(3-Epimerization in the corrinoid system has recently emerged as a complicating factor in the latter stages of the total synthesis of vitamin B12 (Eschenmoser 1971; Woodward 1973). I t has also found some application in biosynthetic studies on the origin of the methyl groups in ring C (Scott, Townsend & Cushley 1973; Scott, this Discussion p. 303). This paper sets out to review briefly the (3-e...

There have been many reports of epimerization of salvinorins at C-8 under basic conditions, but little evidence has been presented to establish the structure of these compounds. We report here the first crystal structure of an 8-epi-salvinorin or derivative: the title compound, 2b. The lactone adopts a boat conformation with the furan equatorial. Several lines of evidence suggest that epimeriza...

The mechanism of the enzymic isomerization and epimerization of D-erythrose 4-phosphate (Ery4P) by an enzyme preparation from bovine liver was investigated with the use of 2H2O. The incorporation of 2H was quantitatively determined by a procedure using gas chromatography-mass spectrometry. About one atom of 2H was incorporated per molecule of the enzymic epimerization reaction product of Ery4P ...

Organocatalysis for polymer chemistry has become a subject of significant interest in the last two decades. In this contribution, we have studied evolution microstructure poly(L-lactide) solution toluene at 105 °C presence various organocatalysts. Weak bases such as triethylamine and DMAP (4-dimethylaminopyridine) lead to low extent epimerization chain scission reaction. The DBU (1,8-diazabicyc...

BACKGROUND Lactulose, a synthetic disaccharide, has received increasing interest due to its role as a prebiotic, specifically proliferating Bifidobacilli and Lactobacilli and enhancing absorption of calcium and magnesium. The use of cellobiose 2-epimerase (CE) is considered an interesting alternative for industrial production of lactulose. CE reversibly converts D-glucose residues into D-mannos...

UDP-N-acetyl-L-fucosamine is a precursor to l-fucosamine in the lipopolysaccharide of Pseudomonas aeruginosa serotype O11 and the capsule of Staphylococcus aureus type 5. We have demonstrated previously the involvement of three enzymes, WbjB, WbjC, and WbjD, in the biosynthesis of UDP-2-acetamido-2,6-dideoxy-L-galactose or UDP-N-acetyl-L-fucosamine (UDP-l-FucNAc). An intermediate compound from ...