1,2:5,6-Di-O-cyclohexylidene-3-C-methyl-α-D-allofuranose and other branched-chain analogues

Abstract

The reactions of 1,2:5,6-di-O-cyclohexylidene-α-D-ribo-3-hexofuranosulose with methylmagnesium bromide and with methyl-lithium yield the same 3-C-methyl derivative; the configuration of this compound was established by preferential hydrolytic removal of the 5,6-O-cyclohexylidene residue, oxidative removal of C-6 with periodate, and a consideration of the properties of the isolated product, 1,2-O-cyclohexylidene-3-C-methyl-α-D-ribo-pentodialdofuranose, in comparison with those of 1,2-O-cyclohexylidene-α-D-ribo-pentodialdofuranose and the dimer of 1,2-O-cyclohexylidene-α-D-xylo-pentodialdofuranose. The configuration of the products obtained by the reactions of ethyl-, vinyl-, phenyl, and 1-naphthyl-magnesium halides and of phenyl-lithium with 1,2:5,6-di-O-cyclohexylidene-α-D-ribo-3-hexofuranosulose is discussed.