Chemical Synthesis of Cyclodextrins

Several chemical syntheses of cyclodextrins have recently been developed. Although the syntheses are usually long, with many steps, and have low yields, a number of unusual and heretofore unknown cyclodextrins have been obtained. 

The total synthesis of cylomaltohexaose (a-cyclodextrin) has been achieved starting with maltose. Maltose derivatives were condensed two times to give the key intermediate 2,3,6-octa-o-benzyl-P-maltohexaosyl fluoride, which was cy- 

The total synthesis of cyclomaltooctaose (7-cyclodextrin) has been achieved in a similar manner in 21 steps from maltose with an overall yield of 0.02% [62]. A similar synthesis was also conducted to form a hexasaccharide that was cyclized to give an a-1 - 6 linkage and the formation of an isomer of cyclomaltohexaose with one a-1 6 linkage and five a-1 4 linkages in the ring [62]. Specific in- 

Another cyclomaltohexaose isomer was synthesized in which the D-glucose residues were replaced by D-mannose residues [63,64]. The key intermediate was the formation of a mannohexaosyl methylthioglycoside that was cyclized by an intramolecular glycosylation reaction using phenylselenyl triflate as a catalyst. 

The synthesis of p-1 — 3-linked cyclo-D-glucohexaose was achieved by using l,2-o-benzilidene-4,6-ethylidene-a-D-glucopyranose and the formation of 2-o-benzoyl-4,6-ethylidene-D-glucopyranosyl bromide by photobromination. This brontide was sequentially condensed to give a p-1 3-linked-a-hexaosyl bromide, which was cyclized by silver triflate catalyst to produce the protected 3-1 — 3 cyclolaminarihexaose [65]. 

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Wakao, M, K Fukase and S Kusumoto (2002). Chemical synthesis of cyclodextrins by using intramolecular glycosylation. Journal of Organic Chemistry, 67,8182-8190. 

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