Anhydro sugar polymerization

Basic characteristics of 1,6-anhydro sugar polymerization are given in Table 8.1. 

This anhydro sugar, polymerized at —60 °C in CHjC12 solvent with 0.5-1.0 mol % PFS initiator, gives high-molecular-weight polymer (Mn up to 7 105) with a >50% yield, which after debenzylation shows a specific rotation between +181° and +197° 29). 

Mechanistic Aspects of Anhydro Sugar Polymerization Related to Polymer Structure and Synthetic Applications... 

Lewis acids were usually used as initiators, PFS being the most common choice. Recently, 31P- and 19F-NMR was used to study kinetic features of anhydro sugar polymerization initiated with PFS 29,30). PFS generated by the thermal decomposition of p-ClC6H4N2+ PF was introduced into a solution of anhydro sugar (8-30) in CH2C12,... 

The first investigation of the polymerization of an anhydro sugar was reported by Pictet21 shortly after his preparation of l,6-anhydro-/3-... 

The synthesis of other anhydro sugar derivatives is usually accomplished by an internal displacement of a leaving group with inversion, as has already been emphasized for those anhydrides in which the anhydride bridge engages the anomeric position. Three such compounds that have been used in polymerizations deserve specific mention 5,6-anhydro-l,2-0-isopropylidene-a-D-glucofuranose,12 13 its 3-methyl ether,11 and 3,5-anhydro-l,2-0-isopropylidene-a-D-xylo-furanose,14 all of which were synthesized by p-toluenesulfonylation of the primary hydroxyl group of the parent, isopropylidene derivative, followed by treatment with base. 

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