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Acta Cryst. (2007). E63, o3355    [ doi:10.1107/S1600536807030565 ]

(3R,4S)-2-Isopropyl-3-methyl-4-phenyl-3,4-dihydroisoquinolinium iodide

K. Ben Ali, A. Chiaroni and L. Bohe

Abstract top

The title compound, C19H22N+·I-, is a new dihydroisoquinolinium salt, used as a catalyst in asymmetric epoxidation. It was characterized by NMR spectroscopy and X-ray crystallographic techniques. The absolute configurations of the two stereogenic centres were established by the refinement of the Flack parameter to be 3R and 4S.

Comment top

Catalytic asymmetric epoxidation of alkenes is an exceptionally valuable synthetic transformation (Xia et al.,2005). The development of efficient methods for asymmetric epoxidation of simple, 'unfunctionalized' alkenes is a particular challenge, and some of the most spectacular progress in recent years has come from the use of oxaziridinum salts generated in situ by oxidation of chiral iminium salts (Bohé et al., 1999). As part of our interest in oxaziridinium chemistry and particularly in the rational design of dihydroisoquinolinium-derived catalysts able to improve the catalytic oxygen transfer process, we examined the influence of the exocyclic substituent on the nitrogen atom on the ee induced in an epoxidation reaction. Thus we prepared the iminium salt (2) and evaluated its behavior in the catalytic system (Fig. 1). We report herein the synthesis and the crystal structure determination of the title compound. Synthesis of the title compound involved heating a mixture of the corresponding diydroisoquinoline (2) and isopropyl iodide for 24 h. Imine (2) was prepared as described by Bohé et al.(1999), in four steps from (1S, 2R)-norephedrine (1).

In the title compound, the tetrahydroisoquinoline unit is substituted by a methyl group in position 3, a phenyl substituent in position 4, and a cyclohexane ring at the nitrogen (Fig. 2). The heterocyclic ring adopts a half-chair conformation as indicated by puckering analysis [QT= 0.458 (5)Å and θ= 62.1 (6)°] (Cremer & Pople, 1975). The substituents in positions 3 and 4 of the heterocyclic ring are in axial conformation with respect to this ring and the X-ray analyses allowed to define the absolute configuration of C3(R) and C4(S).

Related literature top

For general background see: Bohé et al. (1999); Xia et al. (2005). For related literature, see: Cremer & Pople (1975).

Experimental top

Compound (3) was prepared by reaction of imine (2) (3.470 g, 16 mmol), and isopropyl iodide (8 ml, 80 mmol) in acetonitrile (80 ml)·The mixture was heated at reflux for 24 h. On completion of the reaction, as monitored by TLC, the solvent was removed in vacuum and the product purified by flash chromatography on silica, with dichloromethane/methanol (90/10) as eluent (yield 95%). m.p. 457 K. [α] D22 – 62 (c 1; CHCl3). Spectroscopic analysis, 1H NMR (400 MHz; CDCl3, p.p.m): 1.23 (d, J = 6.2, 3H, Me20); 1.24 (d, J = 6.2,3H, Me19); 1.58 (d, J = 6.7, 3H, Me11); 4.37 (q, J = 6.7, 1H, H3); 4.47 (s,1H, H4); 4.54 (dq, J = 6.2, J = 6.2, 1H, H18); 6.87 (d, J = 6.5, 2H, aromatic H); 7.30 (m, 3H, aromatic H); 7.40 (d, J = 7.5, 1H, aromatic H); 7.63 (t, J = 7.3, 1H, aromatic H); 7.80 (t, J = 7.6, 1H, aromatic H); 8.70 (d, J = 7.2, 1H, aromatic H); 10.54 (s, 1H, H1). 13 C NMR (62.5 MHz; CDCl3): 18.92, 20.33,21.12, 48.12, 61.61, 62.67, 125.10, 127.69, 128.51, 129.48, 129.74, 130.16, 135.75, 136.22, 138.78, 163.74. m/z (ESI+): 264 (M—I)+. Anal.: Calcd for C19H22NI: C 58.32%; H 5.67%; N 3.58%. Found: C 58.44%; H 5.79%; N 3.44% Recrystallization from acetone afford yellow crystals suitable for diffraction.

Refinement top

All H atoms were positioned geometrically and treated as riding, with C—H = 0.93 (aromatic), 0.96 (methyl), or 0.98 Å (methine), with Uiso(H) = xUeq(C) where x = 1.5 for methyl H and 1.2 for all other H atoms. Friedel opposites were not merged. The absolute configuration C3(R),C4(S) was determined from the anomalous scattering contribution of the iodide anion, using 1602 Friedel pairs.

Computing details top

Data collection: COLLECT (Hooft, 1998); cell refinement: DENZO (Otwinowski & Minor, 1997); data reduction: DENZO; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

Figures top
[Figure 1] Fig. 1. Chemical pathway of the formation of (3).
[Figure 2] Fig. 2. Molecular view of the title compound showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level·H atoms are represented as small spheres of arbitrary radii.
(3R,4S)-2-Isopropyl-3-methyl-4-phenyl-3,4-dihydroisoquinolinium iodide top
Crystal data top
C19H22N+·I−Dx = 1.444 Mg m−3
Mr = 391.28Melting point: 457 K
Hexagonal, P61Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 61Cell parameters from 3639 reflections
a = 9.773 (4) Åθ = 1.0–27.5°
c = 32.630 (12) ŵ = 1.77 mm−1
V = 2699.0 (19) Å3T = 293 K
Z = 6Prism, yellow
F(000) = 11760.40 × 0.35 × 0.35 mm
Data collection top
Nonius KappaCCD
diffractometer		3694 independent reflections
Radiation source: fine-focus sealed tube2992 reflections with I > 2σ(I)
graphiteRint = 0.014
φ and ω scansθmax = 27.5°, θmin = 2.4°
Absorption correction: multi-scan
(SCALEPACK; Otwinowski & Minor, 1997)		h = −12→12
Tmin = 0.491, Tmax = 0.540k = −10→10
6545 measured reflectionsl = −42→34
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.038H-atom parameters constrained
wR(F2) = 0.086 w = 1/[σ2(Fo2) + (0.0277P)2 + 2.172P]
where P = (Fo2 + 2Fc2)/3
S = 1.02(Δ/σ)max = 0.002
3694 reflectionsΔρmax = 0.55 e Å−3
193 parametersΔρmin = −1.01 e Å−3
1 restraintAbsolute structure: Flack (1983), 1602 Friedel pairs
Primary atom site location: structure-invariant direct methodsFlack parameter: 0.01 (3)
Crystal data top
C19H22N+·I−Z = 6
Mr = 391.28Mo Kα radiation
Hexagonal, P61µ = 1.77 mm−1
a = 9.773 (4) ÅT = 293 K
c = 32.630 (12) Å0.40 × 0.35 × 0.35 mm
V = 2699.0 (19) Å3
Data collection top
Nonius KappaCCD
diffractometer		3694 independent reflections
Absorption correction: multi-scan
(SCALEPACK; Otwinowski & Minor, 1997)		2992 reflections with I > 2σ(I)
Tmin = 0.491, Tmax = 0.540Rint = 0.014
6545 measured reflectionsθmax = 27.5°
Refinement top
R[F2 > 2σ(F2)] = 0.038H-atom parameters constrained
wR(F2) = 0.086Δρmax = 0.55 e Å−3
S = 1.02Δρmin = −1.01 e Å−3
3694 reflectionsAbsolute structure: Flack (1983), 1602 Friedel pairs
193 parametersFlack parameter: 0.01 (3)
1 restraint
Special details top

Refinement. Refinement of F2 against ALL reflections except one truncated by the beamstop. 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
I10.64454 (5)0.68377 (4)0.139072 (16)0.1060 (2)
C10.7788 (5)0.4692 (5)0.20412 (13)0.0535 (10)
H10.81420.57300.21210.060*
N20.8719 (4)0.4388 (4)0.18374 (10)0.0528 (8)
C30.8106 (5)0.2778 (5)0.16614 (15)0.0599 (11)
H30.90060.26220.16100.067*
C40.7003 (5)0.1521 (5)0.19702 (15)0.0606 (11)
H40.64460.05160.18220.068*
C50.4251 (6)0.0766 (6)0.22239 (18)0.0740 (14)
H50.3941−0.02980.21980.083*
C60.3199 (6)0.1186 (8)0.23685 (19)0.0853 (17)
H60.21830.04060.24400.096*
C70.3627 (6)0.2737 (9)0.24090 (19)0.0837 (17)
H70.28980.30090.25050.094*
C80.5150 (6)0.3917 (6)0.23068 (16)0.0692 (13)
H80.54540.49760.23410.078*
C90.6205 (5)0.3492 (5)0.21536 (13)0.0508 (9)
C100.5777 (5)0.1908 (5)0.21141 (14)0.0543 (10)
C110.7318 (7)0.2690 (7)0.12538 (15)0.0827 (16)
H11A0.69990.16880.11270.099*
H11B0.80490.35250.10780.099*
H11C0.64070.28000.12980.099*
C120.7885 (5)0.1284 (5)0.23205 (16)0.0582 (11)
C130.8437 (6)0.2279 (6)0.26558 (16)0.0666 (12)
H130.82170.30980.26780.075*
C140.9315 (6)0.2078 (7)0.29619 (18)0.0766 (14)
H140.97220.27890.31790.086*
C150.9572 (7)0.0836 (9)0.2941 (2)0.094 (2)
H151.01370.06790.31470.105*
C160.8997 (7)−0.0179 (8)0.2617 (3)0.096 (2)
H160.9167−0.10330.26050.108*
C170.8179 (6)0.0037 (6)0.2311 (2)0.0740 (14)
H170.7812−0.06630.20910.083*
C181.0400 (5)0.5578 (6)0.17395 (16)0.0718 (13)
H181.06010.53930.14560.080*
C191.0690 (7)0.7252 (6)0.1764 (2)0.097 (2)
H19A1.17220.79720.16590.116*
H19B1.06220.75100.20440.116*
H19C0.99080.73330.16040.116*
C201.1482 (6)0.5291 (9)0.2014 (2)0.097 (2)
H20A1.13920.55700.22910.116*
H20B1.25540.59270.19230.116*
H20C1.11850.41960.20030.116*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
I10.0964 (3)0.0813 (3)0.0739 (2)−0.00536 (18)−0.0301 (2)0.0212 (2)
C10.064 (3)0.052 (2)0.047 (2)0.031 (2)−0.0024 (19)−0.0007 (18)
N20.0505 (19)0.0547 (19)0.0459 (19)0.0208 (16)−0.0008 (15)−0.0027 (15)
C30.062 (3)0.071 (3)0.050 (2)0.036 (2)−0.004 (2)−0.018 (2)
C40.062 (3)0.050 (2)0.067 (3)0.026 (2)−0.010 (2)−0.020 (2)
C50.057 (3)0.063 (3)0.082 (4)0.016 (2)−0.006 (3)0.010 (3)
C60.052 (3)0.111 (5)0.081 (4)0.031 (3)0.007 (3)0.027 (3)
C70.066 (3)0.128 (5)0.075 (4)0.061 (4)0.010 (3)0.020 (3)
C80.079 (3)0.082 (3)0.065 (3)0.053 (3)0.012 (3)0.013 (3)
C90.052 (2)0.057 (2)0.046 (2)0.030 (2)0.0008 (17)0.0041 (18)
C100.049 (2)0.058 (2)0.054 (3)0.025 (2)−0.0067 (19)0.0007 (19)
C110.081 (3)0.103 (4)0.051 (3)0.036 (3)−0.013 (2)−0.019 (3)
C120.057 (2)0.048 (2)0.076 (3)0.030 (2)0.004 (2)0.002 (2)
C130.078 (3)0.061 (3)0.068 (3)0.039 (2)−0.011 (3)−0.002 (2)
C140.070 (3)0.096 (4)0.070 (4)0.045 (3)0.000 (2)0.018 (3)
C150.061 (3)0.119 (5)0.116 (5)0.057 (3)0.027 (3)0.063 (4)
C160.083 (4)0.083 (4)0.151 (7)0.062 (3)0.032 (4)0.040 (4)
C170.070 (3)0.059 (3)0.101 (4)0.038 (3)0.015 (3)0.002 (3)
C180.052 (3)0.094 (4)0.050 (3)0.023 (2)0.003 (2)−0.005 (2)
C190.082 (4)0.073 (3)0.081 (4)−0.002 (3)0.005 (3)0.004 (3)
C200.057 (3)0.141 (6)0.083 (4)0.042 (3)−0.009 (3)−0.019 (4)
Geometric parameters (Å, °) top
C1—N21.276 (5)C11—H11B0.9600
C1—C91.445 (6)C11—H11C0.9600
C1—H10.9300C12—C131.381 (7)
N2—C31.491 (5)C12—C171.385 (6)
N2—C181.497 (5)C13—C141.393 (7)
C3—C111.517 (7)C13—H130.9300
C3—C41.537 (7)C14—C151.359 (8)
C3—H30.9800C14—H140.9300
C4—C101.501 (6)C15—C161.364 (9)
C4—C121.518 (7)C15—H150.9300
C4—H40.9800C16—C171.361 (9)
C5—C61.367 (8)C16—H160.9300
C5—C101.391 (6)C17—H170.9300
C5—H50.9300C18—C201.516 (8)
C6—C71.362 (8)C18—C191.516 (8)
C6—H60.9300C18—H180.9800
C7—C81.393 (8)C19—H19A0.9600
C7—H70.9300C19—H19B0.9600
C8—C91.383 (6)C19—H19C0.9600
C8—H80.9300C20—H20A0.9600
C9—C101.393 (6)C20—H20B0.9600
C11—H11A0.9600C20—H20C0.9600
N2—C1—C9122.8 (4)C3—C11—H11C109.5
N2—C1—H1118.6H11A—C11—H11C109.5
C9—C1—H1118.6H11B—C11—H11C109.5
C1—N2—C3119.3 (4)C13—C12—C17117.2 (5)
C1—N2—C18124.3 (4)C13—C12—C4122.8 (4)
C3—N2—C18116.3 (4)C17—C12—C4120.0 (5)
N2—C3—C11108.8 (4)C12—C13—C14121.3 (5)
N2—C3—C4110.0 (3)C12—C13—H13119.3
C11—C3—C4113.3 (4)C14—C13—H13119.3
N2—C3—H3108.2C15—C14—C13119.5 (6)
C11—C3—H3108.2C15—C14—H14120.3
C4—C3—H3108.2C13—C14—H14120.3
C10—C4—C12112.9 (4)C14—C15—C16119.7 (6)
C10—C4—C3109.4 (4)C14—C15—H15120.2
C12—C4—C3113.0 (4)C16—C15—H15120.2
C10—C4—H4107.1C17—C16—C15121.1 (5)
C12—C4—H4107.1C17—C16—H16119.4
C3—C4—H4107.1C15—C16—H16119.4
C6—C5—C10120.9 (5)C16—C17—C12121.0 (6)
C6—C5—H5119.5C16—C17—H17119.5
C10—C5—H5119.5C12—C17—H17119.5
C7—C6—C5120.6 (5)N2—C18—C20109.0 (4)
C7—C6—H6119.7N2—C18—C19111.5 (4)
C5—C6—H6119.7C20—C18—C19113.4 (5)
C6—C7—C8120.2 (5)N2—C18—H18107.5
C6—C7—H7119.9C20—C18—H18107.5
C8—C7—H7119.9C19—C18—H18107.5
C9—C8—C7119.1 (5)C18—C19—H19A109.5
C9—C8—H8120.4C18—C19—H19B109.5
C7—C8—H8120.4H19A—C19—H19B109.5
C8—C9—C10120.8 (4)C18—C19—H19C109.5
C8—C9—C1120.2 (4)H19A—C19—H19C109.5
C10—C9—C1118.9 (4)H19B—C19—H19C109.5
C5—C10—C9118.3 (4)C18—C20—H20A109.5
C5—C10—C4123.3 (4)C18—C20—H20B109.5
C9—C10—C4118.4 (4)H20A—C20—H20B109.5
C3—C11—H11A109.5C18—C20—H20C109.5
C3—C11—H11B109.5H20A—C20—H20C109.5
H11A—C11—H11B109.5H20B—C20—H20C109.5
C9—C1—N2—C37.8 (6)C1—C9—C10—C42.1 (6)
C9—C1—N2—C18−175.7 (4)C12—C4—C10—C5−85.0 (6)
C1—N2—C3—C1183.8 (5)C3—C4—C10—C5148.2 (5)
C18—N2—C3—C11−92.9 (5)C12—C4—C10—C992.6 (5)
C1—N2—C3—C4−40.9 (5)C3—C4—C10—C9−34.1 (5)
C18—N2—C3—C4142.4 (4)C10—C4—C12—C13−44.2 (6)
N2—C3—C4—C1051.6 (5)C3—C4—C12—C1380.7 (5)
C11—C3—C4—C10−70.5 (5)C10—C4—C12—C17136.4 (4)
N2—C3—C4—C12−75.1 (5)C3—C4—C12—C17−98.8 (5)
C11—C3—C4—C12162.8 (4)C17—C12—C13—C142.9 (7)
C10—C5—C6—C7−0.1 (9)C4—C12—C13—C14−176.6 (5)
C5—C6—C7—C8−0.7 (9)C12—C13—C14—C15−3.2 (8)
C6—C7—C8—C91.8 (9)C13—C14—C15—C161.4 (8)
C7—C8—C9—C10−2.2 (7)C14—C15—C16—C170.6 (9)
C7—C8—C9—C1179.3 (5)C15—C16—C17—C12−0.9 (9)
N2—C1—C9—C8−168.1 (5)C13—C12—C17—C16−0.9 (7)
N2—C1—C9—C1013.4 (6)C4—C12—C17—C16178.6 (5)
C6—C5—C10—C9−0.3 (8)C1—N2—C18—C20104.5 (5)
C6—C5—C10—C4177.4 (5)C3—N2—C18—C20−79.0 (5)
C8—C9—C10—C51.5 (7)C1—N2—C18—C19−21.5 (6)
C1—C9—C10—C5179.9 (4)C3—N2—C18—C19155.0 (4)
C8—C9—C10—C4−176.3 (4)
references
References top

Bohé, L., Lusinchi, M. & Lusinchi, X. (1999). Tetrahedron, 55, 141–154.

Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354–1358.

Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565–?.

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Hooft, R. (1998). COLLECT. Nonius BV, Delft, The Netherlands.

Otwinowski, Z. & Minor, W. (1997). Methods Enzymol. 276, 307–326.

Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of Göttingen, Germany.

Xia, Q. H., Ge, H. Q., Ye, C. P., Liu, Z. M. & Su, K. X. (2005). Chem. Rev. 105, 1603–1662.