“…The C1-C2-C3-C4 torsion angle in (I) [33.88 (9) ] is very close to that in (II) [38.6 (3) ]. The relevant bond lengths of this fragment in (I) and (II) are not significantly different, except for the N2-C1 bond, which is about 0.02 Å shorter in (II) than in (I), and they are typical of other pyrrolidone-containing compounds, (X)-(XV) (Scheme 3; Derricott, 1980;Soriano-García et al, 1986;Mü ller et al, 1996;Hollenberg et al, 1997;Wang et al, 2006;Herler et al, 2007) (see Table 3).…”