SYNTHESIS AND CRYSTAL-STRUCTURES OF 7-ACETAMIDO-7,8-DIDEOXY-1,2-3,4-DI-O-ISOPROPYLIDENE-BETA-L-THREO-D-GALACTO-OCTOPYRANOSE AND 7-ACETAMIDO-6-O-ACETYL-7,8-DIDEOXY-1,2-3,4-DI-O-ISOPROPYLIDENE-ALPHA-D-ERYTHRO-D-GALACTO-OCTOPYRANOSE

7-Acetamido-7,8-dideoxy-1,2:3,4-di-O-isopropylidene-α-D-erythro- (14) and -threo- and -β-L-erythro- and -threo- (17) octopyranose, intermediates for the synthesis of analogs of the antibiotic lincomycin, have been synthesized from a mixture of 7,8-dideoxy-7-C-nitro-octoses prepared from D-galactose. O-Acetylation of 14 gave the 6-acetate (18). The configurations of C-6 and C-7 in compounds 17 and 18 were determined by X-ray crystallography. The crystals of compound 17 are monoclinic, space group C2, with Z 4, in a unit cell of dimensions a 1.825(1) nm, b 947(1) pm, and c 1.123(1) nm. The crystals of compound 18 are orthorhombic, space group P212121, with Z 12, in a unit cell of dimensions a 2.814(2) nm, b 1.302(1) nm, and c 1.713(1) nm. © 1979.