4-(6-Benzyl-7-oxo-1,2,3,4,5,5a,5a1,6,7,7a,8,12b-dodecahydrobenzo[f]cycloocta[cd]isoindol-8-yl)benzonitrile

In the title compound, C31H30N2O, the cis-fused cyclohexene and cyclooctane rings adopt boat and boat-chair conformations, respectively. The essentially planar five-membered N-heterocyclic ring [r.m.s. deviation = 0.017 (1) Å] is cis- and trans-fused, respectively, with the cyclohexene and cyclooctane rings. In the crystal, molecules are linked into inversion dimers through pairs of weak C—H⋯O interactions.

In the title compound, C 31 H 30 N 2 O, the cis-fused cyclohexene and cyclooctane rings adopt boat and boat-chair conformations, respectively. The essentially planar five-membered Nheterocyclic ring [r.m.s. deviation = 0.017 (1) Å ] is cis-and trans-fused, respectively, with the cyclohexene and cyclooctane rings. In the crystal, molecules are linked into inversion dimers through pairs of weak C-HÁ Á ÁO interactions.

Related literature
For the atom economy and environmental benefits of using a domino reaction to construct a structurally complicated molecule, see: Zhao et al. (2012). For palladium-catalysed coupling reactions, see: Hu et al. (2009Hu et al. ( , 2010. For the use of condensed heterocyclic compounds as synthetic building blocks, pharmacophores and electroluminescent materials, see: Rixson et al. (2012). For reactions of aryl halides with olefins, see: Yu & Hu (2012); Wang & Hu (2011 Table 1 Hydrogen-bond geometry (Å , ).

Yu-Long Zhang and Yi-Min Hu Comment
Domino reaction as an efficient protocol to construct structurally complicate molecule due to high atom economy and environmental benefits (Zhao et al., 2012). Palladium-catalyzed domino reactions have become an important tool of modern organic synthesis chemistry (Hu et al., 2009(Hu et al., , 2010. Condensed heterocyclic compounds are playing increasingly important roles as synthetic building blocks, pharmacophores, and electroluminescence materials (Rixson et al., 2012).
We have reported some novel intermolecular and intramolecular reactions of aryl halides with the olefins (Yu et al., 2012;Wang et al., 2011). The reaction of 4-bromobenzonitrile with N-benzyl-N-(cyclooct-2-en-1-yl) cinnamamide, in the presence of palladium(II) acetate and triphenylphosphine, in DMF at 423 K for 18 h, gave the unexpected title product.
The title compound, C 31 H 30 N 2 O, contains three phenyl ring, one five-numbered N-heterocyclic ring, one six-membered carbon ring with a boat conformation, and one eight-memmbered carbon ring with a boat-chair conformation. All the rings are not coplanar (Fig. 1). In the molecule there are five chiral carbon atoms, C8, C14, C15, C16 and C18, but the crystal is a racemic system due to lacking of the chiral separation. In the crystal packing, there are weak intermolecular C -H···O interactions, C29-H29···O1 i (i: -x, 1 -y, 1 -z), through which dimers were formed between paired enantiomers ( Fig. 2).

Experimental
An oven-dried Schlenk flask was evacuated, filled with nitrogen, and then charged with N-benzyl-N-(cyclooct-2-en-1yl)cinnamamide (3.45 g, 10 mmol), ethyl 4-bromobenzonitrile (2.01 g, 11 mmol), tributylamine (3 ml), PPh 3 (52.5 mg, 0.2 mmol), Pd(OAc) 2 (24 mg, 0.1 mol), and DMF (10 ml) to give a yellow solution. The reaction mixture was heated at 423 K with stirring. The reaction mixture was cooled to room temperature after 18 h and the resultant yellow-orange mixture was diluted with Et 2 O (10 ml). The mixture was washed with H 2 O (15 ml) and the aqueous layer was extracted with Et 2 O (20 ml). The combined organic layers were dried (MgSO 4 ), filtered, and concentrated in vacuo. The crude material was purified by flash column chromatography on silica gel (petroleum ester:EtOAc, 8:1) and recrystallized from EtOAc, yield 3.48 g (78%). Colorless crystals suitable for X-ray diffraction were obtained by recrystallization from a solution of the title compound from ethyl acetate over a period of one week.

Refinement
H atoms were positioned geometrically and refined using a riding model with C-H = 0.93-0.97 Å, and with U iso (H) = 1.2U eq (C).