(Z)-4-(2,5-Di-tert-butyl­anilino)pent-3-en-2-one

Jesús Pastrán; Andrea Ramírez; Giuseppe Agrifoglio; Anthony Linden; Romano Dorta

doi:10.1107/S1600536811017296

. 2011 May 14;67(Pt 6):o1405–o1406. doi: 10.1107/S1600536811017296

(Z)-4-(2,5-Di-tert-butylanilino)pent-3-en-2-one

Jesús Pastrán ^a, Andrea Ramírez ^a, Giuseppe Agrifoglio ^a, Anthony Linden ^b,^*, Romano Dorta ^a,^*

PMCID: PMC3120447 PMID: 21754790

Abstract

In the crystal structure of the title ketoamine, C₁₉H₂₉NO, the bond lengths from the N atom through the alkene group to the ketone O atom show the presence of an extensively delocalized π-system. The dihedral angle between the plane of the phenyl ring and that of the alkene component is 63.45 (7)° due to steric hindrance exerted by the tert-butyl groups. The molecule has a Z-configured alkene function, which is facilitated by an intramolecular N—H⋯O hydrogen bond between the amine and ketone groups. The molecules are linked into extended chains, which run parallel to the [010] direction, by a very weak C—H⋯O interaction between the methyl substituent of the alkene group and the ketone O atom of a neighbouring molecule.

Related literature

For the conformations of β-ketoamines, see: Pastrán et al. (2011 ▶); Zharkova et al. (2009 ▶). For reactions involving aminoketonate complexes, see: He et al. (2003 ▶); Hsu, Chang et al. (2004 ▶); Lai et al. (2005 ▶); Li et al. (2005 ▶); Tang et al. (2005 ▶); Hsu, Li et al. (2007 ▶); Pan et al. (2008 ▶). For the preparation and coordination chemistry of aminoketonate ligands, see: Jones et al. (1998 ▶); Shukla et al. (2005 ▶); Lesikar et al. (2008 ▶); Sedai et al. (2008 ▶).

Experimental

Crystal data

C₁₉H₂₉NO
M _r = 287.44
Monoclinic,
a = 23.7759 (5) Å
b = 9.0517 (2) Å
c = 19.3760 (4) Å
β = 120.6308 (11)°
V = 3588.11 (13) Å³
Z = 8
Mo Kα radiation
μ = 0.06 mm⁻¹
T = 160 K
0.32 × 0.25 × 0.20 mm

Data collection

Nonius KappaCCD area-detector diffractometer
24643 measured reflections
3153 independent reflections
2769 reflections with I > 2σ(I)
R _int = 0.035

Refinement

R[F ² > 2σ(F ²)] = 0.044
wR(F ²) = 0.118
S = 1.04
3152 reflections
203 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.19 e Å⁻³
Δρ_min = −0.17 e Å⁻³

Data collection: COLLECT (Nonius, 2000 ▶); cell refinement: DENZO-SMN (Otwinowski & Minor, 1997 ▶); data reduction: DENZO-SMN and SCALEPACK (Otwinowski & Minor, 1997 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEPII (Johnson, 1976 ▶); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536811017296/lh5243sup1.cif

e-67-o1405-sup1.cif^{(26.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811017296/lh5243Isup2.hkl

e-67-o1405-Isup2.hkl^{(154.7KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536811017296/lh5243Isup3.cdx

Supplementary material file. DOI: 10.1107/S1600536811017296/lh5243Isup4.cml

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
N15—H15⋯O18	0.908 (17)	1.848 (17)	2.6376 (15)	144.1 (15)
C20—H201⋯O18ⁱ	0.98	2.52	3.474 (2)	164

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Symmetry code: (i) Inline graphic .

Acknowledgments

This work was financed by FONACIT (project S1–2001000851).

supplementary crystallographic information

Comment

Anions of β-amino-α-enones are potentially useful bidentate ligands (Jones, et al., 1998; Shukla, et al., 2005; Hsu, Li et al., 2007; Lesikar, et al., 2008; Sedai, et al., 2008) in stoichiometric (Hsu, Chang et al., 2004) and catalytic processes (He, et al., 2003; Lai, et al., 2005; Li, et al., 2005; Tang, et al., 2005; Pan, et al., 2008). Generally, β-amino-α-enones have Z conformations that are stabilized by intramolecular hydrogen bonds (Zharkova, et al., 2009; Pastrán et al., 2011). The title β-amino-α-enone was derived from 2,5-di-tert-butyl-aniline and acetylacetone, via the 4-[(-)1-phenyl-ethylamino]-pent-3-en-2-one intermediate (Lai, et al., 2005). In its crystal structure, the plane of the aryl ring is twisted out of the plane spanned by the C═C double bond (defined by atoms N15, C16, C17, C18 and C20) by 63.45 (7)° due to the steric pressure exerted by the tert-butyl groups (Fig. 1). The bond lengths from N15 through the alkene group to the ketone O atom, O18, show the presence of an extensively delocalized π-system (Table 1). Even the C1—N15 bond is shorter than a normal single bond, despite the twist about this bond. The Z-configuration of the molecule facilitates the formation of an intramolecular N—H···O hydrogen bond between the amine group and the carbonyl O-atom (Table 2). The molecules are linked into extended 2₁-symmetrical chains, which run parallel to the [010] direction, by a very weak C—H···O interaction between the methyl substituent of the alkene group and the ketone O atom of a neighbouring molecule. There are no other significant intermolecular interactions in the structure.

Experimental

The title compound was prepared by refluxing 2,5-di-tert-butyl-aniline (1.14 g, 5.56 mmol) with 4-[(-)1-phenyl-ethylamino]-pent-3-en-2-one (Lai, et al., 2005) (1.14 g, 5.60 mmol) in dry ethanol (30 ml) and HCl (12M, 0.5 ml) for 24 h. The cooled reaction mixture was treated with 1M K₂CO₃ and extracted with CH₂Cl₂ (3 × 10 ml). The extracts were dried over MgSO₄, filtered, and the volatiles evaporated in vacuo to afford an orange oil. Methanol (2.0 ml) was added and the resulting solution was cooled to 273 K for two days to yield 0.50 g (37%) of colorless crystals (m.p. 325–327 K). ¹H-NMR (400 MHz, CDCl₃): δ 1.28 (s, 9H), 1.35 (s, 9H), 1.79 (s, 3H), 2.10 (s, 3H), 5.22 (s, 1H), 7.35–6.97 (m, 3H), 12.48 (s, 1H).