Download PDF Opens in a new window. Article suggestions will be shown in a dialog on return to ScienceDirect. ... Please enable JavaScript to use all the features on this page. ... Spiro 2-pyrrolidin-5-ones were obtained from N-substituted succinimides by a two-step procedure, involving 5- or 6-endo-trig cyclisation of N-acyliminium ion intermediates with a tethered aromatic π-nucleophile. ... Spiro 2-pyrrolidin-5-ones were obtained from N-substituted ...