Enzymic glycosylation of (±)-(3,5/4,6)-3,6-diazido-4,5-dihydroxycyclohexene. A way to prepare stereochemically pure and enzyme resistant, basic pseudo-disaccharides as competitive enzyme inhibitors

By beta-D-galactosylation of (+/-)-(3,5/4,6)-3,6-diazido-4,5-dihydroxycyclohexane, pure (+)-(3,5/4,6)-3,6-diazido-4-O-(beta-D-galactopyranosyl)-5-hydroxycyclohexen (3) was obtained. The diamine (+)-(1,3/2,6)-3,6-diamino-1-O-(beta-D-galactopyranosyl)-2-hydroxycyclohexane derived from compound 3 by catalytic hydrogenation, is stable against enzymic cleavage and competitively inhibits beta-D-galactosidase from Escherichia coli with a K-i-value of 5.5 mM. Sigmatropic rearrangement of 3 in methanolic solution partially led to an unseparable mixture of the regioisomers (3,5/4,6)-3,4-diazido-5-O-(beta-D-galactopyranosyl)-6-hydroxycyclohexe and (3,5/4,6)-3,4-diazido-6-O-(beta-D-galactopyranosyl)-5-hydroxycyclohexe. Catalytic hydrogenation thereof yielded an equally unseparable mixture of the diamines (1,3/2,4)-1,2-diamino-3-O-(beta-D-galactopyranosyl)-4-hydroxycyclohexa and (1,3/2,4)-1,2-diamino-4-O-(beta-D-galactopyranosyl)-3-hydroxycyclohexane, inhibiting beta-D-galactosidase competitively with K-i 0.9 mM.