IMDAV reaction between phenyl­maleic anhydride and thien­yl(fur­yl)allyl­amines: synthesis and mol­ecular structure of (3aSR,4RS,4aRS,7aSR)-5-oxothieno- and (3aSR,4SR,4aRS,7aSR)-5-oxofuro[2,3-f]iso­indole-4-carb­oxy­lic acids

The title compounds C(24)H(21)NO(3)S, I, and C(24)H(21)NO(4), II, are the products of the IMDAV reaction between phenyl­maleic anhydride and thien­yl(fur­yl)allyl­amines. Their mol­ecular structures comprise fused tricyclic systems containing thio­phene, cyclo­hexene and pyrrolidine rings (I) or furan, cyclo­hexene and pyrrolidine rings (II). The central cyclo­hexene and pyrrolidine rings in both compounds adopt slightly twisted boat and envelope conformations, respectively. The dihedral angles between the basal plane of the pyrrolidine ring and the thio­phene (in I) or furan (in II) ring plane are 22.74 (16) and 26.29 (5)°, respectively. The nitro­gen atom both in I and II has practically planar environment [the sums of the bond angles are 359.8 and 358.9°, respectively]. In the crystal of I, the mol­ecules form hydrogen-bonded zigzag chains along [010] through strong inter­molecular O—H⋯O hydrogen bonds involving carb­oxy­lic and keto groups, whereas in the crystal of II, the mol­ecules are joined into centrosymmetric dimers by strong O—H⋯O hydrogen bonds between the carb­oxy­lic groups. In II, the atoms involved into these hydrogen bonds (and hence the whole carb­oxy­lic group) are disordered over two sets of sites with an occupancy ratio of 0.6:0.4. Compounds I and II crystallize as racemates consisting of enanti­omeric pairs of the 3aSR,4RS,4aRS,7aSR and 3aSR,4SR,4aRS,7aSR diastereomers, respectively.