Methyl furanosides

Galactose methyl furanoside H NMR, 4, 579 <64CC369> of-Glucose methyl furanoside H NMR, 4, 579 (64CC369)... 

The effect of lactone ring-size on the inhibition was studied, for N-acetyl-)3-D-glucosaminidase from bovine epididymis, with lactones and lactone derivatives unable to undeigo ring-isomerization, by Pokomy and co-workers. From a comparison of Kj values for 2-acetamido-2-deoxy-D-glu-cono-1,5-lactone (0.45 nM) with the 1,4-lactone (4.5 fiM) and of Kj for the methyl ) -furanoside with that for the pyranose (4 mM), it was concluded that the 1,4-lactone has an 10-fold lower inhibitory potency than the 1,5-lactone. The weak inhibition by the 5,6-O-isopropylidene derivative of the... 

After anomerisation and before initiation of the ring-expansion process, the a-and p-glucofuranosides were found to be present in a -equilibrium in the ratio 1 1.7 which agrees with the value obtained by radiochemical methods and with that observed by Bishop and Cooper for the methyl xylofuranosides 4). However, the ratio for the xylosides was found in the isotope work to be 1 1.2 (1 1.3 for ethyl xylofuranosides) regardless of whether they were derived from xylose or either of its methyl furanosides. A further relevant observation made with these furanosides was that acetal was formed during their anomerisation indicating that pathways (C) and (E) (Scheme 3) are open. 

Table 1. First order rate constants for methyl furanoside anomerisations (2% solution in 0.01% methanolic hydrogen chloride at 35 °C)...

Table 29 1H NMR Data for Anomeric Methyl Furanosides (64MI31002>...

When D-glucose is treated with acidic methanol, the first products which can be isolated are mainly methyl furanosides, but after extensive reaction the furanosides disappear and methyl glucopyrano-sides accumulate. Why ... 

Table 29 H NMR Data for Anomeric Methyl Furanosides" (64MI31002)...

The cydization of 3- m-butyldimethylsilvloxy-4,5-hexadienal. performed in methanol with a catalytic amount of palladium(II) chloride under an atmosphere of carbon monoxide in the presence of propylene oxide and triethyl orthoacetate, leads to a methyl furanoside in 88 % crude yield and total diastereoselection151. 

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