In the course of a study on pyrrolidinones, the crystal structures of four
compounds, namely, methyl N-[(4-methoxyphenyl)(3,4,5-trimethoxyphenyl)methy
l]pyroglutamate, C23H27NO7, methyl N-[naphthyl-(3,4,5-trimethoxyphenyl)meth
yl]pyroglutamate diacetyl peroxide, C26H27NO6.-0.5C(4)H(6)O(4), 5-(3,4,5-tr
imethoxyphenyl)-1,2,3,11b-tetrahydro-5H-naphtho[1,8-f,g]indolizin-3-one C24
H23NO4, and 5-(3,4,5-trimethoxyphenyl)-1,2,3,5,12,12a-hexahydronaphtho[1,2-
f]indolizine-3,12-dione, C25H23NO5, are presented, compared and discussed.