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Journal of Chemical Crystallography, Vol. 33, No. 10, October 2003 (C© 2003)

Formation and crystal structure of1-methyl-2-phenylindolizine-3-acetonitrile

Weiwei Liu, (1) Song Ou,(1) Xiang He,(1) Hongwen Hu,(1)∗

Qiangjin Wu, (2) and Zixiang Huang(2)

Received January 28, 2002

1-Methyl-2-phenylindolizine-3-acetonitrile was unexpectedly obtained in the reaction of 1-methyl-2-phenylindolizine-3-thioaldehyde with cyanide ions. Its structure was determinedby IR, 1H NMR, MS, elemental analyses, and X-ray crystallography. Colorless regularprism shaped crystals of C17H14N2 crystallize in the space groupC2/c with cell dimensionsa= 12.956(3)A, b= 10.516(2)A, c= 20.429(4)A, andα= 90◦, β = 104.98(3)◦, γ = 90◦,V = 2688.7(9)A3, Dcalc= 1.217 Mg/m3, andZ= 8.

KEY WORDS: Indolizine; X-ray crystal structure; cyanide ion.

Introduction

It is well known that thioaldehydes areunstable and polymerize readily. However,resonance stabilized thioaldehydes, for example,indolizine thioaldehydes are stable and are easilyprepared.1,2 As a part of our research project on in-dolizine chemistry,3,4 the reactions of indolizine-thioaldehydes were studied, and we found thatthe reaction of these thioaldehydes with sodiumcyanide takes an entirely different pathway fromthe benzoin condensation of aromatic aldehydes.For example, by treating 1-methyl-2-phenylindo-lizine3-thioaldehyde (1) with sodium cyanide, weobtained 1-methyl-2-phenylindolizine-3-acetoni-trile (2) as one of the reaction products (Scheme 1).In order to further confirm the structure of this un-

(1) Department of Chemistry, Nanjing University, Nanjing 210093,People’s Republic of China.

(2) Fujian Institute of Research on the Structure of Matter, ChineseAcademy of Sciences, Fujian, People’s Republic of China.

∗ To whom correspondence should be addressed. E-mail: xujh@nju.edu.cn

expected product, a single-crystal X-ray diffrac-tion measurement was undertaken.

Experimental

Preparation of 1-methyl-2-phenylindolizine-3-acetonitrile (2) and spectroscopic analysis

Melting points were determined on a Yanacomelting point apparatus and are uncorrected. IRSpectra were recorded on a Nicolet FT-IR 5DXspectrometer with KBr pellets.1H NMR spectrawere recorded on a Bruker ACF-300 spectrome-ter with TMS as internal reference.J values aregiven in Herz. Mass spectra were obtained on aZAB-HS mass spectrometer at 70 eV. Elementalanalyses were performed on a Perkin-Elmer 240Cinstrument. Compound1 was prepared accordingto reported procedures.2

A solution of 1-methyl-2-phenylindolizine-3-thioaldehyde (1) (620 mg, 2.47 mmol) andsodium cyanide (68 mg, 1.38 mmol) in anhydrousDMF(10 mL) and DMSO (3 mL) was stirred at

795

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Scheme 1.

50◦ for 1.5 h (monitored by TLC). It was thencooled to room temperature, the solvent wasremoved in vacuo and the residue was separatedby gradient elution chromatography on a aluminacolumn with petroleum ether (bp 60–90◦C)and ethyl acetate as eluents to give 1-methyl-2-phenylindolizine-3-acetonitrile (2) (162 mg atyield 26%) as colorless crystals, mp 113–114◦

(from petroleum ether bp 60–90◦C) (Found: C,82.92; H, 5.83; N, 11.36. C17H14N2 requires C,82.93; H, 5.69; N, 11.38%).νmax/cm−1 3074,3054, 3039, 3020, 2959, 2917, 2858, 2246, 1883,1745, 1603, 1418, 1367, 725, 706.δH /ppm 2.27(3H, s,---CH3), 4.19 (2H, s, CH2CN), 6.71–6.83(2H, m, ArH), 7.35–7.45 (3H, m, ArH), 7.49–7.58(3H, m, ArH), 8.11 (1H, d,J= 6.9, ArH). m/z(%) 246 (M+, 100), 231 (13), 218 (19), 206 (12),204 (20), 108 (10), 78 (14), 51 (7).

X-ray analysis

Colorless prismatic crystals of2 (C17H14N2)were obtained by slow evaporation of the solventfrom acetone solution. The intensity data were col-lected on a Enraf-Nonius CAD4 diffractometerusing graphite monochromated MoKα radiation(λ = 0.71073A). The crystal data and a summaryof intensity data collection parameters are listedin Table 1.

The intensities were corrected for Lorentzand polarization effects. The structure was solvedby direct methods and refinement was per-formed by full-matrix least-squares methods withanisotropic parameters for all non-H-atoms. Theatomic coordinates and equivalent isotropic dis-placement parameters are given in Table 2, and

Table 1. Crystal Data and Structure Refinement for2

Compound C17H14N2

CCDC deposit no. 210569Color/shape Colorless/prismaticFormula weight 246.30Temperature 293(2) KWavelength 0.71073ACrystal system MonoclinicSpace group C2/cUnit cell dimensions a= 12.956(3)A

b= 10.516(2)Ac= 20.429(4)Aα = 90◦β = 104.98(3)◦γ = 90◦

Diffractometer/scan Enraf-Nonius CAD4Volume 2688.7(9)A3

Z 8Density(calculated) 1.217 Mg/m3

Absorption coefficient 0.072 mm−1

F000 1040θ range for data collection 2.06–26.00◦Limiting indices 0< h ≤ 15,−12≤ k ≤ 0,

−25≤ l ≤ 24Reflections collected/unique 2661/2543 [Rint = 0.0474]Completeness toθ = 26.00 95.9%Refinement method Full-matrix least-squares onF2

Data/restraints/parameters 2543/0/173Goodness of fit onF2 1.047Final R indices [I > 2σ (I )] R1 = 0.0718,wR2 = 0.1938R indices (all data) R1 = 0.1216,wR2 = 0.2282Extinction coefficient 0.008Largest diff. peak and hole 0.220 and−0.227

the molecular structure with atomic numbering areshown in Fig 1. Selected bond lengths and anglesare listed in Table 3.

Result and discussion

X-ray analysis

The crystal structure is shown in Fig. 1. Thetitle compound is composed of indolizine (ringsA, B) and phenyl (ring C). The correspondingbond lengths and angles in the indolizine nucleusare very similar to those seen in other indolizinederivatives.5–7 It is also seen that, similar toother reported indolizine structure,5–7 ring A

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Formation of indolizine-3-acetonitrile 797

Table 2. Atomic Coordinates and Equivalent Isotropic DisplacementParameters for2a

Atom x y z Ueq

N(1) 8869(2) 1652(3) 5248(1) 47(1)N(2) 10337(3) 4236(3) 4279(2) 81(1)C(1) 9215(3) 2337(4) 5842(2) 60(1)C(2) 9474(3) 1728(4) 6439(2) 70(1)C(3) 9402(3) 392(4) 6469(2) 72(1)C(4) 9065(3) −294(4) 5896(2) 61(1)C(5) 8771(2) 313(3) 5258(1) 45(1)C(6) 8370(2) −88(3) 4599(1) 46(1)C(7) 8179(3) −1451(3) 4387(2) 61(1)C(8) 8221(2) 1002(3) 4183(1) 47(1)C(9) 8532(2) 2056(3) 4591(1) 47(1)C(10) 8503(2) 3439(3) 4419(2) 52(1)C(11) 9535(3) 3911(3) 4341(2) 55(1)C(12) 7800(2) 1037(3) 3438(1) 48(1)C(13) 6890(3) 363(4) 3118(2) 59(1)C(14) 6483(3) 399(4) 2422(2) 68(1)C(15) 6987(4) 1113(4) 2029(2) 75(1)C(16) 7885(3) 1794(4) 2333(2) 71(1)C(17) 8306(3) 1750(3) 3032(2) 59(1)

aUeq is defined as one third of the trace of the orthogonalizedUi j

tensor.

Table 3. Bond Lengths (A) and Angles (◦) for 2

Bond lengthsN(1)---C(9) 1.367(4) N(1)---C(1) 1.383(4)N(1)---C(5) 1.414(4) N(2)---C(11) 1.131(4)C(1)---C(2) 1.340(5) C(2)---C(3) 1.410(6)C(3)---C(4) 1.348(5) C(4)---C(5) 1.412(4)C(5)---C(6) 1.379(4) C(6)---C(8) 1.411(4)C(6)---C(7) 1.499(4) C(8)---C(9) 1.383(4)C(8)---C(12) 1.477(4) C(9)---C(10) 1.495(4)C(10)---C(11) 1.473(5) C(12)---C(13) 1.387(4)C(12)---C(17) 1.399(4) C(13)---C(14) 1.384(5)C(14)---C(15) 1.380(5) C(15)---C(16) 1.371(6)C(16)---C(17) 1.391(5)

Bond anglesC(9)---N(1)---C(1) 130.4(3) C(9)---N(1)---C(5) 108.5(2)C(1)---N(1)---C(5) 121.1(3) C(2)---C(1)---N(1) 119.8(4)C(1)---C(2)---C(3) 120.8(3) C(4)---C(3)---C(2) 120.3(3)C(3)---C(4)---C(5) 120.6(4) C(6)---C(5)---C(4) 135.0(3)C(6)---C(5)---N(1) 107.6(2) C(4)---C(5)---N(1) 117.4(3)C(5)---C(6)---C(8) 107.4(3) C(5)---C(6)---C(7) 124.6(3)C(8)---C(6)---C(7) 128.0(3) C(9)---C(8)---C(6) 108.3(3)C(9)---C(8)---C(12) 125.0(3) C(6)---C(8)---C(12) 126.7(3)N(1)---C(9)---C(8) 108.2(3) N(1)---C(9)---C(10) 121.1(3)C(8)---C(9)---C(10) 130.7(3) C(11)---C(10)---C(9) 112.7(3)N(2)---C(11)---C(10) 177.8(4) C(13)---C(12)---C(17) 117.8(3)C(13)---C(12)---C(8) 121.0(3) C(17)---C(12)---C(8) 121.3(3)C(14)---C(13)---C(12) 121.4(3) C(15)---C(14)---C(13) 120.1(3)C(16)---C(15)---C(14) 119.6(3) C(15)---C(16)---C(17) 120.6(4)C(16)---C(17)---C(12) 120.5(3)

Fig. 1. ORTEP drawing of the molecule 2 (50% probabilityellipsoids).

and ring B are coplanar (torsion angle: C(9)---N(1)---C(5)---C(4) = −179.0(3)◦), the dihedralangle between ring B and the indolizine skeletonplane (rings A and B as a whole) is 1.12(0.03)◦.Indolizine and the phenyl are bonded by C8 andC12, the dihedral angle between ring B and ringC is 46.69(0.03)◦, which indicates that ring C istwisted out of the indolizine plane because of thesteric interaction between the methyl at C(1), thecyanomethyl at C(3) and the ring C. The phenyl,however, can still slightly conjugate with rings Aand B (bond length: C(8)---C(12)= 1.477(4)A,C(6)---C(7) = 1.499(4)A, C(9)---C(10) = 1.495(4)A). C(7), C(10), and C(12) are coplanar withindolizine (torsion angle: C(7)---C(6)---C(5)---N(1)= 178.0(3)◦, C(5)---N(1)---C(9)---C(10)=177.8 (2)◦, and C(5)---C(6)---C(8)---C(12)=− 179.6(3)◦).

The cyanomethyl group (C(10)---C(11)---N(2) is not coplanar with but almost per-pendicular to the indolizine ring (torsionangle: C(11)---C(10)---C(9)---N(1) = 85.9(3)◦,N(2)---C(11)---C(10)---C(9) = 16.6(3)◦), andthe cyano group is bent toward the indolizinenucleus (bond angle: N(2)---C(11)---C(10)=177.8(4)◦, C(11)---C(10)---C(9)= 112.7(3)◦).

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This minimizes the steric interaction between thecyano-methyl and the phenyl ring.

Spectroscopic analysis

The1H NMR and IR data of compound2 arein good agreement with its structure . In the IRspectrum, the cyano absorption is at 2246 cm−1,methyl and methylene C---H stretching absorp-tions are at 2959, 2917, and 2858 cm−1, phenyland indolizine absorption are at 3074, 3054, 3039,3020, 1603, 1418, 725, and 706 cm−1. In the1HNMR spectrum, the two methylene protons andthree methyl protons resonate as two single peaksat δ 4.19 and 2.27, respectively. The molecularweight (246) is consistent with the structure. The

peaks at 231 and 206 in the MS are M+---CH3 andM+---CH2CN, respectively.

Acknowledgment

We thank NSF of China for financial support.

References

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Soc., Perkin 11999, 1571.4. Hu, J.; Jiang, X.; He, T.; Zhou, J.; Hu, Y.; Hu, H.J. Chem. Soc.,

Perkin 12001, 1820.5. Usman, A.; Li, Y.; Zhang, Y.; Fun, H.-K.; Xu, J.-H.Acta Crys-

tallogr. 2002, E58, o1427.6. Oeser, E.Chem. Ber.1972, 105, 2351.7. Tafeenkov, V.A.; Au, O.Zh. Strukt. Khim. 1996, 37, 1181.