Ciclodextrinas
Mono-modification at the C6-Position
Mono-6-tosylatedb-CyD:
The reaction of b-CyD with tosyl chloride in aqueous alkaline medium gives mono-6-tosylated b-CyD in fairly good yield (Takahashi K, Hattori K, Toda F, Tetrahedron Lett. 1984, 25, 3331–1334.)The first pathway has already been reported as the method for attaching a tosyl residue at the primary C-6 hydroxyl group of the CD moiety which was treated with 1.8 eq. of tosyl chloride in drypyridine at 5OC for 5 hr.
The second pathway was treated with 6 eq. of tosyl chroride and CD in an monotosylation of alkaline aqueous solution (pH 13) at room temperature for 1 hr. As this reactionproceeded it was accompanied by a 1:l complex formation between tosyl chloride both a- and B-CD were modified on primary hydroxyl position of glucose C-6.
In the DMF-buffer condition, both a- and B-CD weremodified at the C-2 position stereospecifically.
Mono-6-azide b-CyD:
A direct azidation of CyDs with sodium azide in the presence of triphenylphosphine–carbon tetrabromide has also beenreported (Jimenez-Blanco JL, Garcia-Fernandez JM, Gadelle A, Defaye J,Carbohydr. Res. 1997, 303, 367–372.)
General procedure for the preparation of sugar azides.--Typically, a 1 : 1.1:1.1:5 sugar...
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