(S)-(−)-2-(1H-Indol-3-yl)-N-(1-phenyl­eth­yl)acetamide

Johana Ramírez; Oscar Romero; Jorge R Juárez; Joel L Terán; Angel Mendoza

doi:10.1107/S1600536812028450

. 2012 Jun 30;68(Pt 7):o2252. doi: 10.1107/S1600536812028450

(S)-(−)-2-(1H-Indol-3-yl)-N-(1-phenylethyl)acetamide

Johana Ramírez ^a, Oscar Romero ^a, Jorge R Juárez ^a, Joel L Terán ^a, Angel Mendoza ^a,^*

PMCID: PMC3394039 PMID: 22798904

Abstract

In the title compound, C₁₈H₁₈N₂O, the dihedral angle between the indole system and the phenyl ring is 17.2 (2)°. The crystal packing features two N—H⋯O hydrogen bonds, which link the molecules into layers parallel to (001). The absolute configuration was determined by the synthetic procedure and was set according to the starting material.

Related literature

For background to the synthesis of chiral non-racemic acetamide indole compounds, see: Kochanowska-Karamyan & Hamann (2010 ▶). For their use in the synthesis of nitrogen heterocyclic compounds and indole alkaloids, see: Suárez-Castillo et al. (2006 ▶); Chiou et al. (2009 ▶).

Experimental

Crystal data

C₁₈H₁₈N₂O
M _r = 278.34
Orthorhombic,
a = 7.307 (4) Å
b = 8.559 (4) Å
c = 25.674 (9) Å
V = 1605.7 (13) Å³
Z = 4
Mo Kα radiation
μ = 0.07 mm⁻¹
T = 298 K
0.65 × 0.6 × 0.1 mm

Data collection

Siemens P4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.646, T _max = 1
2937 measured reflections
2126 independent reflections
1146 reflections with I > 2σ(I)
R _int = 0.045
3 standard reflections every 97 reflections intensity decay: 1%

Refinement

R[F ² > 2σ(F ²)] = 0.065
wR(F ²) = 0.161
S = 1.05
2126 reflections
199 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.15 e Å⁻³
Δρ_min = −0.15 e Å⁻³

Data collection: XSCANS (Siemens, 1994 ▶); cell refinement: XSCANS; data reduction: XSCANS; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 (Farrugia, 1997 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812028450/bt5951sup1.cif

e-68-o2252-sup1.cif^{(18.1KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812028450/bt5951Isup2.hkl

e-68-o2252-Isup2.hkl^{(102.4KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812028450/bt5951Isup3.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
N1—H1N⋯O1ⁱ	0.89 (5)	2.03 (5)	2.891 (4)	163 (4)
N2—H2N⋯O1ⁱⁱ	0.96 (6)	1.91 (6)	2.847 (5)	164 (4)

Open in a new tab

Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

We are grateful for financial support by projects VIEP-BUAP and CONACyT CB-2009–01/128747. JR and OR thank CONACyT for doctoral scholarships. Special thanks go to Dr Marcos Flores-Alamo (USAI/FQ/UNAM) for useful comments.

supplementary crystallographic information

Comment

The synthesis of chiral non racemic acetamides indole compounds is an original area of interest in organic chemistry (Kochanowska-Karamyan & Hamann, 2010) because they are useful intermediates for the synthesis of diverse interesting nitrogen heterocyclic compounds and indole alkaloids derivatives and natural products (Suárez-Castillo et al., 2006; Chiou et al., 2009).

In the title compound the N1 atom in a planar conformation from the plane between C9, H1N and C1 with an r.m.s. deviation of 0.012Å. The N1—C9 [1.322 (5) Å] and C9—O1 [1.254 (4) Å] distances show electron delocalization along the N1—C9—O1 system. The indole group shows a torsion angle of 102.1 (4)° from the plane placed by N1/C9/C10/C11 and phenyl ring C2—C7 shows a torsion angle of 92.3 (4)° from plane C9/N1/C1/C2. The crystal packing is stabilized by two hydrogen bond interactions [N1—H1N···O1 and N2—H2N···O1] linking the molecules into planes parallel to (0 0 1) (Table 1).

Experimental

The title compound, C₁₈H₁₈N₂O, was obtained dissolving indolic acid (0.96 mmol, 0.277 g) and boric acid (0.30 mmol, 0.020 g) in 88 ml of toluene under N₂ atmosphere. Once the mixture was colorless, (S)-(-)-phenylethylamine was added and heated under reflux by 16 h. After that, mixture was cooled and hexane (0.5 L) was added. Finally, white solid was obtained and crystalized from an ethyl acetate/diethylether solution; m. p. 94–96 °C. [α]_D²⁵ = -45.7° (c 1.5, CH₂Cl₂); IR (KBr)1643 cm^{-1. 1}H NMR (CDCl₃, 400 MHz) δ (p.p.m.), J(Hz) 9.24 (s, 1H), 7.48 (d, J=8.0, 1H),7.26 (d, J=8.4, 1H), 7.17–7.05 (m, 6H),6.85 (d, J=2.4, 1H), 6.32 (d, J=8.0, 1H), 5.12 (m, 1H), 3.69 (d, J=3.2, 2H), 1.24 (d, J=7.2, 3H). ¹³C NMR (CDCl₃,100 MHz) δ (p.p.m.) 22.2, 33.8, 49.1, 108.2,112.1, 118.8–128.8, 136.9, 143.4, 171.8.