Cyclodextrin Methacrylate via Microwave-Assisted Click Reaction

Click reaction of propargyl methacrylate (1) with 6I-azido-6I-deoxycyclomaltoheptaose (2) was carried out to synthesize mono-(1H-1,2,3-triazol-4-yl)(methyl)2-methylacryl-beta-cyclodextrin (3). The process was investigated by varying the reaction time, temperature profiles, and copper catalyst. Microwave irradiation was compared with conventional heating. The microwave-assisted Cu(I)-catalyzed cycloaddition affords the complete conversion of (2) into 1,4-disubstituted triazole in a significant decreased reaction time. Under microwave conditions, the cycloaddition of (2) onto poly(propargyl methacrylate) (5) was conducted in excellent yields. The regioselectivity of click reactions in dependence of reaction conditions was evaluated by use of NMR spectroscopy. The reactions performed under microwave conditions led exclusively to 1,4-disubstituted triazole, while the conventional heating led to a regioisomeric mixture.