Synthesis of 2,3-dioxo-2,3-dihydro-4-methyl-6-chloro-1H-pyrrolo[2,3-b]pyridine and its 1-α-L-arabinopyranoside
A new type of isatin analog-2,3-dioxo-2,3-dihydro-4-methyl-6-chloro-1H-pyrrolo[2,3-b]pyridine — was obtained by oxidation of 4-methyl-6-chloro-1H-pyrrolo(2,3-b]pyridine. Condensation of L-arabinose with 4-methyl-6-chloro-2,3-dihydropyrrolo[2,3-b]pyridine and subsequent acetylation and dehydrogenation gave 1-(2,3,4-tri-O-acetyl-α-L-arabinopyranosyl)-4-methyl-6-chloropyrrolo[2,3-b]pyridine, which served as the starting compound for the synthesis of 1-α-L-arabinopyranosyl-4-methyl-6-chloropyrrolo[2,3-b]pyridine. Oxidation of 1-(2,3,4-tri-O-acetylα-L-arabinopyranosyl)-4-methyl-6-chloropyrrolo[2,3-b]pyridine gave 1-(2,3.4-tri-O-acetyl-α-L-arabinopyranosyl)-2,3-dioxo-2,3-dihydro-4-methyl-6-chloropyrrolo [2,3-b]pyridine.