The new 6-deoxy-D-allal- and 6-deoxy-D-galactal-derived allyl epoxides 8α and 8β have been stereoselectively prepared and their behaviour as glycosyl donors in addition reactions with nucleophiles examined and compared with that of the corresponding 6-OR (R= Bn, Tr) substituted epoxides. The completely stereoselective substrate-dependent glycosylation process found in the reaction of 8α and 8β with O-nucleophiles (alcohols and partially protected monosaccharides) and C-nucleophiles (alkyl lithium compounds and TMSCN), indicated that a 6-OR group in the side chain is not necessary for determining the selectivity. The reaction of 8α and 8β with azide (TMSN3, N-nucleophile) made it possible to revise a previously proposed rationalization for the formation of the corresponding cis azido alcohol (syn-1,2-addition product).

Synthesis of diastereoisomeric 6-deoxy-D-allal- and 6-deoxy-D-galactal-derived allyl epoxides and examination of the regio- and stereoselectivity in nucleophilic addition reaction. Comparison with the corresponding 6-O-functionalized allyl epoxides

DI BUSSOLO, VALERIA;FAVERO, LUCILLA;PINESCHI, MAURO;CROTTI, PAOLO
2008

Abstract

The new 6-deoxy-D-allal- and 6-deoxy-D-galactal-derived allyl epoxides 8α and 8β have been stereoselectively prepared and their behaviour as glycosyl donors in addition reactions with nucleophiles examined and compared with that of the corresponding 6-OR (R= Bn, Tr) substituted epoxides. The completely stereoselective substrate-dependent glycosylation process found in the reaction of 8α and 8β with O-nucleophiles (alcohols and partially protected monosaccharides) and C-nucleophiles (alkyl lithium compounds and TMSCN), indicated that a 6-OR group in the side chain is not necessary for determining the selectivity. The reaction of 8α and 8β with azide (TMSN3, N-nucleophile) made it possible to revise a previously proposed rationalization for the formation of the corresponding cis azido alcohol (syn-1,2-addition product).
DI BUSSOLO, Valeria; Favero, Lucilla; ROMANO M., R; Pineschi, Mauro; Crotti, Paolo
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11568/193935
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