Precision synthesis of (1>6)- alpha -D-glucopyranan by cationic ring-opening polymerization of 1,6-anhydro-2,3,4-tri-O-allyl-B-D-glucopyranose

The ring-opening polymerization of 1,6-anhydro-2,3,4-tri-O-allyl- beta -D-glucopyranose (2) has been carried out using various cationic initiators. For the condition of [2]/[BF3.OEt2] = 20 at -15C for 90 h, the polymer yield, Mw and Mw/Mn of the polymer obtained were 79%, 215,600 and 3.45, respectively. In order to study the living characteristic of the polymerization of 2, the cationic ring-opening bulk polymerization initiated by trimethylsilyl trifluoromethanesulfonate (TMSOTf) was carried out under the condition of [2]/[TMSOTf] = 1000 at -15 C. The Mw value increased in proportion to conversion until c.a. 30% and below. The Mw/Mns of resulting polymers were very narrow, e.g., the Mw/Mn value was 1.2 and below, which was smaller than that for the solution polymerization using BF3.OEt2. These results indicated that the ring-opening bulk polymerization of 2 using TMSOTf was living-like.