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Alternating Copolymers Via Diels-Alder and Ene Reactions

Abstract

4-Phenyl-l,2,4-triazoline-3,5-dione, 1, is an extremely reactive dienophile1–9 and enophile6,9 that is at least 1000 times more reactive in the Diels-Alder reaction with 2-chlorobutadiene than tetracyanoethylene (TCNE) and 2000 times more reactive than maleic anhydride. 4-Methyl-1,2,4-triazoline-3,5-dione, 2, is at least 30,000 times more reactive towards cyclohexene than its open chain analog, ethylazodicarboxylate.6 The many reactions of these powerful electron-acceptor molecules are generally quite rapid, being complete within a matter of seconds within the range of 0°C to room temperature.