Syntheses and reactions of 5-O-acetyl-1,2-anhydro-3-O-benzyl-α-d-ribofuranose and -β-d-lyxofuranose, 5-O-acetyl-1,2-anhydro-3,6-di-O-benzyl- and 1,2-anhydro-5,6-di-O-benzoyl-3-O-benzyl-β-d-mannofuranose, and 6-O-acetyl-1,2-anhydro-3,4-di-O-benzyl-α-d-glucopyranose and -β-d-talopyranose
作者:Jun Ning、Fanzuo Kong
DOI:10.1016/s0008-6215(00)00290-1
日期:2001.1
The title compounds 5-O-acetyl-1,2-anhydro-3-O-benzyl-alpha -D-ribofuranose and 5-O-acetyl-1,2-anhydro-3-O-benzyl-beta -D-lyxofuranose, and 6-O-acetyl-1,2-auhydro-3,4-di-O-benzyl-alpha -D-glucopyranose and 6-O-acetyl-1,2-anhydro-3,4-diO-benzyl-beta -D-taloypranose, and 5-O-acetyl-1,2-anhydro-3,6-di-O-benzyl-beta -D-mannofuranose and 1,2-anhydro-5,6-di-O-benzoyl-3-O-benzyl-beta -D-mannofuranose have each been synthesized from the corresponding 2-O-tosylate and 1-free hydroxyl inter-mediates by base-initiated intramolecular S(N)2 ring closure in almost quantitative yields. Acetyl and benzoyl groups were not affected in the ring closure reactions. Condensation of 6-O-acetyl-1,2-anhydro-3,4-di-O-benzyl-alpha -D-glucopyranose and 5-O-acetyl-1,2-anhydro-3,6-di-O-benzyl-beta -D-mannpfuranose with 1,2:3,4-di-O-isopropylidene-alpha -D-galactopyranose in the presence of ZnCl2 as the catalyst afforded the 1,2-trans-linked 6-O-acetyl-3,4-di-O-benzyl-alpha -D-glucopyranosyl-(1-6)-1,2:3,4-di-O-isopropylidene-alpha -D-galactopyranose and 5-O-acetyl-3,6-di-O-benzyl-alpha -O-mannofuranosyl-(1-->6)-1,2:3,4-di-O-isopropylidene-a-D-galactopyranose as the sole products in satisfactory yields, while condensation of 5-O-acetyl-1,2-anhydro-3-O-benzyl-beta -D-lyxofuranose with 3-O-benzyl-1,2-O-isoproyylidene-alpha -D-xylofuranose yielded the 1,2-trans-linked 5-O-acetyl-3-O-benzyl-alpha -D-lyxofuranosyl-(1-->5)-3-O-benzyl-1,3-O-isopropylidene-alpha -D-xylofuranose as the sole product in a good yield. The 6-O-acetyl group in the glycosyl donor, 6-O-acetyl-1,2-anhydro-3,4-di-O-brnzyl-alpha -D-glucopyranose did not influence the stereoselectivity of the ring-opening-coupling, reaction. (C) 2001 Published by Elsevier Science Ltd. All rights reserved.