Biocatalytic Route to Well-Defined Macromers Built around a Sugar Core

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Abstract
By using 4-C-hydroxymethyl-α-d-pentofuranose as the sugar core and lipase-catalyzed transformations, a macromer was constructed with exceptional control of substituent placement around the carbohydrate core. The key synthetic transformations performed were as follows: (1) selective lipase-catalyzed acrylation along with prochiral selection of 4-C-hydroxymethyl-1,2-O-isopropylidene-α-d-pentofuranose (diastereomeric excess up to 93%); (2) the ring-opening of ε-caprolactone, ε-CL, from the remaining primary hydroxyl group to give an acryl-sugar capped macromer (Mn = 11 300, Mw/Mn = 1.36, initiator efficiency 50−55%, O-isopropylidene group at the sugar core without any substantial loss in macromer molecular weight; and (5) homopolymerization of the corresponding macromer. In principle, the method developed is flexible so that it can be used to generate a wide array of unusual macromers and heteroarm stars. In the absence of biocatalytic transformation, such structural control would be extremely difficult or currently impossible to obtain.