Methyl 4-(4-methoxyphenyl)-1,2,3,3a,4,4a,5,12c-octahydrobenzo[f]chromeno[3,4-b]pyrrolizine-4a-carboxylate

In the title compound, C27H27NO4, both the pyrrolidine rings in the pyrrolizine ring system adopt envelope conformations, whereas the dihydropyran ring adopts a half-chair conformation. The methoxyphenyl group is oriented at an angle of 53.72 (4)° with respect to the naphthalene ring system. Intramolecular C—H⋯O hydrogen bonds are observed. The crystal structure is stabilized by weak intermolecular C—H⋯π interactions.

In the title compound, C 27 H 27 NO 4 , both the pyrrolidine rings in the pyrrolizine ring system adopt envelope conformations, whereas the dihydropyran ring adopts a half-chair conformation. The methoxyphenyl group is oriented at an angle of 53.72 (4) with respect to the naphthalene ring system. Intramolecular C-HÁ Á ÁO hydrogen bonds are observed. The crystal structure is stabilized by weak intermolecular C-HÁ Á Á interactions.

Related literature
For the biological activity of pyrrolizine derivatives, see: Amal Raj et al. (2003); Atal (1978); Denny (2001); Suzuki et al. (1994). For a related structure, see: Ramesh et al. (2007). For ring-puckering parameters, see: Cremer & Pople (1975 Table 1 Hydrogen-bond geometry (Å , ). Methyl 4-(4-methoxyphenyl)-1,2, 3,3a,4,4a,5,12c-octahydrobenzo[f]chromeno[3,4-b]pyrrolizine-4acarboxylate S. Nirmala, E. T. S. Kamala, L. Sudha, S. Kathiravan and R. Raghunathan Comment Pyrrolizidine alkaloids occur in more than 40 genera, and are responsible for heavy losses of livestock and poisoning in man due to their hepatotoxity. These alkaloids are also reported to possess a number of other biological activities (Atal, 1978) and are used as DNA minor groove alkylating agents (Denny, 2001). Substituted pyrrolidines have gained much importance because they are the structural elements of many alkaloids. It has been found that they exhibit antifungal activity against various pathogens (Amal Raj et al., 2003). Optically active pyrrolidine derivatives have been used as intermediates in controlled asymmetric synthesis (Suzuki et al., 1994). In view of its biological importance, the crystal structure determination of the title compound was undertaken.
A displacement ellipsoid plot of the title compound is shown in Fig. 1. The pyrrolizine ring system is folded about the bridging N1-C15 bond, as observed in related structures (Ramesh et al., 2007). The sum of bond angles around atom N1 [337.9 (7)°] is in accordance with sp 3 hybridization. The napthalene ring system C2-C11 and the methoxyphenyl group  , 1975) respectively. In the ring N1/C1/C13-C15, atom C13 deviates by 0.547 (8) Å from the least-square plane through the remaining four atoms, whereas in the ring N1/C15-C18, atom C17 deviates by -0.616 (4) Å from the least-squares plane through the remaining four atoms.

Experimental
A mixture of (Z)-methyl-2-((1-formylnaphthalen-2-yloxy)methyl)-3-(4-methoxyphenyl) acrylate (20 mmol) and proline (30 mmol) were refluxed in benzene for 20 h and the solvent was removed under reduced pressure. The crude product was subjected to column chromatography to get the pure product. A chloroform and methanol (1:1) solvent mixture was used for the crystallization using the slow evaporation method.
supplementary materials sup-2 Refinement H atoms were placed in idealized positions and allowed to ride on their parent atoms, with C-H = 0.93, 0.98, 0.97 and 0.96 Å for aromatic, methine, methylene and methyl H respectively, and Uiso(H) = 1.5U eq (C) for methyl H and Uiso(H) = 1.2U eq (C) for all other H atoms. Fig. 1. The molecular structure of the title compound, with 30% probability displacement ellipsoids.