Showing papers on "Glycal published in 1972"

Modifications of lincomycin involving the carbohydrate portion. Part I. The 2-O-methyl and 2-deoxy-analogues

Abstract: 2-O-Methyl-lincomycin has been synthesised via the O-methylation of either methyl N-acetyl-3,4-O-isopropylid-ene-1-thiolincosaminide or its 6-deamino-7-deoxy-2′-methyl-[6,7-d]-Δ2′-oxazoline derivative, obtained from methyl thiolincosaminide, the carbohydrate portion of the antibiotic lincomycin. The glycal obtained by treatment of either of the anomeric N-acetyl-2,3,4,7-tetra-O-acetyl-lincosaminyl bromides with zinc, reacts normally with hydrogen bromide to give the anomeric N-acetyl-3,4,7-tri-O-acetyl-2-deoxylincosaminyl bromides, thereby providing a route to 2-deoxy-α- and β-lincomycins. The effect of the structural modifications in these analogues on antibacterial activity is discussed.

Modified Synthesis of 1-Deoxyald-1-enopyranose (2-Hydroxyglycal) Esters: Conversion of 1,2-Unsaturated Pyranoid Compounds into 2,3-Unsaturated Glycopyranosyl Derivatives

Abstract: Publisher Summary This chapter discusses the modified synthesis of 1-deoxyald-l-enopyranose (2-hydroxyglycal) esters The hydroxyglycal esters, more systematically described as esters of 1-deoxyald-l-enopyranoses, are well-known compounds prepared by the elimination of the elements of hydrogen halide from acylated glycosyl halides An alternative modification involves the conversion of glycosyl bromides to iodides prior to the eliminations Esters of 1-deoxyald-l-enopyranoses can also be converted to 2,3-unsaturated glycopyranosides by treatment in benzene solution with alcohols in the presence of boron trifluoride etherate In the glycal (1,2-dideoxyald-l-enopyranose) series, rearrangement reactions can be effected similarly, and in particular, 4,6-di-O-acetyl-2,3-dideoxy-α- d -erythro-hex-2-enopyranosides can be synthesized from tri-O-acetyl- d -glucal