(2S,NS)-N-Allyl-N-benzyl-1-hydr­oxy-3-(4-hydroxy­phen­yl)-N-methyl­propan-2-aminium bromide

Hua-Fang Wu; Ying-Gang Luo; Kai-Bei Yu; Guo-Lin Zhang; Xin-Fu Pan

doi:10.1107/S1600536808023210

. 2008 Jul 31;64(Pt 8):o1621. doi: 10.1107/S1600536808023210

(2S,NS)-N-Allyl-N-benzyl-1-hydroxy-3-(4-hydroxyphenyl)-N-methylpropan-2-aminium bromide

Hua-Fang Wu ^a, Ying-Gang Luo ^b, Kai-Bei Yu ^c, Guo-Lin Zhang ^b,^*, Xin-Fu Pan ^a,^*

PMCID: PMC2962230 PMID: 21203311

Abstract

The title compound, C₂₀H₂₆NO₂ ⁺·Br⁻, is an N-chiral quaternary ammonium salt synthesized from (2S*)-N-benzyl-N-methyltyrosine methyl ester. The dihedral angle between the phenyl ring and the benzene ring is 11.61 (19)°. In the crystal structure, the allyl group is disordered over two positions with site occupancy factors of ca 0.8 and 0.2. The bromide anion links to the quaternary ammonium cations via O—H⋯Br hydrogen bonding. An intramolecular O—H⋯Br hydrogen bond is also observed.

Related literature

For general background, see: Maruoka & Ooi (2003 ▶); Ooi & Maruoka (2007 ▶). For a related structure, see: Tayama & Tanaka (2007 ▶). For synthesis, see: White & Konopelski (2005 ▶).

Experimental

Crystal data

C₂₀H₂₆NO₂ ⁺·Br⁻
M _r = 392.33
Orthorhombic,
a = 10.3716 (10) Å
b = 12.1566 (10) Å
c = 15.6790 (16) Å
V = 1976.9 (3) Å³
Z = 4
Mo Kα radiation
μ = 2.09 mm⁻¹
T = 293 (2) K
0.45 × 0.43 × 0.40 mm

Data collection

Rigaku R-AXIS RAPID IP diffractometer
Absorption correction: multi-scan (ABSCOR; Higashi, 1995 ▶) T _min = 0.406, T _max = 0.433
18872 measured reflections
4524 independent reflections
2606 reflections with I > 2σ(I)
R _int = 0.057

Refinement

R[F ² > 2σ(F ²)] = 0.054
wR(F ²) = 0.211
S = 1.00
4524 reflections
225 parameters
2 restraints
H-atom parameters constrained
Δρ_max = 0.89 e Å⁻³
Δρ_min = −0.69 e Å⁻³
Absolute structure: Flack (1983 ▶), with 1949 Friedel pairs
Flack parameter: 0.009 (19)

Data collection: RAPID-AUTO (Rigaku, 2004 ▶); cell refinement: RAPID-AUTO; data reduction: RAPID-AUTO; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808023210/xu2435sup1.cif

e-64-o1621-sup1.cif^{(21.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808023210/xu2435Isup2.hkl

e-64-o1621-Isup2.hkl^{(221.7KB, hkl)}

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
O1—H1O⋯Br1	0.82	2.43	3.231 (4)	167
O2—H2O⋯Br1ⁱ	0.82	2.38	3.192 (5)	171

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Symmetry code: (i) Inline graphic .

Acknowledgments

This work was supported financially by the National Natural Science Foundation of China (grant No. 20672108).

supplementary crystallographic information

Comment

As an important class of asymmetric catalysts of phase-transfer catalysts, chiral quaternary ammonium salts show great application in asymmetric organic synthesis (Maruoka & Ooi, 2003; Ooi & Maruoka, 2007). The title compound is a N-chiral quaternary ammonium salt (N-CQAS), we present here its structure.

The molecular structure is shown in Fig. 1. The quaternary ammonium cation displays an extended structure, the C14—N1—C8—C7 torsion angle is 179.3 (5)°. The terminal C1-benzene and C15-phenyl rings are nearly parallel to each other [dihedral angle 11.61 (19)°], and approximately perpendicular to the central C7/C6/N1/C14 mean plane with dihedral angles of 85.1 (3) and 88.8 (4)°, respectively. Bond lengths and angles agree with those found in a reported N-chiral quaternary ammonium salt (Tayama & Tanaka, 2007).

In the crystal structure the Br^- anion links with the quaternary ammonium cations via O—H···Br hydrogen bonding (Table 1), to form the one dimensional supra-molecular structure along the b axis (Fig. 2).

Experimental

(2S*)-N-Benzyl-N-methyltyrosine methyl ester (White & Konopelski, 2005) (1 mmol) was reduced by lithium aluminium hydride (1 mmol) to afford (2S*)-N-Benzyl-N-methyl-2-amino-3-(4-hydroxyphenyl)propan-1-ol, which was then dissolved in absolute acetonitrile (5 ml), and allyl bromide (2 mmol) was added. The mixture was heated to reflux for 42 h. After being cooled to room temperature, the excess allyl bromide and acetonitrile were removed under reduced pressure. The residue was purified by flash chromatography eluted with ethyl acetate/methanol (8:1) to afford the diastereomeric mixture of the N-CQAS with yields (90%). The mixture was recrystallized from ethanol to afford the single crystals of the title compound. Yield (41%).