Two novel synthetic methods for 1,4-anhydro-alpha-D-xylopyranose derivatives

摘要

Two novel methods for the syntheses of 1,4-anhydro-3-O-benzyl-2-O-pivaloyl- (1) and 2-O-acetyl-1,4-anhydro-3-O-benzyl-alpha-D-xylopyranose (2), starting materials for synthesizing stereoregular beta-(1-->5)-xylofuranan by ring-opening polymerization are reported. Both synthetic routes start from D-xylopyranose, involve nine reaction steps, and give approximately 30-35% overall yields. The key reaction in the novel synthetic routes is the intramolecular nucleophilic attack of C-1 oxyanion on the C-5 position of 3-O-benzyl-5-O-(p-toluenesulfonyl)-alpha-D-xylofuranose (10), resulting in 1,5-acetal bond formation in high yield. The present synthetic routes enable us to prepare 1,4-anhydro-alpha-D-xylopyranose derivatives having different substituents at the 2-O- and the 3-O-positions. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 15]