2,4,6,8-Tetra­kis(4-ethyl­phen­yl)-3,7-diaza­bicyclo­[3.3.1]nonan-9-one

K Rajesh; V Vijayakumar; A P Safwan; Kong Wai Tan; Edward R T Tiekink

doi:10.1107/S1600536810016569

. 2010 May 12;66(Pt 6):o1316. doi: 10.1107/S1600536810016569

2,4,6,8-Tetrakis(4-ethylphenyl)-3,7-diazabicyclo[3.3.1]nonan-9-one

K Rajesh ^a, V Vijayakumar ^a,^‡, A P Safwan ^b, Kong Wai Tan ^b, Edward R T Tiekink ^b,^*

PMCID: PMC2979421 PMID: 21579409

Abstract

The bicyclo[3.3.1]nonane ring in the title compound, C₃₉H₄₄N₂O, adopts a chair–boat conformation with the four benzene rings being directed away from the carbonyl group. The presence of C—H⋯O contacts leads to helical supramolecular chains along the b axis.

Related literature

For background to the synthesis and stereochemistry of 3,7-diazabicyclo[3.3.1]nonan-9-ones and their derivatives, see: Srikrishna & Vijaykumar (1998 ▶); Pathak et al. (2007 ▶); Vijayakumar & Sundaravadivelu (2005 ▶). For related structures, see: Natarajan et al. (2008 ▶); Fun et al. (2009 ▶). For conformational analysis, see: Cremer & Pople (1975 ▶).

Experimental

Crystal data

C₃₉H₄₄N₂O
M _r = 556.76
Monoclinic,
a = 13.381 (2) Å
b = 11.8217 (17) Å
c = 19.989 (3) Å
β = 99.675 (4)°
V = 3117.1 (8) Å³
Z = 4
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 100 K
0.40 × 0.37 × 0.29 mm

Data collection

Bruker SMART APEX diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.972, T _max = 0.980
29235 measured reflections
7159 independent reflections
5783 reflections with I > 2σ(I)
R _int = 0.033

Refinement

R[F ² > 2σ(F ²)] = 0.042
wR(F ²) = 0.117
S = 1.03
7159 reflections
389 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.27 e Å⁻³

Data collection: APEX2 (Bruker, 2008 ▶); cell refinement: SAINT (Bruker, 2008 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and DIAMOND (Brandenburg, 2006 ▶); software used to prepare material for publication: publCIF (Westrip, 2010 ▶).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810016569/hg2681sup1.cif

e-66-o1316-sup1.cif^{(29.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810016569/hg2681Isup2.hkl

e-66-o1316-Isup2.hkl^{(343.2KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C26—H26⋯O1ⁱ	0.95	2.51	3.3837 (16)	153

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Symmetry code: (i) Inline graphic .

Acknowledgments

VV is grateful to DST India for funding through the Young Scientist Scheme (Fast Track Proposal).

supplementary crystallographic information

Comment

The synthesis and stereochemistry of 3,7-diazabicyclo[3.3.1]nonan-9-ones and their derivatives are of much interest owing to their diverse biological activities (Srikrishna & Vijaykumar, 1998; Pathak et al., 2007). The conformational analysis of 3,7-diazabicyclo[3.3.1]nonanes (bispidines) is of interest from a theoretical view point and in particular the 2,4,6,8-tetraaryl-3,7-diazabicyclo[3.3.1]nonanes constitute an interesting case for study owing to the presence of four aryl groups (Vijayakumar & Sundaravadivelu, 2005). If all aryl groups occupy equatorial orientations, molecular models indicate their close proximity to both rings in the bicyclic systems. By contrast, if they are in the twin chair conformation, severe non-bonded interactions arise between aryl groups occupying 2,8-positions and 4,6-positions. In the present report, in continuation of studies in this area (Natarajan et al., 2008; Fun et al., 2009), the synthesis and structure determination of a new example, the title compound (I), is described.

In (I), the bicyclo[3.3.1]nonane ring adopts a chair-boat conformation with ring puckering amplitudes (Cremer & Pople, 1975) for the N1-containing ring (chair) being Q = 0.6318 (13) Å, θ = 6.38 (11) ° and φ = 183.5 (11) °. For the N2-ring, which adopts the boat form, the equivalent parameters are 0.8044 (12) Å, 88.29 (9) °, and 358.47 (9) °, respectively. The benzene rings adjacent to the N1 atom are each directed away from the carbonyl group and are effectively co-planar [dihedral angle = 6.91 (6) °]. The arrangement defines a planar facade to this side of the molecule, especially considering the ethyl groups are folded back to be orientated toward the rest of the molecule. By contrast, the benzene rings adjacent to the N2 atom are somewhat splayed with adjacent benzene rings forming dihedral angles of 54.17 (6) ° [(C8–C13)/(C16–C21)] and 48.45 (6) ° [(C24–C29)/(C32–C37)]. The dihedral angle between the (C16–C21) and (C24–C29) rings is 38.01 (6) ° so as to define a concave facade to this part of the molecule; the ethyl groups for these benzene rings are directed away from the molecule.

Despite there being two acidic N—H H atoms in the structure, neither play a significant role in the crystal packing owing to steric congestion. Rather, the carbonyl group participates in a C–H···O contact, Table 1, to generate a supramolecular chain with helical topology along the b axis, Fig. 2.

Experimental

A mixture of acetone (0.2 ml), 4-ethylbenzaldehyde (2 ml) and dry ammonium acetate (0.6 g) were taken in a 1:4:2 molar ratio in ethanol (15 ml) and the resulting solution heated on water bath till the colour changed to red-orange. The mixture was allowed to stand for 24 h. The resultant sticky precipitate was washed with a mixture of diethyl ether and ethanol (4:1). The solid obtained was crystallized from a mixture of CHCl₃-methanol (1:1) to yield (I). M.Pt: 495–497 K.