Crystal structures of the two epimers from the unusual thermal C6-epimerization of 5-oxo-1,2,3,5,5a,6,7,9b-octahydro-7,9a-epoxypyrrolo[2,1-a]isoindole-6-carboxylic acid, 5a(RS),6(SR),7(RS),9a(SR),9b(SR) and 5a(RS),6(RS),7(RS),9a(SR),9b(SR)

Acta Crystallographica Section E: Crystallographic Communications

Victor N. Khrustalev¹  Yan V. Zubavichus²  Pavel V. Dorovatovskii²  Dmitry S. Poplevin³  Fedor I. Zubkov³ 

[1] Inorganic Chemistry Department, Peoples' Friendship University of Russia (RUDN University), 6 Miklukho-Maklay St., Moscow 117198, Russian Federation;National Research Centre "Kurchatov Institute", 1 Acad. Kurchatov Sq., Moscow 123182, Russian Federation;Organic Chemistry Department, Peoples' Friendship University of Russia (RUDN University), 6 Miklukho-Maklay St., Moscow 117198, Russian Federation;

关键词: intramolecular Diels–Alder furan (IMDAF) reaction;    azaheterocycles;    epimerization;    tautomerism;    crystal structure;   

DOI  :  10.1107/S2056989016014420

来源: DOAJ

【 摘 要 】

The isomeric title compounds, C12H13NO4 (Ia) and C12H13NO4 (IIa), the products of an usual thermal C6-epimerization of 5-oxo-1,2,3,5,5a,6,7,9b-octahydro-7,9a-epoxypyrrolo[2,1-a]isoindole-6-carboxylic acid, represent the two different diastereomers and have very similar molecular geometries. The molecules of both compounds comprise a fused tetracyclic system containing four five-membered rings (pyrrolidine, pyrrolidinone, dihydrofuran and tetrahydrofuran), all of which adopt the usual envelope conformations. The dihedral angle between the basal planes of the pyrrolidine and pyrrolidinone rings are 14.3 (2) and 16.50 (11)°, respectively, for (Ia) and (IIa). The nitrogen atom has a slightly pyramidalized geometry [bond-angle sum = 355.9 and 355.3°, for (Ia) and (IIa)], respectively. In the crystal of (Ia), molecules form zigzag-like hydrogen-bonded chains along [010] through strong O—H...O hydrogen bonds and are further linked by weak C—H...O hydrogen bonds into complex two-tier layers parallel to (100). Unlike (Ia), the crystal of (IIa) contains centrosymmetric cyclic hydrogen-bonded dimers [graph set R22(14)], formed through strong O—H...O hydrogen bonds and are further linked by weak C—H...O hydrogen bonds into ribbons extending across [101].

【 授权许可】

Unknown