6-hydroxy-2,2-dimethyl-3,4-dihydro-2H-benzo[b]pyran

Article abstract of DOI:10.1107/S0108270100005813

The title compound, 2,2-dimethylchroman-6-ol, C₁₁H₁₄O₂, has been identified as a side product from the condensation of hydroquinone with 2-methylbut-3-en-2-ol. The pyran ring has a half-chair conformation. The hydroxyl groups are involved in intermolecular hydrogen bonding which generates infinite spiral chains around the fourfold screw axes; the O...O hydrogen-bonded distances are 2.661 (1) angstrom.

Full text of DOI:10.1107/S0108270100005813

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
ISSN 0108-2701
6-Hydroxy-2,2-dimethyl-3,4-dihydro-
2H-benzo[b]pyran
Figure 1
The atomic numbering for (I) with displacement ellipsoids at the 50%
probability level.
Amitabh Jha,a Sanjay Malhotra,a Virinder S. Parmara and
William Erringtonb*
aDepartment of Chemistry, University of Delhi, Delhi 110 007, India, and
bDepartment of Chemistry, University of Warwick, Coventry CV4 7AL, England
Correspondence e-mail: w.errington@warwick.ac.uk
The title compound has been reported brie¯y in an earlier
study (Mukai et al., 1993) concerned with the extent of orbital
overlap between the 2p lone pair on the ring oxygen with the
aromatic ꢂ-electron system in a series of related compounds. It
was argued that the larger this overlap, the smaller the C2Ð
O1ÐC9ÐC10 torsion angle. This torsion angle was given as
18.0ꢀ based upon an X-ray investigation and as 20.1ꢀ from ab
initio calculations; the value of 19.7 (2)ꢀ obtained in the
present study is in excellent agreement with that obtained
from the theoretical study.
Received 10 February 2000
Accepted 14 April 2000
The title compound, 2,2-dimethylchroman-6-ol, C11H14O2, has
been identi®ed as a side product from the condensation of
hydroquinone with 2-methylbut-3-en-2-ol. The pyran ring has
a half-chair conformation. The hydroxyl groups are involved
in intermolecular hydrogen bonding which generates in®nite
spiral chains around the fourfold screw axes; the OÁ Á ÁO
The hydroxyl O atoms form intermolecular hydrogen bonds
with two other molecules (Table 2 and Fig. 2), thus producing
in®nite polymeric spiral chains around the fourfold screw axes.
Ê
hydrogen-bonded distances are 2.661 (1) A.
Comment
Chromans are known to possess pronounced antioxidant
activity (Cotelle et al., 1991, 1992; Pearce et al., 1994). This
basic unit is also present in ꢀ-tocopherol which is a commer-
cial naturally occurring antioxidant. Such compounds are also
used as colour photographic recording materials (Fujiwhara et
al., 1978) and in pharmaceutical compositions (Evans et al.,
1981). We have prepared several chromanols for biotransfor-
mation studies for structure±activity relationship studies as
antitumour agents (Parmar et al., 1994, 1997). In one such
reaction, the title compound, (I), was obtained as a side
product during the condensation of hydroquinone with
2-methylbut-3-en-2-ol in the form of colourless crystals; its
structure was determined in order to assign its constitution
unambiguously.
The molecular structure is illustrated in Fig. 1 and selected
geometric parameters are given in Table 1. Bond lengths and
angles are largely unexceptional. An analysis (Cremer &
Pople, 1975; Farrugia, 1998) of the puckering in the six-
Figure 2
Packing diagram viewed down the c axis.
Ê
membered pyran ring gives a puckering amplitude of 0.485 A,
with ꢁ = 49.9 and ' = 85.95ꢀ; this corresponds to a half-chair
conformation. The C12 methyl group occupies an axial posi-
tion, whilst the H atoms are attached to C4 in axial and
bisectional orientations.
Experimental
To a stirred solution of hydroquinone (2.2 g, 20 mmol) and boron
tri¯uoride etherate (0.3 ml) in dioxane (15 ml) at 300 K, a solution of
2-methylbut-3-en-2-ol (2.6 g, 20 mmol) was added dropwise over
ꢁ
Acta Cryst. (2000). C56, 899±900
# 2000 International Union of Crystallography
Printed in Great Britain ± all rights reserved 899

organic compounds
30 min. The reaction mixture was stirred for a further hour at 300 K
and then quenched using moist ether; the mixture was diluted with
water (100 ml) and extracted with ether (3 Â 50 ml). The ether layer
was dried over anhydrous Na2SO4, the solvent was removed and the
residue chromatographed over silica gel to afford (I). It was recrys-
tallized from chloroform as colourless crystals [m.p. 348 K; literature
m.p. 348±349 K (Nilsson et al., 1968)].
The hydroxyl H atom was added from an electron-density map and
freely re®ned. Other H atoms were added at calculated positions and
re®ned using a riding model with CÐH distances in the range 0.95±
Ê
0.99 A. H atoms were given isotropic displacement parameters equal
to 1.2 (or 1.5 for methyl H atoms) times the equivalent isotropic
displacement parameter of their parent atoms.
Data collection: SMART (Siemens, 1994); cell re®nement: SAINT
(Siemens, 1994); data reduction: SAINT; program(s) used to solve
structure: SHELXTL/PC (Sheldrick, 1994); program(s) used to
re®ne structure: SHELXL97 (Sheldrick, 1997); molecular graphics:
SHELXTL/PC; software used to prepare material for publication:
SHELXTL/PC.
Crystal data
C11H14O2
Mo Kꢀ radiation
Cell parameters from 4204
re¯ections
Mr = 178.22
Tetragonal, I41=a
a = 25.1353 (12) A
c = 6.2139 (4) A
Ê
V = 3925.8 (4) A
ꢁ = 2.29±27.49ꢀ
Ê
1
Ê
ꢃ = 0.082 mm
T = 180 (2) K
3
We wish to acknowledge the use of the EPSRC's Chemical
Database Service at Daresbury Laboratory (Fletcher et al.,
1996) for access to the Cambridge Structural Database (Allen
& Kennard, 1993).
Z = 16
Dx = 1.206 Mg m
Block, colourless
0.30 Â 0.22 Â 0.20 mm
3
Data collection
Siemens SMART CCD area-
detector diffractometer
! scans
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
Tmin = 0.976, Tmax = 0.984
11 034 measured re¯ections
2237 independent re¯ections
1510 re¯ections with I > 2ꢄ(I)
Rint = 0.047
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: FR1268). Services for accessing these data are
described at the back of the journal.
ꢁ
max = 27.49ꢀ
h = 31 ! 32
k = 21 ! 32
l = 8 ! 6
References
Re®nement
Allen, F. H. & Kennard, O. (1993). Chem. Des. Autom. News, 8, 31±37.
Cotelle, N., Moreau, S., Bernier, J. L., Catteau, J. P. & Henichart, J. P. (1992).
Chem. Abstr. 116, 690.
Cotelle, N., Moreau, S., Cotelle, P., Catteau, J. P., Bernier, J. L. & Henichart, J. P.
(1991). Chem. Res. Toxicol. pp. 300±305.
Cremer, D. & Pople, J. A. (1975). J. Am. Chem. Soc. 97, 1354±1358.
Evans, J. M., Showell, G. A. & Fake, C. S. (1981). Chem. Abstr. 95, 115301.
Farrugia, L. J. (1998). WinGX. University of Glasgow, Scotland.
Fletcher, D. A., McMeeking, R. F. & Parkin, D. (1996). J. Chem. Inf. Comput.
Sci. 36, 746±749.
Re®nement on F2
R[F2 > 2ꢄ(F2)] = 0.047
wR(F2) = 0.115
S = 1.024
2237 re¯ections
124 parameters
H atoms treated by a mixture of
independent and constrained
re®nement
w = 1/[ꢄ2(Fo2) + (0.0488P)2
+ 1.8457P]
where P = (Fo2 + 2Fc2)/3
(Á/ꢄ)max < 0.001
3
Ê
Áꢅmax = 0.14 e A
3
Ê
0.24 e A
Áꢅmin
=
Fujiwhara, M., Sasaki, T. & Uchida, T. (1978). Chem. Abstr. 89, 14799.
Mukai, K., Ohbayashi, S., Nagaoka, S., Ozawa, T. & Azuma, N. (1993). Bull.
Chem. Soc. Jpn, 66, 3808±3810.
Nilsson, J. L. G., Silvertsson, H. & Selander, H. (1968). Acta Chem. Scand. 22,
3160±3170.
Table 1
Selected geometric parameters (A, ).
ꢀ
Ê
Parmar, V. S., Bracke, M. E., Philippe, J., Wengel, J., Jain, S. C., Olsen, C. E.,
Bisht, K. S., Sharma, N. K., Courtens, A., Sharma, S. K., Vennekens, K.,
Marck, V. V., Singh, S. K., Kumar, N., Kumar, A., Malhotra, S., Kumar, R.,
Rajwanshi, V. K., Jain, R. & Mareel, M. M. (1997). Bioorg. Med. Chem. 5,
1609±1619.
O1ÐC9
O1ÐC2
1.3805 (19)
1.4560 (19)
O2ÐC6
1.3873 (18)
O1ÐC2ÐC3ÐC4
C2ÐC3ÐC4ÐC10
61.43 (18)
43.3 (2)
C2ÐO1ÐC9ÐC10
C3ÐC4ÐC10ÐC9
19.7 (2)
13.3 (2)
Parmar, V. S., Jain, R., Sharma, S. K., Vardhan, A., Jha, A., Taneja, P., Singh, S.,
Vyncke, B. M., Bracke, M. E. & Mareel, M. M. (1994). J. Pharm. Sci. 83,
1217±1221.
Pearce, B. C., Parker, R. A., Deason, M. E., Dischino, D. D., Gillespie, E.,
Qureshi, A. A., Wright, J. J. K. & Volk, K. (1994). J. Med. Chem. 37, 526±
541.
Sheldrick, G. M. (1994). SHELXTL/PC. Version 5.0. Siemens Analytical
X-ray Instruments Inc., Madison, Wisconsin, USA.
Table 2
Hydrogen-bonding geometry (A, ).
ꢀ
Ê
DÐHÁ Á ÁA
O2ÐH2Á Á ÁO2i
DÐH
HÁ Á ÁA
1.77 (2)
DÁ Á ÁA
DÐHÁ Á ÁA
È
Sheldrick, G. M. (1996). SADABS. University of Gottingen, Germany.
Sheldrick, G. M. (1997). SHELXL97. University of Gottingen, Germany.
È
0.90 (2)
2.6608 (12)
172 (2)
Siemens (1994). SMART and SAINT. Version 4.021. Siemens Analytical X-ray
Instruments Inc., Madison, Wisconsin, USA.
3
4
Symmetry code: (i)
y; 14 ‡ x; 14 ‡ z.
ꢁ
900 Amitabh Jha et al. C11H14O2
Acta Cryst. (2000). C56, 899±900