methyl-o-glucuronic acid by characterization of its ethyl furanosidurono-6,3-lactone derivative (1) obtained after acid hydrolysis and ethanolysis of the antibiotic. The gluco configuration was established by n.m.r. analysis of derivatives of (1), including the 1,6-anhydrofuranose derivative (2) obtained after borohydride treatment of the lactone. 

The 4-ulose (7) derived from glucose reacts stereospecifically with methyl lithium at -78° to give the 4-C-methyl glucose adduct which was used to prepare the moenuronic acid glycoside (8) at the same temperature, methyl magnesium iodide gave the D-galacto-isomer specifically. ... 

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