Ethyl (1R,1′S,2′S,7aR)-2-oxo-1′-[(3aR,5R,5aS,8aS,8bR)-2, 2,7,7-tetra-methyltetrahydro-3aH-bis[1,3]dioxolo[4,5-b:4′,5′-d] pyran-5-yl]-1′,2′,5′,6′,7′,7a-hexahydro-2H-spiro- [acenaphthyl-ene-1,3′-pyrrolizine]-2′-carboxylate

Abstract

In the title compound, C 32H 37NO 8, the central pyran ring adopts a twistboat conformation and the 1,3-dioxoane rings adopt envelope conformations. The acenaphthylenone unit and two C atoms of a pyrrolidine ring are disordered over two sets of sites [occupancy ratio 0.669 (7):0.331 (7)]. The major fraction of the disordered pyrrolidine ring exhibits an envelope conformation while the minor component is essentially planar [maximum deviation = 0.037 (12) Å]. The other pyrrolidine ring also adopts an envelope conformation. The dihedral angle between the mean planes of the two wings of the pyrrolidine ring is 30.6 (2)°. Both the major and minor components of the acenaphthylenone unit are essentially planar, the maximum deviations being 0.025 (10) and 0.047 (19) Å, respectively; the dihedral angle between the mean planes of the two components is 1.72 (3)°. The crystal packing features C - H⋯O interactions.