N-[2-Methyl-1-(2-naphthyl)­propenyl]­acet­amide

The crystal structure determination of the title compound, C₁₆H₁₇NO, establishes that the en­amide moiety in the mol­ecule exists as the NH tautomer.

Key indicators

• Single-crystal X-ray study
• T = 294 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.035
• wR factor = 0.065
• Data-to-parameter ratio = 11.0

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



ABSMU_01  Alert C The ratio of given/expected absorption coefficient lies
          outside the range 0.99 <> 1.01
          Calculated value of mu =     0.072
          Value of mu given      =     0.070

General Notes



REFLT_03
         From the CIF: _diffrn_reflns_theta_max           27.60
         From the CIF: _reflns_number_total               1823
         Count of symmetry unique reflns         1835
         Completeness (_total/calc)             99.35%
         TEST3: Check Friedels for noncentro structure
         Estimate of Friedel pairs measured         0
         Fraction of Friedel pairs measured     0.000
         Are heavy atom types Z>Si present           no
          Please check that the estimate of the number of Friedel pairs is
          correct. If it is not, please give the correct count in the
          _publ_section_exptl_refinement section of the submitted CIF.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

---

S1. Comment

The title compound, N-[2-methyl-1-(2-naphthyl)propenyl]acetamide, (I), is one of the prochiral olefinic substrates for producing chiral amines by asymmetric hydrogenation (Zhang et al., 1998; Burk et al., 1998). The e.e.'s of the chiral amine, the product of asymmetric hydrogenation, were significantly influenced by the solvent owing to the presence of different concentrations of the NH tautomer (Li et al., 2000; Yan et al., 2000). Much effort has been devoted to the development of new and efficient chiral species for hydrogenation of this kind of substrate. In this study, the structure determination of the title compound was conducted in order to obtain more knowledge about enamide compounds.

The crystal structure (Fig. 1) shows that the N1—C15 bond of 1.341 (3) Å is shorter than the N1—C11 bond of 1.436 (3) Å. This is consistent with the presence of the NH tautomer for the enamide moiety. The C10—C1—C11—C12, C15—N1—-C11–C12 and C10—C1—C11—N1 torsion angles are -131.4 (3), 78.0 (3) and 49.4 (3)°, respectively. These show that the C11═C12 double bond is not in the same plane as either the naphthyl ring or the amide group, and so the C11═C12 double bond does not conjugate with either of these. The reason for this phenomenon is likely due to the hindrance that would occur in a planar arrangement, involving the C13 and C14 methyl groups. Atom H1A on the amine atom N1 forms an intermolecular hydrogen bond with atom O1 of another molecule at (-1/2 + x, 3/2 - y, 1 - z), with an N1···O1 distance of 2.852 (3) Å and an angle at H1A of 168°. As illustrated in Fig. 2, these interactions link the molecules in chains along the a axis.

S2. Experimental

To a 100 ml nitrogen-flushed three-neck round-bottomed flask, the Grignard reagent (ⁱPrMgBr, 15 mmol) in THF (15 ml) was added. 2-Naphthonitrile (10 mmol) in THF (10 ml) was added dropwise and the solution allowed to stir overnight under N₂ at room temperature. Acetic anhydride (30 mmol) was added dropwise and the mixture allowed to reflux for 20 min. Slow addition of excess methanol (15 ml) followed. The solution was transferred to a separating funnel, water was added, then the aqueous mixture was extracted with ethyl acetate (EA; 3 × 30 ml). The organic layer was dried with anhydrous Na₂SO₄ and then removed under reduced pressure. The crude product was purified by chromatography with appropriate mixture of hexane and ethyl acetate as eluent. A crystal suitable for X-ray analysis was grown slowly in mixed solvent (EA–hexane = 1/5) at room temperature. ¹H NMR (500 MHz, CDCl₃, Varian): (rotamer of enamide = 2:1) δ 1.78 (s, 1H), 1.86 (s, 4H), 1.92 (s, 1H), 1.95 (s, 1H), 2.10 (s, 2H), 7.39–7.51 (m, 3H), 7.72–7.82 (m, 4H); N—H resonance: 6.58 (s, 0.67H), 6.75 (s, 0.33H),

S3. Refinement

H atoms were included in the riding model approximation with U_iso equal to U_eq of the atom to which they were bound. The absolute structure was not determined unambiguously.

Computing details

Data collection: SMART (Siemens, 1995); cell refinement: SAINT (Bruker, 2000); data reduction: SHELXTL-NT (Siemens, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL-NT; software used to prepare material for publication: SHELXTL-NT.

Figures

Fig. 1. The molecular structure of (I) showing ellipsoids at the 30% probability level (Bruker, 1995).

N-[2-methyl-1-(2-naphthyl)propenyl]acetamide

Crystal data

C16H17NO	Dx = 1.153 Mg m^−3
Mr = 239.31	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121	Cell parameters from 2387 reflections
a = 8.9766 (14) Å	θ = 1–27.5°
b = 12.3744 (19) Å	µ = 0.07 mm^−1
c = 12.4145 (18) Å	T = 294 K
V = 1379.0 (4) Å^3	Needle, colorless
Z = 4	0.38 × 0.10 × 0.10 mm
F(000) = 512

Data collection

Bruker CCD area-detector diffractometer	1823 independent reflections
Radiation source: fine-focus sealed tube	828 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.072
ϕ and ω scans	θmax = 27.6°, θmin = 3.3°
Absorption correction: empirical (using intensity measurements) (SADABS; Sheldrick, 1996)	h = −11→11
Tmin = 0.973, Tmax = 0.993	k = −16→14
9481 measured reflections	l = −14→16

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.065	H-atom parameters constrained
S = 0.94	w = 1/[σ^2(Fo^2) + (0.015P)^2] where P = (Fo^2 + 2Fc^2)/3
1823 reflections	(Δ/σ)max < 0.001
166 parameters	Δρmax = 0.10 e Å^−3
0 restraints	Δρmin = −0.10 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

The sample is a small needle crystal. diffraction intensities is lower and cause The amount of observed data is lower.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.4357 (2)	0.67851 (15)	0.49420 (15)	0.0796 (6)
N1	0.2095 (2)	0.72939 (16)	0.43428 (15)	0.0601 (6)
H1A	0.1294	0.7645	0.4492	0.072*
C1	0.2496 (3)	0.7499 (2)	0.24112 (18)	0.0536 (6)
C2	0.1689 (3)	0.7496 (2)	0.14753 (19)	0.0605 (7)
H2A	0.0888	0.7024	0.1416	0.073*
C3	0.2021 (3)	0.8177 (2)	0.0599 (2)	0.0565 (7)
C4	0.1207 (3)	0.8155 (2)	−0.0374 (2)	0.0704 (8)
H4A	0.0397	0.7690	−0.0440	0.084*
C5	0.1584 (4)	0.8793 (3)	−0.1208 (2)	0.0831 (9)
H5A	0.1034	0.8766	−0.1842	0.100*
C6	0.2783 (4)	0.9491 (3)	−0.1129 (2)	0.0858 (9)
H6A	0.3047	0.9914	−0.1718	0.103*
C7	0.3581 (3)	0.9565 (2)	−0.0200 (2)	0.0724 (8)
H7A	0.4363	1.0056	−0.0149	0.087*
C8	0.3225 (3)	0.8899 (2)	0.0688 (2)	0.0589 (7)
C9	0.4010 (3)	0.8934 (2)	0.1664 (2)	0.0667 (8)
H9A	0.4770	0.9438	0.1750	0.080*
C10	0.3684 (3)	0.8249 (2)	0.2489 (2)	0.0656 (8)
H10A	0.4252	0.8273	0.3115	0.079*
C11	0.2185 (3)	0.6760 (2)	0.33180 (19)	0.0546 (7)
C12	0.1977 (3)	0.5698 (2)	0.3247 (2)	0.0662 (7)
C13	0.2180 (4)	0.5066 (2)	0.22083 (18)	0.0902 (10)
H13A	0.2714	0.5500	0.1697	0.135*
H13B	0.1222	0.4881	0.1919	0.135*
H13C	0.2733	0.4418	0.2353	0.135*
C14	0.1606 (3)	0.5007 (2)	0.4207 (2)	0.0966 (10)
H14A	0.1307	0.5461	0.4796	0.145*
H14B	0.2466	0.4595	0.4413	0.145*
H14C	0.0807	0.4525	0.4026	0.145*
C15	0.3184 (3)	0.7280 (2)	0.5082 (2)	0.0613 (7)
C16	0.2898 (3)	0.7921 (2)	0.60835 (17)	0.0756 (8)
H16A	0.3324	0.7554	0.6691	0.113*
H16D	0.1844	0.7998	0.6188	0.113*
H16C	0.3344	0.8623	0.6014	0.113*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0576 (12)	0.0929 (15)	0.0883 (14)	0.0165 (12)	−0.0198 (12)	−0.0209 (12)
N1	0.0499 (13)	0.0758 (16)	0.0546 (12)	0.0046 (12)	0.0001 (12)	−0.0094 (12)
C1	0.0522 (17)	0.0568 (17)	0.0519 (16)	0.0014 (16)	0.0016 (13)	−0.0091 (14)
C2	0.0558 (17)	0.0689 (18)	0.0568 (17)	−0.0107 (16)	−0.0007 (14)	−0.0067 (15)
C3	0.0584 (18)	0.0579 (18)	0.0532 (16)	−0.0009 (16)	0.0019 (15)	−0.0062 (14)
C4	0.074 (2)	0.076 (2)	0.0616 (19)	−0.0017 (17)	−0.0053 (17)	−0.0010 (16)
C5	0.094 (3)	0.093 (2)	0.0618 (19)	0.007 (2)	−0.0044 (19)	0.0071 (19)
C6	0.100 (3)	0.079 (2)	0.078 (2)	0.014 (2)	0.015 (2)	0.0137 (18)
C7	0.076 (2)	0.063 (2)	0.079 (2)	0.0013 (16)	0.0146 (18)	0.0046 (17)
C8	0.0579 (19)	0.0592 (18)	0.0597 (18)	0.0021 (16)	0.0085 (15)	−0.0055 (15)
C9	0.064 (2)	0.0615 (19)	0.0747 (19)	−0.0115 (16)	0.0045 (17)	−0.0086 (17)
C10	0.0614 (19)	0.074 (2)	0.0614 (18)	−0.0032 (18)	−0.0020 (15)	−0.0129 (16)
C11	0.0476 (16)	0.0651 (19)	0.0510 (16)	−0.0003 (16)	−0.0062 (14)	−0.0054 (16)
C12	0.0619 (19)	0.070 (2)	0.0670 (17)	−0.0036 (17)	−0.0092 (15)	−0.0003 (16)
C13	0.114 (3)	0.073 (2)	0.083 (2)	0.003 (2)	−0.024 (2)	−0.0194 (16)
C14	0.107 (3)	0.088 (2)	0.094 (2)	−0.023 (2)	−0.013 (2)	0.0185 (18)
C15	0.0596 (18)	0.066 (2)	0.0578 (17)	−0.0008 (17)	−0.0041 (17)	−0.0046 (15)
C16	0.081 (2)	0.088 (2)	0.0581 (15)	0.0032 (18)	−0.0061 (16)	−0.0122 (15)

Geometric parameters (Å, º)

O1—C15	1.230 (3)	C7—H7A	0.9300
N1—C15	1.341 (3)	C8—C9	1.402 (3)
N1—C11	1.436 (3)	C9—C10	1.362 (3)
N1—H1A	0.8600	C9—H9A	0.9300
C1—C2	1.369 (3)	C10—H10A	0.9300
C1—C10	1.417 (3)	C11—C12	1.331 (3)
C1—C11	1.477 (3)	C12—C14	1.504 (3)
C2—C3	1.408 (3)	C12—C13	1.519 (3)
C2—H2A	0.9300	C13—H13A	0.9600
C3—C8	1.406 (3)	C13—H13B	0.9600
C3—C4	1.413 (3)	C13—H13C	0.9600
C4—C5	1.346 (3)	C14—H14A	0.9600
C4—H4A	0.9300	C14—H14B	0.9600
C5—C6	1.383 (4)	C14—H14C	0.9600
C5—H5A	0.9300	C15—C16	1.497 (3)
C6—C7	1.361 (3)	C16—H16A	0.9600
C6—H6A	0.9300	C16—H16D	0.9600
C7—C8	1.414 (3)	C16—H16C	0.9600
C15—N1—C11	124.0 (2)	C9—C10—C1	121.2 (2)
C15—N1—H1A	118.0	C9—C10—H10A	119.4
C11—N1—H1A	118.0	C1—C10—H10A	119.4
C2—C1—C10	117.2 (2)	C12—C11—N1	120.3 (2)
C2—C1—C11	123.0 (2)	C12—C11—C1	126.0 (2)
C10—C1—C11	119.7 (2)	N1—C11—C1	113.6 (2)
C1—C2—C3	122.8 (2)	C11—C12—C14	122.7 (2)
C1—C2—H2A	118.6	C11—C12—C13	123.2 (2)
C3—C2—H2A	118.6	C14—C12—C13	114.0 (2)
C8—C3—C2	118.8 (2)	C12—C13—H13A	109.5
C8—C3—C4	118.5 (3)	C12—C13—H13B	109.5
C2—C3—C4	122.6 (3)	H13A—C13—H13B	109.5
C5—C4—C3	121.1 (3)	C12—C13—H13C	109.5
C5—C4—H4A	119.5	H13A—C13—H13C	109.5
C3—C4—H4A	119.5	H13B—C13—H13C	109.5
C4—C5—C6	120.5 (3)	C12—C14—H14A	109.5
C4—C5—H5A	119.7	C12—C14—H14B	109.5
C6—C5—H5A	119.7	H14A—C14—H14B	109.5
C7—C6—C5	120.8 (3)	C12—C14—H14C	109.5
C7—C6—H6A	119.6	H14A—C14—H14C	109.5
C5—C6—H6A	119.6	H14B—C14—H14C	109.5
C6—C7—C8	120.1 (3)	O1—C15—N1	122.3 (2)
C6—C7—H7A	119.9	O1—C15—C16	121.9 (2)
C8—C7—H7A	119.9	N1—C15—C16	115.9 (2)
C9—C8—C3	118.3 (2)	C15—C16—H16A	109.5
C9—C8—C7	122.8 (3)	C15—C16—H16D	109.5
C3—C8—C7	118.9 (3)	H16A—C16—H16D	109.5
C10—C9—C8	121.5 (3)	C15—C16—H16C	109.5
C10—C9—H9A	119.3	H16A—C16—H16C	109.5
C8—C9—H9A	119.3	H16D—C16—H16C	109.5
C10—C1—C2—C3	1.7 (4)	C7—C8—C9—C10	−177.0 (2)
C11—C1—C2—C3	−177.8 (2)	C8—C9—C10—C1	−2.7 (4)
C1—C2—C3—C8	−0.5 (4)	C2—C1—C10—C9	−0.1 (4)
C1—C2—C3—C4	178.5 (2)	C11—C1—C10—C9	179.4 (2)
C8—C3—C4—C5	1.1 (4)	C15—N1—C11—C12	78.0 (3)
C2—C3—C4—C5	−177.9 (3)	C15—N1—C11—C1	−102.8 (3)
C3—C4—C5—C6	0.0 (5)	C2—C1—C11—C12	48.1 (4)
C4—C5—C6—C7	−1.7 (5)	C10—C1—C11—C12	−131.4 (3)
C5—C6—C7—C8	2.3 (4)	C2—C1—C11—N1	−131.2 (2)
C2—C3—C8—C9	−2.3 (3)	C10—C1—C11—N1	49.4 (3)
C4—C3—C8—C9	178.7 (2)	N1—C11—C12—C14	1.6 (4)
C2—C3—C8—C7	178.6 (2)	C1—C11—C12—C14	−177.5 (3)
C4—C3—C8—C7	−0.5 (4)	N1—C11—C12—C13	−174.8 (2)
C6—C7—C8—C9	179.7 (3)	C1—C11—C12—C13	6.0 (5)
C6—C7—C8—C3	−1.2 (4)	C11—N1—C15—O1	−1.1 (4)
C3—C8—C9—C10	3.9 (4)	C11—N1—C15—C16	177.8 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O1^i	0.86	2.00	2.852 (3)	168

Symmetry code: (i) x−1/2, −y+3/2, −z+1.