Preparation of “Sugar-Coated” Homopolymers and Multiblock ROMP Copolymers

Ring-opened homopolymers of 5-norbornene-2-carboxylates or 5-norbornene-2,3-dicarboxylates that contain acetal-protected sugars ( 1: 1,2:3,4-di- O -isopropylidene-α- d -galactopyranos-6- O -yl 5-norbornene-2-carboxylate; 2: bis(1,2:3,4-di- O -isopropylidene-α- d -galactopyranos-6- O -yl) 5-norbornene- trans -2,3-dicarboxylate; 3: 5-norbornene-2-carboxylic acid ester containing 2,3- O -isopropylidene- d -ribonic γ-lactone; 4: 3,4:5,6-di- O -isopropylidene-α- d -mannofuranos-1- O -yl 5-norbornene-2-carboxylate) were prepared in toluene using Mo(CHCMe 2 Ph)(N-2,6- i -Pr 2 C 6 H 3 )(O- t -Bu) 2 as the initiator. These homopolymers showed narrow molecular weight distributions (PDI = 1.02−1.25) and a molecular weight dependent on the number of monomers added. Di-, tri-, and tetrablock copolymers containing 1 − 4, methyltetracyclododecene (MTD, 5 ), or trans -2,3-bis(((trimethylsilyl)oxy)methyl)-norborn-5-ene ( 6 ) were also prepared and found to have low polydispersities ( M w / M n = 1.03−1.25). The cyclic acetal in polymers containing 1 or 2 could be removed using CF 3 CO 2 H/H 2 O (9/1 v/v, 15 min, 22 °C) to afford the corresponding water-soluble polymers containing the parent sugar.