Biocatalytic route to well-defined macromers built around a sugar core.
By using 4-C-hydroxymethyl-alpha-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-alpha-D-pentofuranose (diastereomeric excess up to 93%); (2) the ring-opening of epsilon-caprolactone, epsilon-CL, from the remaining primary hydroxyl group to give an acryl-sugar capped macromer (M(n) = 11 300, M(w)/M(n) = 1.36, initiator efficiency 50-55%, <5% water initiated PCL chains); (3) selective lipase-catalyzed esterification of the terminal hydroxyl of oligo(epsilon-CL) chains; (4) hydrolysis of the 1,2-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.
Kumar
Rajesh
R
NSF Center for Biocatalysis and Bioprocessing of Macromolecules, Department of Chemistry and Chemical Engineering, Polytechnic University, Six Metrotech Center, Brooklyn, New York 11201, USA.
Gross
Richard A
RA
D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D008049:Lipase / Q000737:chemistry / Q000378:metabolism
D002241:Carbohydrates; D008049:Lipase