Photoamidation of 2,3,4,6-tetra-<i>O</i>-acetyl-1-deoxy-<scp>D</scp>-<i>arabino</i>-hex-1-enopyranose and of (<i>Z</i>)-3-deoxy-3-<i>C</i>-(methoxycarbonyl)methylene-1,2:5,6-di-<i>O</i>-isopropylidene-α-<scp>D</scp>-<i>ribo</i>-hexofuranose

Abstract

The acetone-initiated photochemical addition of formamide to 2,3,4,6-tetra-O-acetyl-1-deoxy-D-arabino-hex-1-enopyranose (1) afforded 3,4,5,7-tetra-O-acetyl-2,6-anhydro-D-glycero-D-ido-heptonamide (2), 3,4,5,7-tetra-O-acetyl-2,6-anhydro-D-glycero-D-talo-heptonamide (3), and 4,5,6,8-tetra-O-acetyl-3,7-anhydro-1-deoxy-2-methyl-D-glycero-D-talo-octitol (4), in 55, 7, and 23% yields, respectively. Reduction of 2 with diborane followed by acetylation yielded 1-acetamido-3,4,5,7-tetra-O-acetyl-2,6-anhydro-1-deoxy-D-glycero-D-ido-heptitol (7) in 70% yield. Deacetylation of 2 and 3 with sodium methoxide yielded the unsubstituted heptonamides 5 and 6.Photoamidation of (Z)-3-deoxy-3-C-(methoxycarbonyl)methylene-1,2:5,6,-di-O-isopropylidene-α-D-ribo-hexofuranose (8) yielded 3-C-[R and S-carbamoyl(methoxycarbonyl)methyl]-3-deoxy-1,2:5,6-di-O-isopropylidene- α-D-allofuranose (9) and (10).