点击化学法快速合成氨基酸功能化的环糊精聚轮烷

通过叠氮-炔环加成点击反应制备了各种氨基酸功能化的生物相容性β-环糊精封端的α-环糊精聚轮烷.利用FTIR和氢核磁共振谱对产物的结构进行了表征.结果证明对于空间位阻较小的分子,点击反应能够在很短的时间(几分钟)内达到近100%的转化率.点击化学为功能化聚轮烷的制备提供了快速有效的新途径.

FACILE FUNCTIONALIZATION OF POLYROTAXANES VIA CLICK CHEMISTRY

The Cu (I)-catalyzed"click"reaction of azides and alkynes was selected as the coupling reaction to prepare a novel biocompatible polyrotaxane (PR) conjugate,which was composed of azido-functionalized PR backbone (Mn = 1. 35 × 105 ) based on α-cyclodextrins ( α-CDs) /poly ( ethylene glycol) ( PEG) inclusion complex and amino acids protected by tert-butyloxycarbonyl ( Boc ) groups,that is,Boc-Gly-OH,Boc-Lys (Boc)-OH,and Boc-Phe-OH. The alkynyl groups were introduced into the aforementioned amino acids via N, N-dicyclohexylcarbodiimide (DCC) /4-(dimethylamino)pyridine ( DMAP ) condensation with propargyl alcohol. The click coupling reaction was demonstrated to be extremely efficient,and high conversion of azido groups,approximate 100% ,was achieved in a short reaction time (within several minutes) in the cases of Boc- Gly-OH and Boc-Lys(Boc)-OH. As to the bulky Boc-Phe-OH,only part of the azido groups of the backbone was converted though the coupling reaction time was prolonged (3 h). The corresponding amino acids-PR conjugates were soluble in a wide variety of organic solvents,such as N,N-dimethylformamide,acetone,ethanol and so forth. GPC was utilized to measure the molecular weight of Boc-Lys( Boc)-PR conjugates ( PR-Lys), and the result was Mn = 1. 66 × 105(Mw /Mn = 1. 57),much smaller than the theoretical ones. This might be resulted from the compactly packed conformation of PR-Lys. The warm-like morphology of PR-Lys was observed via AFM. Other alkyne-functionalized compounds involving 4-( 2-azidoethoxy)-4-oxobutanoic acid and propargyl alcohol were also attached to the PR backbone successfully. This click strategy would be a promising general method for the functionalization of PRs.