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

nzoyl)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. [6-O-(tert.-butyl)dimethylsilyl]-b eta-cyclodextrin was regioselectively monoesterified with p-allyloxybe nzoyl chloride or p-(tert.-butyl)benzoyl chloride to yield 2-O-(p-ally loxybenzoyl) [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 p-allyloxybenzoyl)he ptakis(3-O-acetyl-6-O-methyl)- (D),2(E),2(F),2(G)-hexa-O-acetyl-beta-c yclodextrin (10). Both 6 and 7 were methylated, following by deprotect ion 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 w as transformed into permethylated 2(A)-O-(p-allyloxybenzyl)-beta-cyclo dextrin (18) by a nucleophilic substitution reaction. Four new permeth yl- or per(methyl/acetyl)-substituted beta-cyclodextrin-bound methylpo lysiloxanes were prepared by a hydrosilylation reaction of the monoalk enyl-substituted beta-cyclodextrin derivatives 4, 10, 15 and 18 with a specially prepared hydromethylpolysiloxane. The polymeric phases prov ide excellent enantiomeric separations of a variety of chiral solutes in open tubular column supercritical fluid chromatography and gas chro matography.