REACTIONS OF NITRO SUGARS: II. THE CONVERSION OF METHYL 6-DEOXY-6-NITRO-HEXOPYRANOSIDES INTO DEOXYNITROINOSITOLS BY ALKALINE GLYCOSIDE CLEAVAGE

Abstract

Methyl 6-deoxy-6-nitro-D-glucopyranoside and methyl 6-deoxy-6-nitro-L-idopyranoside under mild alkaline conditions undergo fission of the pyranoside ring followed by loss of the aglycon and cyclization of the resulting nitro sugars to a mixture of scyllo and myo-1 deoxynitroinositols. A mechanism for the alkaline glycoside cleavage is proposed in which a 5,6-di-deoxy-6-nitro-aldos-5-ene is an intermediate. The susceptibility to attack by base of such nitroolefins has been studied using 3-O-acetyl-5,6-dideoxy-1,2-O-isopropylidene-6-nitro-α-D- xylo-hexofuranos-5-ene. It has been shown that this compound, when treated with methanolic sodium hydroxide, is methoxylated in position 5 and that this methoxylation occurs more rapidly than de-O-acetylation. The significance of this reaction with regard to alkaline acetal and ketal cleavages in the nitro sugar series is discussed.