Synthesis and X-Ray Crystal Structure of Two Acridinedione Derivatives

The two acridinedione derivatives 1 [3,3,6,6-tetramethyl-9-(4-methoxyphenyl)-3,4,6,7,9,10-hexahydro-2H,5H-acridine-1,8-dione (C24H29NO3)] and 2 [3,3,6,6-tetramethyl-9-(4-methylphenyl)-3,4,6,7,9,10-hexa-hydro-2H,5H-acridine-1,8-dione (C24H29NO2)] were synthesized and their crystal structures were determined by direct methods. The asymmetric unit of compound 1 contains two independent molecules. The 1,4-dihydropyridine (DHP) ring adopts boat conformation in both 1 and 2. In 1 the dione rings exist in sofa conformation (for both the crystallographically independent molecules) while the corresponding rings in 2 adopt half chair and sofa conformations, respectively. The crystal packing is stabilized by intermolecular N–H⋯O and C–H⋯O interactions in compound 1 and N–H⋯O interactions in compound 2.