One‐pot synthesis of polysaccharide 3,5‐dimethylphenylcarbamates having a random vinyl group for immobilization on silica gel as chiral stationary phases

Abstract

Different kinds of vinyl groups were randomly introduced onto the glucose units of cellulose 3,5-dimethylphenylcarbamates by a one-pot method using the bifunctional reagents dec-1-ene-10-isocyanate, 2-isocyanatoethyl methacrylate, and methacryloyl chloride. The chiral recognition properties of the prepared derivatives were then evaluated by coating and immobilizing them on silica gel as HPLC packing material. Immobilization was carried out by radical copolymerization with a vinyl comonomer, 1,5-hexadiene, in toluene at 80 degrees C. The effects of the structures and content of the vinyl groups on the immobilization and on enantioseparations were investigated. This one-pot method was also extended to the synthesis of amylose 3,5-dimethylphenylcarbamates having a random vinyl group. Comparisons of the chiral resolution powers of our laboratory-made packing materials and the newly commercialized Chiralpak IA with immobilized amylose 3,5-dimethylphenylcarbamate and Chiralpak IB with immobilized cellulose 3,5-dimethylphenylcarbamate are discussed.

Immobilized-type chiral packing materials for HPLC based on polysaccharide derivatives

“…This regioselective immobilization method may not be appropriate for the large-scale preparation of the CPMs. On the other hand, the simple preparation of immobilized-type CPMs can be achieved using the polysaccharide derivatives bearing vinyl groups nonregioselectively at the 2-, 3-and 6-positions [84,87].…”

“…2) [73]. Since then, we have been exploring the optimum preparation conditions for the immobilized-type CPM by changing the type and amount of the vinyl monomer or the vinyl group introduced to the polysaccharide derivatives and also by introducing a vinyl group on the silica surface as follows [72,74,[84][85][86][87][88][89].…”

“…7) and immobilized onto the MA-silica (see Fig. 5) via the copolymerization with 1,5-hexadiene in toluene at 80 • C [87]. The immobilization efficiencies and the chiral recognitions of the immobilized-type CPMs are listed in Table 3.…”

“…The amylose 3,5-dimethylphenylcarbamate (18) bearing the 10% methacrylate group (R 4 ) non-regioselectively at the 2-, 3-and 6-positions has been prepared by the one-pot method (Fig. 7) [87]. The derivative 18 was immobilized onto the MA-silica under the same radical polymerization condition as applied to the cellulose derivative 15.…”

“…The immobilization of amylose derivatives bearing a vinyl group onto the silica gel is also possible [85,87]. The amylose 3,5-dimethylphenylcarbamate (18) bearing the 10% methacrylate group (R 4 ) non-regioselectively at the 2-, 3-and 6-positions has been prepared by the one-pot method (Fig.…”