Ethyl 2-amino-4-isobutyl­thio­phene-3-carboxyl­ate

The title compound, C₁₁H₁₇NO₂S, was synthesized by the Gewald reaction. Intra­molecular N—H...O and C—H...O hydrogen bonds determine the conformation of the mol­ecule. The packing of the mol­ecules in the crystal structure is governed mainly by inter­molecular N—H...O hydrogen-bonding inter­actions.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.005 Å
• R factor = 0.070
• wR factor = 0.172
• Data-to-parameter ratio = 17.0

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT220_ALERT_2_C Large Non-Solvent    C     Ueq(max)/Ueq(min) ...       2.75 Ratio
PLAT242_ALERT_2_C Check Low       Ueq as Compared to Neighbors for         C6
PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor ....       2.03
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          5

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   5 ALERT level C = Check and explain
   1 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 ALERT type 3 Indicator that the structure quality may be low
   0 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

The chemistry of 2-aminothiophenes has received much attention because of the convenient availability through the most versatile synthetic methods developed by Gewald (Sabnis et al., 1999). Recently we have been interested in the synthesis of derivatives of heterocycles using the aza-Wittig reaction. Some related X-ray crystal structure reports for pyrimidinone derivatives have been published (Ding et al., 2004; Liu & Hu, 2006; Liu & Liao, 2006). Here, the structure of the title compound, which may be used as a new intermediate synthesized via the Gewald reaction, is reported (Fig. 1). The thiophene ring system is coplanar. Intramolecular N—H···O and C—H···O hydrogen bonds (Table 1) determine the conformation of the molecule. As can be seen from the packing diagram (Fig. 2), intramolecular and intermolecular N—H···O hydrogen bonds (Table 1) link the molecules.

Related literature

A related synthetic method is described by Sabnis et al. (1999). For related literature, see: Ding et al. (2004); Liu & Hu (2006); Liu & Liao (2006).

S2. Experimental

To a solution of ethyl cyanoacetate(1.13 g, 10 mmol), sulfur (0.32 g, 10 mmol) and 4-methylpentan-2-one (1.00 g, 10 mmol) in anhydrous ethanol (20 ml) was added in morpholine (0.8 ml). The mixture was stirred for 6 h at 313 - 323 K. The solution was concentrated under reduced pressure and the residue was recrystallized from dichloromethane and ethanol (1:2 v/v) to give the title compound. Crystals suitable for single-crystal X-ray diffraction were obtained by recrystallization from a mixed solvent of ethanol and dichloromethane (1:1 v/v) at room temperature.

S3. Refinement

All H atoms were located in difference maps and treated as riding atoms, except those at N1, with the following distance restraints: C—H = 0.93 Å, U_iso=1.2U_eq (C) for Csp², C—H = 0.98 Å, U_iso = 1.2U_eq (C) for CH, C—H = 0.97 Å, U_iso = 1.2U_eq (C) for CH₂, N—H = 0.86 Å, U_iso = 1.2U_eq (N) for NH₂, C—H = 0.96 Å, U_iso = 1.5U_eq (C) for CH₃.

Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT-Plus (Bruker, 2001); data reduction: SAINT-Plus (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXTL (Sheldrick, 2001).

Figures

	Fig. 1. A view of the title compound showing the atom-labeling scheme. Displacement ellipsoids are drawn at the 50% probability level, intramolecular hydrogen bonds are shown in dashed lines.
	Fig. 2. The packing in the crystal structure, showing the N—H···O hydrogen bonds as dashed lines.

Ethyl 2-amino-4-isobutylthiophene-3-carboxylate

Crystal data

C11H17NO2S	F(000) = 488
Mr = 227.32	Dx = 1.204 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3288 reflections
a = 13.4321 (7) Å	θ = 2.5–27.0°
b = 9.4977 (7) Å	µ = 0.24 mm^−1
c = 9.8629 (10) Å	T = 293 K
β = 94.435 (1)°	Block, colorless
V = 1254.48 (17) Å^3	0.30 × 0.20 × 0.20 mm
Z = 4

Data collection

Bruker SMART 4K CCD area-detector diffractometer	2458 independent reflections
Radiation source: fine-focus sealed tube	1979 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.044
φ and ω scans	θmax = 26.0°, θmin = 1.5°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −16→16
Tmin = 0.931, Tmax = 0.954	k = −11→11
12038 measured reflections	l = −11→12

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)] = 0.070	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.172	H atoms treated by a mixture of independent and constrained refinement
S = 1.16	w = 1/[σ^2(Fo^2) + (0.08P)^2 + 0.4453P] where P = (Fo^2 + 2Fc^2)/3
2458 reflections	(Δ/σ)max = 0.001
145 parameters	Δρmax = 0.39 e Å^−3
0 restraints	Δρmin = −0.23 e Å^−3

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

	x	y	z	Uiso*/Ueq
C1	0.1600 (2)	0.2199 (3)	0.5726 (3)	0.0552 (8)
H1	0.1868	0.1542	0.6351	0.066*
C2	0.1898 (2)	0.3551 (3)	0.5718 (3)	0.0440 (6)
C3	0.13509 (18)	0.4346 (2)	0.4638 (3)	0.0389 (6)
C4	0.0652 (2)	0.3515 (3)	0.3900 (3)	0.0423 (6)
C5	0.2705 (2)	0.4095 (3)	0.6717 (3)	0.0540 (7)
H5A	0.2773	0.3455	0.7485	0.065*
H5B	0.2498	0.5000	0.7053	0.065*
C6	0.3726 (2)	0.4269 (3)	0.6161 (4)	0.0634 (9)
H6	0.3654	0.4930	0.5398	0.076*
C7	0.4119 (3)	0.2894 (5)	0.5640 (5)	0.1067 (15)
H7A	0.4772	0.3041	0.5334	0.160*
H7B	0.3678	0.2559	0.4898	0.160*
H7C	0.4157	0.2210	0.6359	0.160*
C8	0.4457 (3)	0.4899 (5)	0.7246 (5)	0.1052 (15)
H8A	0.4205	0.5786	0.7538	0.158*
H8B	0.5091	0.5041	0.6878	0.158*
H8C	0.4538	0.4269	0.8008	0.158*
C9	0.1436 (2)	0.5818 (3)	0.4294 (3)	0.0456 (7)
C10	0.2205 (3)	0.8022 (3)	0.4833 (4)	0.0785 (11)
H10A	0.1593	0.8524	0.4976	0.094*
H10B	0.2351	0.8148	0.3893	0.094*
C11	0.3024 (3)	0.8574 (4)	0.5739 (5)	0.0965 (14)
H11A	0.2876	0.8437	0.6667	0.145*
H11B	0.3104	0.9561	0.5569	0.145*
H11C	0.3630	0.8088	0.5577	0.145*
N1	−0.0020 (2)	0.3892 (3)	0.2887 (3)	0.0533 (7)
H1B	−0.039 (2)	0.330 (3)	0.245 (3)	0.064*
H1A	0.003 (2)	0.476 (4)	0.264 (3)	0.064*
O1	0.09739 (17)	0.6374 (2)	0.3336 (2)	0.0669 (6)
O2	0.20850 (15)	0.65355 (18)	0.5122 (2)	0.0583 (6)
S1	0.06791 (6)	0.17970 (7)	0.44771 (8)	0.0563 (3)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.071 (2)	0.0348 (14)	0.0594 (18)	0.0013 (13)	0.0021 (15)	0.0092 (13)
C2	0.0506 (15)	0.0360 (13)	0.0454 (15)	0.0012 (11)	0.0045 (12)	0.0013 (11)
C3	0.0460 (14)	0.0267 (12)	0.0439 (14)	0.0027 (10)	0.0022 (11)	−0.0006 (10)
C4	0.0532 (16)	0.0288 (12)	0.0448 (15)	0.0028 (10)	0.0036 (12)	−0.0028 (10)
C5	0.0629 (19)	0.0486 (16)	0.0484 (17)	0.0011 (13)	−0.0096 (14)	0.0034 (13)
C6	0.0577 (19)	0.0528 (18)	0.077 (2)	0.0024 (14)	−0.0096 (16)	0.0093 (16)
C7	0.076 (3)	0.088 (3)	0.157 (5)	0.021 (2)	0.011 (3)	−0.009 (3)
C8	0.077 (3)	0.115 (4)	0.118 (4)	−0.022 (2)	−0.028 (3)	0.004 (3)
C9	0.0459 (15)	0.0340 (13)	0.0560 (17)	0.0041 (11)	−0.0028 (13)	0.0018 (12)
C10	0.082 (2)	0.0294 (15)	0.122 (3)	−0.0067 (14)	−0.008 (2)	0.0089 (17)
C11	0.089 (3)	0.0433 (18)	0.154 (4)	−0.0178 (18)	−0.017 (3)	−0.006 (2)
N1	0.0638 (16)	0.0347 (12)	0.0587 (16)	−0.0010 (11)	−0.0130 (13)	−0.0068 (11)
O1	0.0819 (15)	0.0334 (10)	0.0808 (16)	0.0012 (10)	−0.0236 (12)	0.0112 (10)
O2	0.0646 (13)	0.0259 (9)	0.0815 (15)	−0.0064 (8)	−0.0132 (11)	0.0024 (9)
S1	0.0734 (6)	0.0293 (4)	0.0650 (5)	−0.0083 (3)	−0.0026 (4)	0.0018 (3)

Geometric parameters (Å, º)

C1—C2	1.345 (4)	C7—H7B	0.9600
C1—S1	1.720 (3)	C7—H7C	0.9600
C1—H1	0.9300	C8—H8A	0.9600
C2—C3	1.457 (3)	C8—H8B	0.9600
C2—C5	1.500 (4)	C8—H8C	0.9600
C3—C4	1.389 (4)	C9—O1	1.211 (3)
C3—C9	1.446 (3)	C9—O2	1.334 (3)
C4—N1	1.341 (4)	C10—O2	1.452 (3)
C4—S1	1.728 (3)	C10—C11	1.460 (5)
C5—C6	1.524 (4)	C10—H10A	0.9700
C5—H5A	0.9700	C10—H10B	0.9700
C5—H5B	0.9700	C11—H11A	0.9600
C6—C7	1.513 (5)	C11—H11B	0.9600
C6—C8	1.519 (5)	C11—H11C	0.9600
C6—H6	0.9800	N1—H1B	0.85 (3)
C7—H7A	0.9600	N1—H1A	0.86 (3)
C2—C1—S1	113.9 (2)	H7A—C7—H7C	109.5
C2—C1—H1	123.0	H7B—C7—H7C	109.5
S1—C1—H1	123.0	C6—C8—H8A	109.5
C1—C2—C3	111.4 (2)	C6—C8—H8B	109.5
C1—C2—C5	121.6 (3)	H8A—C8—H8B	109.5
C3—C2—C5	126.9 (2)	C6—C8—H8C	109.5
C4—C3—C9	119.2 (2)	H8A—C8—H8C	109.5
C4—C3—C2	111.8 (2)	H8B—C8—H8C	109.5
C9—C3—C2	128.9 (2)	O1—C9—O2	121.7 (2)
N1—C4—C3	128.8 (2)	O1—C9—C3	124.1 (3)
N1—C4—S1	119.6 (2)	O2—C9—C3	114.2 (2)
C3—C4—S1	111.54 (19)	O2—C10—C11	108.6 (3)
C2—C5—C6	115.2 (2)	O2—C10—H10A	110.0
C2—C5—H5A	108.5	C11—C10—H10A	110.0
C6—C5—H5A	108.5	O2—C10—H10B	110.0
C2—C5—H5B	108.5	C11—C10—H10B	110.0
C6—C5—H5B	108.5	H10A—C10—H10B	108.3
H5A—C5—H5B	107.5	C10—C11—H11A	109.5
C7—C6—C8	110.8 (3)	C10—C11—H11B	109.5
C7—C6—C5	112.1 (3)	H11A—C11—H11B	109.5
C8—C6—C5	109.9 (3)	C10—C11—H11C	109.5
C7—C6—H6	108.0	H11A—C11—H11C	109.5
C8—C6—H6	108.0	H11B—C11—H11C	109.5
C5—C6—H6	108.0	C4—N1—H1B	122 (2)
C6—C7—H7A	109.5	C4—N1—H1A	114 (2)
C6—C7—H7B	109.5	H1B—N1—H1A	123 (3)
H7A—C7—H7B	109.5	C9—O2—C10	117.0 (2)
C6—C7—H7C	109.5	C1—S1—C4	91.27 (13)
S1—C1—C2—C3	0.3 (3)	C2—C5—C6—C7	−59.4 (4)
S1—C1—C2—C5	−179.1 (2)	C2—C5—C6—C8	176.9 (3)
C1—C2—C3—C4	0.7 (3)	C4—C3—C9—O1	−4.7 (4)
C5—C2—C3—C4	−179.9 (2)	C2—C3—C9—O1	176.8 (3)
C1—C2—C3—C9	179.3 (3)	C4—C3—C9—O2	176.0 (2)
C5—C2—C3—C9	−1.4 (4)	C2—C3—C9—O2	−2.5 (4)
C9—C3—C4—N1	−2.6 (4)	O1—C9—O2—C10	0.8 (4)
C2—C3—C4—N1	176.1 (3)	C3—C9—O2—C10	−179.9 (3)
C9—C3—C4—S1	179.87 (19)	C11—C10—O2—C9	−173.3 (3)
C2—C3—C4—S1	−1.4 (3)	C2—C1—S1—C4	−1.0 (2)
C1—C2—C5—C6	101.9 (3)	N1—C4—S1—C1	−176.5 (2)
C3—C2—C5—C6	−77.4 (4)	C3—C4—S1—C1	1.4 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1B···O1^i	0.85 (3)	2.11 (3)	2.929 (3)	162 (3)
N1—H1A···O1	0.86 (3)	2.07 (3)	2.728 (3)	132 (3)
C6—H6···O2	0.98	2.60	3.193 (4)	119
C5—H5B···O2	0.97	2.43	2.888 (3)	109

Symmetry code: (i) −x, y−1/2, −z+1/2.