REGIOSELECTIVITY OF ALKYLATION OF CYCLOMALTOHEPTAOSE (BETA-CYCLODEXTRIN) AND SYNTHESIS OF ITS MONO-2-O-METHYL, MONO-2-O-ETHYL, MONO-2-O-ALLYL, AND MONO-2-O-PROPYL DERIVATIVES
J. Jindrich et al., REGIOSELECTIVITY OF ALKYLATION OF CYCLOMALTOHEPTAOSE (BETA-CYCLODEXTRIN) AND SYNTHESIS OF ITS MONO-2-O-METHYL, MONO-2-O-ETHYL, MONO-2-O-ALLYL, AND MONO-2-O-PROPYL DERIVATIVES, Carbohydrate research, 266(1), 1995, pp. 75-80
Mono-2-O-methyl-, -2-O-ethyl-, and -2-O-allyl-cyclomaltoheptaose were
prepared by alkylations of cyclomaltoheptaose in dilute aqueous alkali
, and mono-2-O-propylcyclomaltoheptaose was obtained by hydrogenation
of the allyl derivative. Ah the 2-O-alkyl derivatives were less solubl
e in water than was cyclomaltoheptaose. All formed inclusion complexes
with toluene in aqueous solution, but only the methyl ether was less
soluble in the water-toluene system than in water. The solubilities of
the other ethers in water were enhanced by the addition of toluene. P
artial methylation of cyclomaltoheptaose with C-13-enriched dimethyl s
ulfate in dilute aqueous alkali yielded mixtures of products. The subs
titution patterns were analyzed by GLC-MS of the alditol acetates, pre
pared by hydrolysis, reduction, and acetylation, and by C-13 NMR after
complete permethylation with nonenriched reagent. The results showed
that methylation at O-2 is a predominant but not an exclusive reaction
; as expected, the regioselectivity decreases with increasing degree o
f methylation.