One-pot synthesis of new iso-DPP derivatives from terminal alkynes and isocyanates

[Display omitted] •A new route to novel derivatives of the iso-DPP ring system is reported.•By changing the conditions, 5-ylidenepyrrol-2(5H)-ones can also be accessed.•Crystal structures of both heterocycles have been determined.•The reagents are cheap and readily available and the process is operationally simple. The reaction of phenyl acetylide anion with aryl isocyanates followed by quenching with water is shown to produce pyrrolopyrrole (iso-DPP) derivatives in addition to the isomeric cyclopentadienone imines previously reported. If the reaction is quenched with dilute HCl, 5-ylidenepyrrol-2(5H)-ones, formed by a Meyer-Schuster rearrangement, can be isolated instead. A possible mechanism for this reaction is suggested.