Regiospecific A,B Capping onto β-Cyclodextrin. Characteristic Remote Substituent Effect on 13C NMR Chemical Shift and Specific Taka-amylase Hydrolysis

Article abstract of DOI:10.1021/jo00215a008

A,B-regiospecific (97percent A,B and 3percent A,C) capping of β cyclodextrin was first achieved by the use of m-benzenedisulfonyl chloride.The A,B regiochemistry is ascertained by a remarkable effect of a remote substituent of ring A on the high-field 13C NMR chemical shift of ring B.Further support for the A,B structure is obtained by its specific hydrolysis to disubstituted fragmental sugars catalyzed by Taka-amylase.The novel cap was converted to a series of A,B-disubstituted β-cyclodextrins-diiodo, dideoxy, bis(butylsulfenyl), bis(phenylsulfenyl), andbis((p-tert-butylphenyl)sulfenyl).Characteristic remote chemical shifts in 100 MHz 13C NMR were observed for these A,B derivatives, the C₆, C₄, and C₁ shifts of which were extremely useful for the differentiation of an A,B regioisomer from other regioisomers.Noteworthy is the remarkable chemical shift difference thus produced between C₆, C₄, and C₁ on the A ring and C₆, C₄, and C₁ on the B ring, providing an interesting possibility of spectroscopic determination of clockwise and counterclockwise A,B structure.