(4S,5S)-(+)-Hydroxymethyl-2,5-diphenyloxazoline

Full text of DOI:10.1107/S0108270100006818

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
ISSN 0108-2701
(4S,5S)-(+)-4-Hydroxymethyl-2,5-di-
phenyloxazoline
Andrzej Gzellaa* and Maria D. Rozwadowskab
aDepartment of Organic Chemistry, K. Marcinkowski University of Medical Sciences
Poznan, ul. Grunwaldzka 6, 60-780 Poznan, Poland, and bFaculty of Chemistry,
Â
Â
Â
A. Mickiewicz University, ul. Grunwaldzka 6, 60-780 Poznan, Poland
Figure 1
Correspondence e-mail: akgzella@eucalyptus.usoms.poznan.pl
The molecular structure of (II) with displacement ellipsoids drawn at the
50% probability level. H atoms, treated as isotropic, are on an arbitrary
scale.
Received 31 January 2000
Accepted 4 May 2000
& Williams (400±402 K) and Hoarau et al. (408 K). Moreover,
we reported poor solubility of the compound in chloroform at
room temperature. Since oxazolines are intermediates in the
O ! N acyl group migration in acylated 1,2-aminoalcohols,
involving in some cases inversion of con®guration, we decided
to con®rm unambiguously the structure of oxazoline (II) of
m.p. 459±460 K and [ꢁ]D20 = +51.0 (c = 0.54, CHCl3) by X-ray
analysis.
For the (+)-enantiomer shown in Fig. 1, the tetrahedral C4
and C5 atoms are chiral centres. The absolute con®guration of
those atoms was established as 4S and 5S by the structure
re®nement using Bijvoet-pair re¯ections. The hydroxymethyl
group at the asymmetric C4 atom exhibits a ꢀ-orientation,
whereas the phenyl group at the asymmetric C5 atom is ꢁ-
The absolute con®guration of the title compound, alter-
natively called (+)-(4,5-dihydro-2,5-diphenyloxazol-4-yl)-
methanol, C16H15NO2, has been con®rmed as 4S,5S. The
hydroxymethyl group and phenyl ring at the asymmetric C
atoms exhibit ꢀ and ꢁ orientations, respectively. The exocyclic
CÐC bonds at the asymmetric C atoms are mutually anticlinal
( ac). The hydroxyl group and the N atom of the oxazoline
ring are involved in an intermolecular hydrogen bond leading
to chains of molecules.
Comment
The synthesis of the title compound, (II), from (1S,2S)-(+)-2-
amino-1-phenyl-1,3-propanediol, (I), and ethyl benzimidate
hydrochloride or benzonitrile has recently been reported
independently by three research groups (Allen & Williams,
1994; Hoarau et al., 1997; Rozwadowska, 1998). Although the
stereochemistry of (II) has been accepted as 4S,5S, the
samples of oxazoline (II) prepared in these laboratories
differed signi®cantly in their physical data, i.e. in speci®c
rotations, both in the sign and dimension, melting points and
solubility, whereas the spectral data were much the same,
within experimental error, for all the samples (see Experi-
mental).
oriented.
The
torsion
angle
C12ÐC4ÐC5ÐC14
[ 111.39 (13)ꢀ] indicates an anticlinal conformation of the
C12 atom in the hydroxymethyl group with respect to the C14
atom of the phenyl group.
Oxazoline (II), prepared in our laboratory from (I) and
ethyl benzimidate hydrochloride or benzonitrile, showed
positive rotation, as did the sample described by Hoarau et al.
(1997), whereas Allen & Williams (1994) reported negative
rotation. There were also differences in the melting points of
all the samples: our sample melted at a much higher
temperature (459±460 K) than the samples prepared by Allen
Figure 2
The hydrogen bonding in the crystal lattice of (II). The hydrogen bonds
are indicated with dashed lines and the symmetry codes are explained in
Table 2.
ꢁ
Acta Cryst. (2000). C56, 981±982
# 2000 International Union of Crystallography
Printed in Great Britain ± all rights reserved 981

organic compounds
Re®nement
The oxazoline ring is nearly planar with an r.m.s. deviation
Ê
different interplanar angles of 8.82 (10) and 82.47 (4)ꢀ,
respectively, to the oxazoline ring. The C2ÐC6 distance of
Re®nement on F2
R[F2 > 2ꢂ(F2)] = 0.029
wR(F2) = 0.082
S = 1.076
2406 re¯ections
233 parameters
All H-atom parameters re®ned
w = 1/[ꢂ2(Fo2) + (0.0536P)2
+ 0.0663P]
(Á/ꢂ)max < 0.001
of 0.0306 A. The C2 and C5 phenyl groups subtend very
3
Ê
Áꢆmax = 0.13 e A
3
Ê
0.13 e A
Áꢆmin
=
Extinction correction: SHELXL97
(Sheldrick, 1997)
Extinction coef®cient: 0.0047 (7)
Absolute structure: Flack (1983)
Flack parameter = 0.09 (19)
Ê
Ê
1.4723 (17) A is shorter than the C5ÐC14 single bond of
1.4999 (16) A by about 12ꢂ. This indicates a weak conjugation
effect between the C2 phenyl group and the oxazoline ring.
The bond distances and angles in the title molecule are
consistent with those found in (4S,5S,SS)-4-hydroxymethyl-2-
[2-(4-methylphenylsul®nyl)phenyl]-4,5-dihydro-5-phenyl-1,3-
oxazole (Bower et al., 1996). Other hydroxymethyl-phenyl-
oxazoline derivatives are not described in the Cambridge
Structural Database (Version 5.18; Allen & Kennard, 1993).
The O13 atom of the hydroxyl group is synclinal with
respect to the N3ÐC4 bond of the oxazoline ring [torsion
angle O13ÐC12ÐC4ÐN3 of 68.15 (14)ꢀ]. We assume that this
arrangement of the O13 atom is stabilized by the inter-
molecular O13ÐH13AÁ Á ÁN3i hydrogen bond (Table 2), which
leads to chains of molecules parallel to the x axis. An inter-
molecular C16ÐH16AÁ Á ÁO13ii contact (Table 2) links neigh-
2
2
where P = (Fo + 2Fc )/3
Table 1
Selected geometric parameters (A, ).
ꢀ
Ê
O1ÐC2
O1ÐC5
C2ÐN3
C2ÐC6
1.3563 (14)
1.4568 (16)
1.2677 (16)
1.4723 (17)
N3ÐC4
C4ÐC5
C5ÐC14
1.4660 (15)
1.5479 (16)
1.4999 (16)
C2ÐO1ÐC5
N3ÐC2ÐO1
C2ÐN3ÐC4
106.52 (9)
117.81 (10)
107.69 (9)
N3ÐC4ÐC5
O1ÐC5ÐC4
104.34 (10)
103.13 (9)
Table 2
Hydrogen-bonding geometry (A, ).
bouring chains into
a two-dimensional hydrogen-bond
ꢀ
Ê
network parallel to the xy plane (Fig. 2).
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
O13ÐH13AÁ Á ÁN3i
0.92 (2)
0.99 (2)
1.89 (2)
2.49 (2)
2.7948 (14)
3.3314 (18)
169 (2)
142.3 (16)
C16ÐH16AÁ Á ÁO13ii
Symmetry codes: (i) x
Experimental
1
2
3
2
1
2
;
y; z; (ii) ‡ x; 52 y; z.
The title compound, (II), was prepared according to the literature
procedure of Rozwadowska (1998). The crystals were grown from
ethanol by slow evaporation of the solvent at room temperature.
Some of physical and spectral characteristics of our sample and of the
others are given below:
The positions of the H atoms were obtained from difference
Fourier maps and re®ned freely. The absolute con®guration of (II)
was established on the basis of 930 Friedel opposite re¯ections using
the Flack parameter (Flack, 1983).
(II): m.p. 459±460 K; [ꢁ]D20 = +51.0 (c = 0.54, CHCl3), [ꢁ]2D0 = +70.0
(c = 0.5, CH3OH), [ꢁ]2D0 = +88.5 (c = 1.0, DMSO); IR (KBr) cm
:
1
Data collection, cell re®nement and data reduction: Kuma KM-4
Software (Kuma Diffraction, 1991); program(s) used to solve struc-
ture: SHELXS97 (Sheldrick, 1990); program(s) used to re®ne struc-
ture: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPII
(Johnson, 1976) and ORTEP-3 for Windows (Farrugia, 1997); soft-
ware used to prepare material for publication: SHELXL97.
1648 (C N); 1H NMR (CDCl3), p.p.m.: ꢃ = 4.24 (d, J = 8.0 Hz, H4),
5.58 (d, J = 8.2 Hz, H5).
Allen & Williams (1994): m.p. 400±402 K; [ꢁ]D25
CHCl3); IR (KBr) cm 1: 1670 (C N); 1H NMR (CDCl3), p.p.m.: ꢃ =
=
44.6 (c = 5.4,
4.22 (H4), 5.56 (d, J = 8.0 Hz, H5).
Hoarau et al. (1997): m.p. 408 K; [ꢁ]2D0 = +74.2 (c = 1,0, DMSO); 1H
NMR (CDCl3), p.p.m.: ꢃ = 4.23 (d, J = 8.1 Hz, H4), 5.57 (d, J = 8.1 Hz,
H5).
This work was supported by KBN grant No. 3 T09A 027 17.
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: JZ1397). Services for accessing these data are
described at the back of the journal.
Crystal data
C16H15NO2
Mr = 253.29
Orthorhombic, P212121
Ê
a = 4.8995 (10) A
Ê
b = 11.3300 (13) A
c = 23.820 (3) A
Ê
V = 1322.3 (4) A
Z = 4
Dx = 1.272 Mg m
Cu Kꢁ radiation
Cell parameters from 48
re¯ections
ꢄ = 15.4±30.3ꢀ
References
1
ꢅ = 0.674 mm
T = 293 (2) K
Allen, F. H. & Kennard, O. (1993). Chem. Des. Autom. News, 8, 31±37.
Allen, J. V. & Williams, J. M. J. (1994). Tetrahedron Asymmetry, 5, 277±282.
Bower, J. F., Martin, C. J., Rawson, D. J., Slawin, A. M. Z. & Williams, J. M. J.
(1996). J. Chem. Soc. Perkin Trans. 1, pp. 333±342.
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.
Flack, H. D. (1983). Acta Cryst. A39, 876±881.
Ê
3
Needle, colourless
0.50 Â 0.25 Â 0.11 mm
3
È
Hoarau, O., Aõt-Haddou, H., Castro, M. & Balavoine, G. G. A. (1997). Tetra-
hedron Asymmetry, 8, 3755±3764.
Data collection
Kuma Diffraction KM-4 diffract-
ometer
!±2ꢄ scans
2557 measured re¯ections
2406 independent re¯ections
2273 re¯ections with I > 2ꢂ(I)
Rint = 0.037
ꢄ
max = 70.04ꢀ
Johnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge National
Laboratory, Tennessee, USA.
Kuma Diffraction (1991). Kuma KM-4 User's Guide. Version 1991t. Kuma
Diffraction, Wrocøaw, Poland.
Rozwadowska, M. D. (1998). Tetrahedron Asymmetry, 9, 1615±1618.
Sheldrick, G. M. (1990). Acta Cryst. A46, 467±473.
È
Sheldrick, G. M. (1997). SHELXL97. University of Gottingen, Germany.
h = 5 ! 5
k = 0 ! 13
l = 0 ! 29
2 standard re¯ections
every 100 re¯ections
intensity decay: 0.7%
ꢁ
982 Gzella and Rozwadowska C16H15NO2
Acta Cryst. (2000). C56, 981±982