K. Bynum, Ron Prip, R. Callahan
Jun 26, 1998
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Influential Citations
12
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Journal
Journal of Fluorine Chemistry
Abstract
Abstract N-pentafluorophenyl maleimide acts as an efficient Diels-Alder dienophile to form an adduct with phencyclone. The adduct was found to exhibit five distinct 19F NMR signals (282 MHz, ambient temperature, CDCl6) consisting of two gross doublets and three gross triplets. We interpret this as consistent with a severely hindered rotation about the N-C6F5 bond in the adduct, leading to a slow exchange limit (SEL) spectrum. The C6F5 group is thought to lie, on average, on the effective mirror plane of the adduct, perpendicular to the pyrrolidinedione ring system, to reduce steric interactions of the ortho fluorines with the imide N(CO)2 carbonyls. 19F-19F COSY45 NMR allowed assignment of vicinal fluorines in the C6F5. Comparative data is presented for the precursors, N-pentafluorophenyl maleamic acid and N-pentafluorophenyl maleimide. Variable temperature 19F NMR results for the maleamic acid are presented.