LARGE-RIM-TETHERED PERMETHYL-SUBSTITUTED BETA-CYCLODEXTRIN POLYSILOXANES FOR USE AS CHIRAL STATIONARY PHASES IN OPEN-TUBULAR COLUMN CHROMATOGRAPHY

3-O-(p-Allyloxybenzoyl)hepatkis(2,6-di-O-methyl)-beta-cyclodextrin, which was used for preparation of permethylated 3-O-(p-allyloxybenzoyl)-beta-cyclodextrin (4), was produced in a 15% yield by a monoesterification of heptakis(2,6-di-O-methyl)-beta-cyclodextrin. Heptakis[6-O-(tert.-butyl)dimethylsilyl]-beta-cyclodextrin was regioselectively monoesterified with p-allyloxybenzoyl chloride or p-(tert.-butyl)benzoyl chloride to yield 2-O-(p-allyloxybenzoyl) heptakis[6-O-(tert.-butyl)dimethylsilyl]-beta-cyclodextrin (6) or 2-O-[p-(tert.-butyl)benzoyl]heptakis[6-O-(tert. -butyl)dimethylsilyl]-beta-cyclodextrin (7). Compound 6 was acylated to give tridecaacetate 8, which was deprotected and methylated, to give 2(A)-O-(p-allyloxybenzoyl)heptakis(3-O-acetyl-6-O-methyl)- 2(B),2(C),2(D),2(E),2(F),2(G)-hexa-O-acetyl-beta-cyclodextrin (10). Both 6 and 7 were methylated, following by deprotection and methylation (on the 6-position), to give permethylated 2(A)-O-(p-allyloxybenzoyl)-beta-cyclodextrin (15) and permethylated 2(A)-O-[p-(tert.-butyl)benzoyl]-beta-cyclodextrin (16), respectively. Then, 16 was treated with lithium aluminum hydride to form monoalcohol, which was transformed into permethylated 2(A)-O-(p-allyloxybenzyl)-beta-cyclodextrin (18) by a nucleophilic substitution reaction. Four new permethyl- or per(methyl/acetyl)-substituted beta-cyclodextrin-bound methylpolysiloxanes were prepared by a hydrosilylation reaction of the monoalkenyl-substituted beta-cyclodextrin derivatives 4, 10, 15 and 18 with a specially prepared hydromethylpolysiloxane. The polymeric phases provide excellent enantiomeric separations of a variety of chiral solutes in open tubular column supercritical fluid chromatography and gas chromatography.