The crystal structures and Hirshfeld surface analysis of 6-(naphthalen-1-yl)-6a-nitro-6,6a,6b,7,9,11a-hexa­hydro­spiro­[chromeno[3′,4′:3,4]pyrrolo­[1,2-c]thia­zole-11,11′-indeno­[1,2-b]quinoxaline] and 6′-(naphthalen-1-yl)-6a′-nitro-6′,6a′,6b′,7′,8′,9′,10′,12a′-octa­hydro-2H-spiro­[ace­naphthyl­ene-1,12′-chromeno[3,4-a]indolizin]-2-one

The crystal structures of the title spiro derivatives are described and the analysis of the inter­molecular contacts in the crystals using Hirshfeld surface analysis and two-dimensional fingerprint plots is reported. The title compounds, 6-(naphthalen-1-yl)-6a-nitro-6,6a,6 b,7,9,11 a -hexa­hydro­spiro­[chromeno[3′,4′:3,4]pyrrolo­[1,2- c ]thia­zole-11,11′-indeno­[1,2- b ]quinoxaline], C 37 H 26 N 4 O 3 S, (I), and 6′-(naphthalen-1-yl)-6a′-nitro-6′,6a′,6b′,7′,8′,9′,10′,12 a ′-octa­hydro-2 H -spiro­[ace­naphthyl­ene-1,12′-chromeno[3,4- a ]indolizin]-2-one, C 36 H 28 N 2 O 4 , (II), are new spiro derivatives, in which both the pyrrolidine rings adopt twisted conformations. In (I), the five-membered thia­zole ring adopts an envelope conformation, while the eight-membered pyrrolidine-thia­zole ring adopts a boat conformation. An intra­molecular C—H⋯N hydrogen bond occurs, involving a C atom of the pyran ring and an N atom of the pyrazine ring. In (II), the six-membered piperidine ring adopts a chair conformation. An intra­molecular C—H⋯O hydrogen bond occurs, involving a C atom of the pyrrolidine ring and the keto O atom. For both compounds, the crystal structure is stabilized by inter­molecular C—H⋯O hydrogen bonds. In (I), the C—H⋯O hydrogen bonds link adjacent mol­ecules, forming R 2 2 (16) loops propagating along the b -axis direction, while in (II) they form zigzag chains along the b -axis direction. In both compounds, C—H⋯π inter­actions help to consolidate the structure, but no significant π–π inter­actions with centroid–centroid distances of less than 4 Å are observed.