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Selective Ring-Opening Polymerization of Di-O-t-butyldimethylsilylated and Di-O-p-bromobenzylated 1,4-Anhydro-α-L-arabinopyranoses and Structural Analysis of Free Arabinans
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Takashi Yoshida1), Masuo Kida1) and Toshiyuki Uryu1)
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1) Institute of Industrial Science, University of Tokyo
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ABSTRACT: We report herein studies of ring-opening polymerization of 1,4-anhydro-2,3-di-O-t-butyldimethylsilyl-α-L-arabinopyranose (ADSA) and 1,4-anhydro-2,3-di-O-p-bromobenzyl-α-L-arabinopyranose (ADBA) by cationic initiation in methylene chloride. Polymerization of ADSA using phosphorus pentafluoride as initiator at −60°C gave stereoregular (1→5)-α-L-arabinofuranan derivatives in 85% yield. Polymerization of ADBA with various Lewis acids afforded slightly less stereoregular polymers (α-content 90%) under optimum conditions. Deprotection of both substituted polymers resulted in a free polysaccharide having the same structure, (1→5)-α-L-arabinofuranan. The polymer structure was characterized by 13C NMR spectroscopy, specific rotation, and the methylation analysis using GC-MS spectroscopy.
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Keyword: Ring-Opening Polymerization/ Cationic Initiation/ 13C NMR/ 2D NMR/ Specific Rotation/ Free Polysaccharide/ Methylation Analysis/ GC-MS Spectroscopy
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Published online: April 08, 2005 |
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© Copyright, 2005 by The Society of Polymer Science, Japan |
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