Human milk oligosaccharides: an enzymatic protection step simplifies the synthesis of 3′- and 6′-O-sialyllactose and their analogues
摘要:
We describe a chemo-enzymatic synthesis of 3'- and 6'-O-sialyllactose, two trisaccharides occurring in the 'acidic fraction' of the human milk oligosaccharides and endowed with potential antiadhesive activity. The key step is the highly regioselective 6'-O-acylation of benzyllactoside, which gave access to suitably protected lactose building blocks to be used as acceptors in the sialylation reaction. Moreover, the synthesis of the carboxymethyl and sulfo analogues of the title compounds is reported. (C) 2002 Elsevier Science Ltd. All rights reserved.
polyhydroxylated steroids has been systematically investigated. The enzyme showed a mark preference forthe alcoholic moieties on the A ring and on the steroidal side chain, making it possible the selective acylation at the positions 3 or 21 of polyhydroxy steroids. Acylation with the synthetically useful ester choloroacetate and levulinate was also accomplished, whereas esterification with benzoate and
Lipase-Catalysed Regioselective Acylations in Combination with Regioselective Glycosylations as a Strategy for the Synthesis of Oligosaccharides: Synthesis of a Series of Fucosyllactose Building Blocks
Simple and regioselective lipase-catalyzed acylation of compounds 1 and 4 with synthetically useful esters such as benzoates, chloroacetates, pivaloates and levulinates is described.