Crystal structures and conformational analyses of three pyranochromene derivatives

Abstract

In the crystal structures of the three title pyran–chromene derivatives, (I)–(III), mol­ecules are linked by C—H⋯O hydrogen bonds which generate mol­ecular sheets parallel to the ab plane with (28) loops in (I), inversion dimers with (10) loops in (II) and chains along the b axis with (12) ring motifs in (III).

Methyl (6R*,6aR*,12bR*)-2,4-dimethyl-6-(2-methylphenyl)-1,3-dioxo-2,3,4,6a,7,12b-hexahydro-1H,6H-chromeno[4′,3′:4,5]pyrano[2,3-d]pyrimidine-6a-carboxylate

“…data reports C12(position 6a) and C6(position 12b), respectively (see Scheme). The bond distances and bond angles are in good agreement with the values reported for similar structures (Swaminathan et al, 2015;Ponnusamy et al, 2013). The sp 2 hybridization of atoms N1 and N2 are indicated by the sum of the bond angles of 359.8 and 360.0 , respectively.…”

“…The title compound was synthesized following a published procedure (Ponnusamy et al, 2013;Swaminathan et al, 2015). A mixture of (E)-methyl 2-((2-formylphenoxy)methyl)-3-(2methylphenyl) acrylate (0.448 g, 1 mmol) and N,N-dimethylbarbutric acid (0.156 g, 1 mmol) was placed in a round-bottom flask and melted at 453 K for 1 h. After completion of the reaction, as indicated by TLC, the crude product was washed with 5 ml of an ethylacetate and hexane mixture (1:49) which successfully provided the pure title compound as a colourless solid in 97% yield.…”