Optical activity cellulose esters

Among optically active polymers, polysaccharide derivatives are particularly valuable. Polysaccharides such as cellulose and amylose are the most readily available optically active polymers and have stereoregular sequences. Although the chiral recognition abilities of native polysaccharides are not remarkable, they can be readily converted to the esters and carbamates with high chiral recognition abilities. The chiral recognition mechanism of these derivatives has been clarified to some extent. 

Roussel [3] prepared chiral polysaccharide esters by grafting a-phenylpro-pionic acid, (R)-, (IV), and (S)-ibuprofen, or (R)- and (S)-naproxen onto cellulose. These agents were then used for isolating optically active acids. 

Enantioselective packings Polar or nonpolar Packings with enantioselective cages or enantioselective surfaces, microcrystalline cellulose triacetate, cellulose ester or cellulose, carbamate/sil-ica composites, optically active poly(acrylamide)/silica composites, chemically modified silicas (Pirkle phases), cydodextrine modified silicas Operated either with normal phase or reversed phase mobile phases... 

In optical device application, biomass-derived cellulose esters are being studied actively as a potential material for optical films. Besides being derived from abundantly available biomass resources, they also possess characteristics suitable as optical films such as high transparency and excellent heat resistance [8]. By virtue of these properties, cellulose esters provide huge possibilities for future development of optical films in order to meet the market demands. 

Edgar et al. (2001) have focused on the performance of cellulose esters in modern coatings, controlled release of actives, plastics (with particular focus on biodegradable plastics), composites and laminates, optical films, and membranes and related separation media [29]. 

Known bicyclo[4.3.1]enone 15758 was converted into vinylsilane 158 with bis(trimethylsilyl)methyl lithium.55 Diene 158 underwent selective ozonolysis at the cis-olefin under conditions to produce differentially oxidized termini 90 alde-hydo-ester 159 was homologated with a phosphine oxide anion91 to enol 160. Subsequent hydrolysis of 161 provided substrate 162, which after tandem ozonolysis-acidification gave racemic 6,9-desmethyl analogue 155. Unfortunately, initial efforts failed to resolve 155 into its two optical isomers with cellulose triacetate.92 However, the antimalarial activity of racemate 155 is intriguing, as discussed in a later section. 

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