Studies on sugar nitro-olefins. Part 7. Synthesis of 3-(alditol-1-yl)-1,2,3,5,6,7-hexahydro- and -1,5,6,7-tetrahydro-indol-4-ones. X-Ray molecular structure of (3S)-3-(1,2,3,4,5-penta-O-acetyl-D-galacto-pentitol-1-yl)-1,2,3,5,6,7-hexahydroindol-4-one

Abstract

Raney nickel reduction of (3R)-2-hydroxyimino-3-(1,2,3,4,5-penta-O-acetyl-D-galacto- or -D-gluco-pentitol-1-yl)-3,5,6,7-tetrahydrobenzofuran-4(2H)-ones (5) gives (3S)-3-(1,2,3,4,5-penta-O-acetyl-D-galacto- or -D-galaco-pentitol-1-yl)-1,2,3,5,6,7-hexahydroindol-4-ones (6) in high yields. Deacetylation of compounds (6) with catalytic sodium methoxide in methanol affords the corresponding (pentitol-1-yl)indolones (7). Compounds (6) can be transformed into the 3-(1,2,3,4,5-penta-O-acetyl-D-galacto- or -D-gluco-pentitol-1-yl)-1,5,6,7-tetrahydroindol-4-ones (8) by treatment with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. The structure of (3S)-3-(1,2,3,4,5-penta-O-acetyl-D-galacto-pentitol-1-yl)-1,2,3,5,6,7-hexahydroindol-4-one (6a) was confirmed by an X-ray structure determination.