Imino(dialkylamino)isoindolines: Structures and dynamic behavior

In 1956, Elvidge and coworkers investigated the synthesis of a series of isoindoline compounds derived from phthalonitrile. They produced a series of secondary amine-modified isoindolines known as the imino(dialkylamino)isoindolines, and in this report, we revisit this chemistry. In addition to confirming the previously observed reactivity, we structurally characterized three examples and observed a double bond character between the isoindoline carbon atom and the secondary nitrogen atom position. This results in a rotational barrier about this bond, which we observed by NMR spectroscopy and probed using computational methods. The barriers are comparable to those seen in bis-substituted amides.