(P,M)-1,2,3,9,10,11 -Hexamethoxy-5,7-dihydrodibenz[c,e]oxepine and (P,M)-1,11 -dimethyl-5,5,7,7-tetraphenyl-5,7-dihydrodibenz[c,e]oxepine

Article abstract of DOI:10.1107/S010827010400294X

The crystallographic C₂ symmetry and seven-membered ring of C₂₀H₂₄O₇ and C₄₀H₃₂O were analyzed. Both the molecules were racemic oxepines which adopted twisted-boat conformations and contain

Full text of DOI:10.1107/S010827010400294X

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
symmetry, with the twofold axis passing through the middle of
the biphenyl bond (which corresponds with the C3ÐC4 bond
in the oxepine nomenclature) and the O atom of the seven-
membered ring. In compound (I), the H atoms of the methyl
group at atom C9 adopt two disordered nearly equally occu-
pied orientations, which differ by a rotation of the group by
approximately 50ꢀ.
ISSN 0108-2701
(P,M)-1,2,3,9,10,11-Hexamethoxy-
5,7-dihydrodibenz[c,e]oxepine and
(P,M)-1,11-dimethyl-5,5,7,7-tetra-
phenyl-5,7-dihydrodibenz[c,e]oxepine
The oxepine ring in both (I) and (II) adopts a twisted-boat
conformation, in which one OÐC bond and the opposing CÐ
C bond that is fused to one of the phenyl rings form the ¯oor
of the boat [for example, atoms C1, C2, O1 and C7(1 x, y,
1
2
z)]. The choice of OÐC bond is irrelevant because of the
molecular C2 symmetry. The angles between the planes
de®ned by this four-atom ¯oor and the three-atom bow plane
(atoms C2, C7 and O1) of the boat are 48.22 (12) and
44.03 (14)ꢀ for (I) and (II), respectively, while the angles
between the ¯oor and the four-atom stern [atoms C1,
C1(1 x, y, 12 z), C2(1 x, y, 21 z) and C7(1 x, y, 12 z)
for (I), similarly for (II)] of the boat are 52.66 (8) and
54.72 (1)ꢀ, respectively. In (I), the angle between the planes of
the biphenyl aromatic rings is 52.92 (6), whereas in (II), the
angle is almost 9ꢀ greater, at 61.47 (8)ꢀ. The latter is a rather
large angle for a biphenyl with a three-atom bridge and its
possible cause is discussed below.
The Cambridge Structural Database (CSD, January 2004
release; Allen, 2002) contains the details of seven structures of
5,7-dihydrodibenz[c,e]oxepines (no dinaphth[c,e]oxepines
were found). Two of these structures are transition-metal
complexes and so were discarded. Out of the remaining ®ve
structures, only two had peri substituents at the biphenyl
moiety (Schmid et al., 1988; Roszak et al., 1996). Both struc-
tures show a twisted-boat conformation; the angle between
the four-atom ¯oor and the three-atom bow plane is in the
range 44.0±50.1ꢀ, while the angle between the ¯oor and the
four-atom stern of the boat is in the range 54.1±55.5ꢀ. The
angle between the planes of the biphenyl aromatic rings in
Anthony Linden,* Markus Furegati and Andreas J. Rippert
Institute of Organic Chemistry, University of Zurich, Winterthurerstrasse 190,
È
CH-8057 Zurich, Switzerland
È
Correspondence e-mail: alinden@oci.unizh.ch
Received 4 February 2004
Accepted 5 February 2004
Online 11 March 2004
The title compounds, C20H24O7 and C40H32O, respectively,
are racemic oxepines, the molecules of which contain a
chiral axis. Both molecules possess crystallographic C2
symmetry and the seven-membered ring adopts a twisted-
boat conformation.
Comment
Molecules containing a chiral axis are becoming increasingly
important in asymmetric synthesis as chiral ligands or auxili-
aries (Spring et al., 2002), as well as being potential pharma-
ceuticals (Bringmann et al., 2002). During our investigation of
the synthesis of axially chiral amino alcohols by a simple ring-
opening reaction of substituted dibenzo[c,e]oxepines (Fure-
gati & Rippert, 2002), we obtained crystals of the title
compounds (I) and (II). As we are interested in the confor-
mation of dibenzo-annellated seven-membered rings and the
angle between the aromatic ring planes in general (Schneider
et al., 2000), and, in particular, in the orientation of the phenyl
substituents in the molecule of compound (II), we have
determined the crystal structures of the title compounds.
Figure 1
A view of the molecule of (I), showing the atom-labelling scheme.
Displacement ellipsoids are drawn at the 50% probability level and H
atoms are represented by circles of arbitrary size. Only one of the
In both (I) and (II), the bond lengths and angles are within
normal ranges. Both molecules possess crystallographic C2
disordered orientations of the C9 methyl H atoms is shown. [Symmetry
1
code: (i) 1 x, y,
z.]
2
Acta Cryst. (2004). C60, o223±o225
DOI: 10.1107/S010827010400294X
# 2004 International Union of Crystallography o223

organic compounds
Compound (I)
Crystal data
3
C20H24O7
Mr = 376.40
Monoclinic, C2=c
Dx = 1.401 Mg m
Mo Kꢁ radiation
Cell parameters from 2731
re¯ections
Ê
a = 15.3979 (3) A
b = 10.3781 (2) A
ꢂ = 2.0±30.0ꢀ
Ê
Ê
1
c = 11.8825 (3) A
ꢃ = 0.11 mm
T = 160 (1) K
ꢀ = 109.9789 (8)ꢀ
3
Ê
V = 1784.56 (7) A
Z = 4
Prism, colourless
0.25 Â 0.20 Â 0.10 mm
Data collection
Nonius KappaCCD area-detector
diffractometer
Rint = 0.042
ꢂmax = 30.0ꢀ
' and ! scans with ꢄ offsets
25 172 measured re¯ections
2607 independent re¯ections
1974 re¯ections with I > 2ꢅ(I)
h = 21 ! 21
k = 14 ! 14
l = 16 ! 16
Re®nement
Figure 2
A view of the molecule of (II), showing the atom-labelling scheme.
Re®nement on F2
R[F2 > 2ꢅ(F2)] = 0.044
wR(F2) = 0.130
S = 1.06
2605 re¯ections
w = 1/[ꢅ2(Fo2) + (0.0666P)2
+ 0.8193P]
Displacement ellipsoids are drawn at the 50% probability level and H
atoms are represented by circles of arbitrary size. [Symmetry code: (i)
where P = (Fo2 + 2Fc2)/3
(Á/ꢅ)max = 0.001
3
2
1
x, y,
z.]
3
Ê
Áꢆmax = 0.25 e A
3
Ê
0.21 e A
127 parameters
H-atom parameters constrained
Áꢆmin
=
these compounds is in the range 49.2±56.6ꢀ. All of these values
are very similar to those in compounds (I) and (II). In the
three structures having no substituents at the peri positions of
the biphenyl moiety (Nieger et al., 1998; Carey et al., 2002), the
outlined angles are again in similar ranges; ¯oor/bow: 39.5±
46.2ꢀ, ¯oor/stern: 48.1±52.5ꢀ and biphenyl ring plane angle:
46.2±50.4ꢀ. Although two of these structures have a similar
5,5,7,7-tetraphenyl substitution pattern to compound (II), the
angles between the planes of the biphenyl aromatic rings are
no larger than usual, unlike that in (II). Therefore, the tetra-
phenyl substitution pattern alone does not introduce suf®cient
steric constraints to cause an increase in the biphenyl plane
angle, but in combination with the addition of substituents at
the peri position of the biphenyl moiety, as in compound (II),
there is apparently suf®cient steric strain to cause a signi®cant
increase in this angle.
Compound (II)
Crystal data
C40H32O
Mr = 528.66
Orthorhombic, Pbcn
Mo Kꢁ radiation
Cell parameters from 2853
re¯ections
ꢂ = 2.0±25.0ꢀ
Ê
a = 16.6918 (4) A
1
Ê
b = 9.6863 (3) A
ꢃ = 0.07 mm
T = 160 (1) K
Ê
c = 17.5921 (5) A
3
Ê
V = 2844.32 (14) A
Prism, colourless
0.22 Â 0.15 Â 0.12 mm
Z = 4
Dx = 1.235 Mg m
3
Data collection
Nonius KappaCCD area-detector
diffractometer
' and ! scans with ꢄ offset
25 719 measured re¯ections
2507 independent re¯ections
1920 re¯ections with I > 2ꢅ(I)
Rint = 0.063
ꢂmax = 25.0ꢀ
h = 19 ! 19
k = 11 ! 11
l = 20 ! 20
A previous analysis of related dibenz- and dinaphthazepine
derivatives (Schneider et al., 2000), which have an N atom in
the seven-membered ring in place of the O atom, revealed
quite similar conformational properties for both the confor-
mation of the seven-membered ring and the angle between the
planes of the biphenyl (or binaphthyl) aromatic rings.
Re®nement
Re®nement on F2
R[F2 > 2ꢅ(F2)] = 0.045
wR(F2) = 0.129
S = 1.04
2502 re¯ections
188 parameters
(Á/ꢅ)max = 0.001
3
Ê
Áꢆmax = 0.25 e A
3
Ê
0.22 e A
Áꢆmin
=
Extinction correction: SHELXL97
(Sheldrick, 1997)
Extinction coef®cient: 0.011 (2)
H-atom parameters constrained
w = 1/[ꢅ2(Fo2) + (0.0767P)2
+ 0.6145P]
2
2
Experimental
where P = (Fo + 2Fc )/3
The title compounds can be synthesized almost quantitatively by
boiling the corresponding biphenyldiol in toluene for 12 h in the
presence of catalytic amounts of toluenesulfonic acid with the reac-
tion vessel connected to a water extractor (Wittig & Zimmermann,
1955). Compound (I) (m.p. 422 K) was crystallized from methyl tert-
butyl ether±toluene (95:5) and compound (II) (m.p. 576 K) was
crystallized from neat toluene.
For each structure, the methyl H atoms were constrained to an
Ê
ideal geometry (CÐH = 0.98 A), with Uiso(H) = 1.5Ueq(C), but were
allowed to rotate freely about the parent CÐO or CÐC bond. All
remaining H atoms were placed in geometrically idealized positions
Ê
(CÐH = 0.95±0.99 A) and constrained to ride on their parent atoms,
with Uiso(H) = 1.2Ueq(C). For (I), a difference Fourier map showed
ꢁ
o224 Anthony Linden et al.
C20H24O7 and C40H32O
Acta Cryst. (2004). C60, o223±o225

organic compounds
that the H atoms of the methyl group at atom C9 adopted two
disordered orientations which differ by a rotation of the group by
approximately 50ꢀ. Therefore, two idealized orientations were
de®ned for these H atoms and constrained re®nement of the site-
occupation factors led to a value of 0.55 (2) for the major confor-
mation. For (I) and (II), two and ®ve low-angle re¯ections, respec-
tively, had unexpectedly low intensities as a result of being partially
obscured by the beam stop and were omitted.
References
Allen, F. H. (2002). Acta Cryst. B58, 380±388.
Bringmann, G., Hinrichs, J., Henschel, P., Kraus, J., Peters, K. & Peters, E.-M.
(2002). Eur. J. Org. Chem. 6, 1096±1106.
Carey, K. A., Clegg, W., Elsegood, M. R. J., Golding, B. T., Hill, M. N. S. &
Maskill, H. (2002). J. Chem. Soc. Perkin Trans. 1, pp. 2673±2679.
Furegati, M. & Rippert, A. J. (2002). Synlett, pp. 1158±1160.
Johnson, C. K. (1976). ORTEPII. Report ORNL-5138. Oak Ridge National
Laboratory, Tennessee, USA.
Nieger, M., Hupfer, H. & Bolte, M. (1998). Acta Cryst. C54, 656±659.
Nonius (2000). COLLECT. Nonius BV, Delft, The Netherlands.
Otwinowski, Z. & Minor, W. (1997). Methods in Enzymology, Vol. 276,
Macromolecular Crystallography, Part A, edited by C. W. Carter Jr & R. M.
Sweet, pp. 307±326. New York: Academic Press.
Roszak, A. W., Williams, V. E. & Lemieux, R. P. (1996). Acta Cryst. C52, 3190±
3193.
È
Schmid, R., Cereghetti, M., Heiser, B., Schonholzer, P. & Hansen, H.-J. (1988).
Helv. Chim. Acta, 71, 897±929.
For both title compounds, data collection: COLLECT (Nonius,
2000); cell re®nement: DENZO±SMN (Otwinowski & Minor, 1997);
data reduction: DENZO±SMN and SCALEPACK (Otwinowski &
Minor, 1997); program(s) used to solve structure: SHELXS97
(Sheldrick, 1997); program(s) used to re®ne structure: SHELXL97
(Sheldrick, 1997); molecular graphics: ORTEPII (Johnson, 1976);
software used to prepare material for publication: SHELXL97 and
PLATON (Spek, 2004).
Schneider, M., Linden, A. & Rippert, A. J. (2000). Acta Cryst. C56, 1004±1006.
Sheldrick, G. M. (1997). SHELXS97 and SHELXL97. University of
È
Gottingen, Germany.
Spek, A. L. (2004). PLATON. University of Utrecht, The Netherlands.
Spring, D. R., Krishnan, S., Blackwell, H. E. & Schreiber, S. L. (2002). J. Am.
Chem. Soc. 124, 1354±1363.
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: SK1701). Services for accessing these data are
described at the back of the journal.
Wittig, G. & Zimmermann, H. (1955). Chem. Ber. 86, 627±637.
ꢁ
Acta Cryst. (2004). C60, o223±o225
Anthony Linden et al.
C20H24O7 and C40H32
O
o225