Synthesis Of Single-hydroxy-¦Á-cyclodextrin Derivatives With High Spatial Region

In this paper, mono hydroxyl a-CDs ether derivatives were synthesized byfacile approach. In the process of alkylation of the primely side of Hexaki(2,3-di-O-benzyl)-α-CD(4), we could directly get the high yield of 6^{Ⅰ-Ⅴ}-Hexa-O-pentylenyl-2^{Ⅰ-Ⅵ},3^{Ⅰ-Ⅵ}-di-O-benzyl-a-CD(6e) from controlling the amounts of the catalyst NaH and5-bromo-1-pentene. While the ratio of 4:NaH:RBr was 1:14:24, the yield of 6eincreased even up to 70% and the yield of Hexaki[(6-O-(pentylenyl-1)-2,3-di-O-benzyl]-α-CD (5e)decreased. However, the yield of 5e and 6e would decrease whenonly amounts of bromides were increased without the increase of NaH. Then a seriesof alkyl bromide were used instead of 5-bromo-l-pentene to proceed the similaralkylation. As a result, while using bromoethane, 3-bromo-l-propylene, only thecomplete alkylation ofα-CDs were obtained. While using 1-bromopropane,1-bromobutane and 1-bromopentane, similar phenomenon could be seen as5-bromo-l-pentene. While using 1-bromohexane, three different alkylatedα-CDswere obtained. The reason is that as the number of carbon atoms increase, on onehand, the volume of alkyl bromide would be larger, so is the steric hindrance, on theother hand, the eletrophilicity and acidity of alkyl bromide would decrease. Thisregioselective reaction didn't need protection and deprotection steps and had highyield of mono hydroxylα-CDs ether derivatives. The derivatives would be convenientto give further modification of the monohydroxy group which had not been replaced.