Homo-C-nucleoside analogs IV. Synthesis of 4-(2,5-anhydro-D-altro-pentitol-1-yl)-2-phenyl-2H-1,2,3-triazole homo-C-nucleoside. CD assignment of the absolute configuration of the carbon bridge.
Dehydrative cyclization of 4-(D-altro-pentitol-1-yl)2-phenyl-2H-1,2,3-triazole in basic medium with one moler equivalent of p-toluene sulfonyl chloride in pyridine solution gave the homo-C-nucleoside 4-(2,5-anhydro-D-altro-1-yl)-2-phenyl-2H-1,2,3-triazole. The structure and anomeric configuration was determined by acylation, nuclear magnetic resonance (NMR), and mass spectroscopy. The stereochemistry at the carbon bridge of homo-C-nucleoside 2-phenyl-2H-1,2,3-triazoles was determined by circular dichroism (CD) spectroscopy.
Studies on anhydro-osazones. Part 5. Structure and anomeric configuration of the C-nucleoside analogues obtained from the dehydration of D-gluco- and D-manno-hept-2-ulose phenylosazones
Dehydration of D-gluco- and D-manno-hept-2-ulose phenylosazones with methanolic sulphuric acid afforded the anomeric furanosyl anydro-osazone pair: 3,6-anhydro-D-manno-hept-2-ulose phenylosazone (2), and the gluco-analogue osazone (3). A new type of anomeric pyranosyl anhdro-osazone [3,7-anhydro-D-manno-hept-2-ulose phenylosazone (4) and the gluco-analogue (5)] was also identified. Refluxing the anhydro-osazones with copper sulphate afforded the anomeric furanosyl C-nucleoside analogues 4-α-D-arabinofuranosyl-2-phenyl-v-triazole (6) and the β-isomer (7), and the arabinopyranosyl isomers (8) and (9). The structures and anomeric configurations of the products were determined by periodiate oxidation, o.r.d., and n.m.r. spectroscopy. The mechanism of the dehydration and the mass spectra of compounds (6)–(9) are discussed.
Effect of a new inhibitor of cholesterol biosynthesis (AY 9944) on serum and tissue sterols in the rat.
AY 9944 is a novel inhibitor of cholesterol biosynthesis which appears to act on the Delta 7-reductase enzyme, interfering with the conversion of 7-dehydrocholesterol to cholesterol. In all tissues studied, with the exception of the lens, there was a reduction in cholesterol and a marked accumulation of 7-dehydrocholesterol. Isotope studies showed a reduced uptake of acetate into cholesterol, and an increased uptake into 7-dehydrocholesterol, in various tissues in vivo and by skin samples in vitro. There was no apparent accumulation of lanosterol or of the methostenols in the rat skin.