Soluble polymer-supported enzymatic synthesis

The multipolymer enzymatic resolution of soluble polymer-supported alcohols 42 and 43 was achieved using an immobilised lipase from Candida Antarctica (Novozym 435). The R-alcohol was obtained in enantiomerically pure form (>99% ee) after its cleavage from the poly(ethylene) glycol (PEG) scaffold . The achiral hydantoin- and isoxazoline-substituted dispirocyclobutanoids 47 were produced using both solution and solid-phase synthesis <00JOC3520, OOCC1835>. 

Huang X, Witte KL, Bergbreiter DE, Wong C-H. Homogenous enzymatic synthesis using a thermo-responsive water-soluble polymer support. Adv Synth Catal 2001 343 675-681. 

Oligosaccharide syntheses employing enzymatic reactions would in principle greatly benefit from being performed on a polymer support since the support might effectively facilitate isolation of the final product. Presumably, a water-soluble polymeric support will be preferable to any insoluble support since reaction rates could otherwise become too slow. Glycosidases as synthetic enzymes would be the best candidates to study this type of the enzymic approach to oligosaccharide synthesis. 

Solution phase supports have the problem of product recovery. An alternative approach is to couple the substrate to a water-soluble polymer that can be removed from solution by precipitation of the polymer or size exclusion chromatography. Water-soluble supports have been used in the enzymatic synthesis of pseudo-GM3 (118). 

The endoglycosidase, ceramide glycanase, is used to transfer an oligosaccharide group from a water-soluble polymer to ceramide. This enzymatic tool provides an efficient new method for polymer-supported synthesis of glycosphingolipids (119). 

Wong and coworkers have investigated the enzymatic oligosaccharide synthesis on a thermoresponsive polymer support (Scheme 16.33). The copolymers of 7V-/-propyla-crylamide (NIPAm) and functionalized monomers are thermoresponsive and exhibit inverse temperature-dependent solubility in water they are soluble in cold water but become... 

We shall describe enzymatic glycosylations that have been achieved on both insoluble and soluble supports, because, irrespective of the nature of the support, polymer-supported synthesis is based on the same concept, and good results with soluble supports have been reported in the literature. 

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