Crystal structure and Hirshfeld surface analysis of dieth-yl (3aS,3a1R,4S,5S,6R,6aS,7R,9aS)-3a1,5,6,6a-tetra-hydro-1H,3H,4H,7H-3a,6:7,9a-di-epoxy-benzo[de]isochromene-4,5-di-carboxyl-ate

In the title compound, C18H22O7, two hexane rings and an oxane ring are fused together. The two hexane rings tend toward a distorted boat conformation, while the tetra-hydro-furan and di-hydro-furan rings adopt envelope conformations. The oxane ring is puckered. The crystal structure features C-H⋯O hydrogen bonds, which link the mol-ecules into a three-dimensional network. According to a Hirshfeld surface study, H⋯H (60.3%) and O⋯H/H⋯O (35.3%) inter-actions are the most significant contributors to the crystal packing.

Crystal engineering of molecules with through-space α-effect hydrogen bonds: 3a,6 : 7,9a-diepoxybenzo[de]isoquinolines possessing a free amino group

The existence of a “through-space” alpha-effect is analyzed in all-cis 3a,6 : 4,5 : 7,9a-triepoxy and 3a,6 : 7,9a-diepoxybenzo[de]isoquinolines. It is demonstrated that the H-bonds are enhanced by the α-effect.