Arylazo-glycenosides. Part II. Additions of dienes and dimethylsul-phoxonium methylide to some 2- and 3-arylazo-derivatives of methyl 4,6-O-benzylidene-2,3-dideoxy-D-hex-2-enopyranosides

Abstract

Methyl 4,6-O-benzylidene-2,3-dideoxy-2-phenylazo-α-D-hex-2-enopyranoside reacted with dimethylsulphoxonium methylide, by addition of a methylene group to the carbon–carbon double bond of the azoalkene system, to give methyl 4,6-O-benzylidene-2,3-dideoxy-2,3-C-methylene-2-phenylazo-α-D-allopyranoside. In contrast, methyl 4,6-O-benzylidene-2,3-dideoxy-3-phenylazo-α-D-hex-2-enopyranoside gave, upon treatment with this ylide, a mixture of 1′-phenyl (methyl 4,6-O-benzylidene-2,3-dideoxy-α-D-arabino- and ribo-hexopyranosido [3,2-c]-Δ^2′-pyrazolines. The β-anomer behaved in like fashion, but only one of the isomeric products was isolated. Support for a structure having fused five- and six-membered rings was obtained by oxidative degradation studies, in which one of the α-isomers was converted into 1-phenylpyrazole-3,4-dicarboxylic acid.

The α-anomers of the 2- and 3-phenylazo-derivatives of methyl 4,6-O-benzylidene-2,3-dideoxy-D-hex-2-eno-pyranoside both form adducts with acrylonitrile and methyl acrylate, and the α-anomer of the 3-phenylazo-derivative has been shown to give an adduct with dimethylacetylene dicarboxylate.