6-(2-hydroxybenzoyl)-5-(pyrrol-2-yl)-3H-pyrrolizine

Article abstract of DOI:10.1107/S0108270103008394

The title compound, 2-hydroxyphenyl 5-(pyrrol-2-yl)-3H-pyrrolizin-6-yl ketone, C₁₈H₁₄N₂O₂, was isolated from the base-catalyzed 1:2 condensation of 2-hydroxyacetophenone with pyrrole-2-carbaldehyde. The pyrrole

Full text of DOI:10.1107/S0108270103008394

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
ISSN 0108-2701
6-(2-Hydroxybenzoyl)-5-(pyrrol-2-yl)-
3H-pyrrolizine
Sankar Prasad Dey,a Dilip Kumar Dey,b Asok Kumar
Mallikc and Lutz Dahlenburgd*
aDepartment of Chemistry, Srikrishna College, Bagalu 741 502, Nadia, West Bengal,
India, bDepartment of Chemistry, Chandidas Mahavidyalaya, Khujutipara 731 215,
Birbhum, West Bengal, India, cDepartment of Chemistry, Jadavpur University,
Kolkata 700 032, West Bengal, India, and dInstitut fur Anorganische Chemie,
È
Figure 1
View of (I), with ellipsoids at the 50% probability level. The
intramolecular hydrogen bonds are shown as double dashed lines.
Friedrich-Alexander-Universitat Erlangen-Nurnberg, Egerlandstraûe 1, D-91058
È
È
Erlangen, Germany
Correspondence e-mail: dahlenburg@chemie.uni-erlangen.de
Received 13 March 2003
Accepted 14 April 2003
Online 20 May 2003
2002). Pyrrolizines and their derivatives are of considerable
interest in view of both their occurrence as natural products
and their potential biological activities.
The title compound, 2-hydroxyphenyl 5-(pyrrol-2-yl)-3H-
pyrrolizin-6-yl ketone, C18H14N2O2, was isolated from the
base-catalyzed 1:2 condensation of 2-hydroxyacetophenone
with pyrrole-2-carbaldehyde. The pyrrole NÐH and hydroxy-
benzoyl OÐH groups are hydrogen bonded to the benzoyl O
atom. The allylic C C double bond of the 3H-pyrrolizine
system is located between ring positions 1 and 2, the C atom at
position 3 (adjacent to the N atom) being single bonded.
Although the basic structural features of the new
compounds could be established by detailed NMR studies
(Mallik et al., 2002), there remained some ambiguity with
respect to the exact position of the allylic C C double bond
in the 3H-pyrrolizine system, for which there exist two
conceivable alternatives, viz. either between ring positions 1
and 2 (see Scheme) or between the C atoms located at sites 2
and 3 (Jones, 1984). The X-ray structure analysis carried out
for the 1:2 condensation product (I), formed from 2-hy-
droxyacetophenone and pyrrole-2-carbaldehyde, showed the
allylic C C bond to be located between atoms C1 and C2
Comment
The base-catalyzed Claisen±Schmidt reaction between equi-
molar quantities of 2-hydroxyacetophenone and benzalde-
hyde is among the most common synthetic routes to 2-hy-
droxychalcone, a compound that is useful in the synthesis of
¯avonoid compounds (Geissman, 1962; Harborne et al., 1975;
Mallik et al., 1989, 1992). It has also been found that base-
catalyzed 1:2 condensations between 2-hydroxyacetophen-
ones and p-nitrobenzaldehyde in aqueous methanol gave
trans-2,3-dimethoxy-3-(p-formylphenylamino)-40-nitro¯avan-
ones as interesting novel products (Mallik et al., 1992).
Ê
[1.327 (3) A], atoms C2 and C3 of the 3H-pyrrolizine system
Ê
being connected by a single bond [1.493 (3) A]. The inter-
atomic distances within the CÐNÐC units of the unsaturated
bipyrrolyl part of the 5-(pyrrol-2-yl)-3H-pyrrolizine moiety,
viz. C4ÐN1ÐC7 and C8ÐN2ÐC11, span the relatively small
Ê
Ê
range 1.351 (3)±1.380 (2) A, which is about 0.14 A longer than
Ê
calculated for a C N double bond but ꢀ0.10 A shorter than
Ê
the value of 1.459 (2) A determined for the CÐN single bond
between C3 and N1. The substantial degree of ꢀ-electron
delocalization evidenced from these bond lengths is also
mirrored by the CÐC distances within the two unsaturated
®ve-membered rings, which are 1.422 (3), 1.432 (3) and
Ê
1.357 (3) A for the C4ÐC5ÐC6ÐC7 chain and 1.381 (3),
Ê
1.397 (3) and 1.360 (3) A for the C8ÐC9ÐC10ÐC11 chain
(Table 1).
The formation of two intramolecular hydrogen bonds, O1Ð
H1Á Á ÁO2 and N2ÐH2Á Á ÁO2 (Fig. 1 and Table 2), results in a
slightly skewed overall geometry for (I), which is best
described by the torsion angles given in Table 1 or by the
angles between the least-squares planes through the 3H-
pyrrolizine system (1), the pyrrole ring (2), and the o-hy-
droxybenzoyl building block (3) of 1±2 = 5.42 (11)ꢁ, 1±3 =
46.15 (5)ꢁ and 2±3 = 46.52 (7)ꢁ.
This encouraged us to study similar 1:2 condensations between
phenyl methyl ketones and pyrrole-2-carbaldehyde, from
which we obtained mixtures containing the usual (E)-1-acyl-3-
(pyrrol-2-yl)-2-propen-1-ones but also 6-acyl-5-(pyrrol-2-yl)-
3H-pyrrolizines as unexpected novel products (Mallik et al.,
Acta Cryst. (2003). C59, o321±o322
DOI: 10.1107/S0108270103008394
# 2003 International Union of Crystallography o321

organic compounds
Table 2
Hydrogen-bonding geometry (A, ).
Experimental
ꢁ
Ê
20% aqueous ethanolic KOH (10 ml) was added dropwise to a
mixture of 2-hydroxyacetophenone (1 mmol) and pyrrole-2-carbal-
dehyde (2 mmol) in ethanol (10 ml). After 4 d under ambient
conditions, the mixture was diluted with water (20 ml), carefully
acidi®ed by dropwise addition of 1 M HCl at 278 K, and subsequently
extracted with chloroform. Concentration of the chloroform extract
followed by chromatography over silica gel allowed the red
condensation product, (I), to be separated from orange (E)-1-(2-hy-
droxyphenyl)-3-(pyrrol-2-yl)-2-propen-1-one, which resulted from a
normal 1:1 Claisen±Schmidt condensation reaction (Mallik et al.,
2002). Single crystals were grown by slow evaporation of a chloro-
form±petroleum ether solvent mixture.
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
O1ÐH1Á Á ÁO2
N2ÐH2Á Á ÁO2
0.98 (3)
0.91 (2)
1.68 (3)
1.87 (2)
2.584 (2)
2.699 (2)
151 (2)
150 (2)
Re®nement
Re®nement on F2
R(F) = 0.043
wR(F2) = 0.113
S = 1.03
2499 re¯ections
208 parameters
H atoms treated by a mixture of
independent and constrained
re®nement
w = 1/[ꢅ2(Fo2) + (0.0518P)2
+ 0.2924P]
where P = (Fo2 + 2Fc2)/3
(Á/ꢅ)max = 0
3
Ê
Áꢆmax = 0.15 e A
3
Ê
0.15 e A
Áꢆmin
Extinction correction: SHELXL97
=
Crystal data
3
C18H14N2O2
Mr = 290.31
Monoclinic, P21/c
Dx = 1.37 Mg m
Mo Kꢂ radiation
Cell parameters from 25
re¯ections
Extinction coef®cient: 0.0134 (19)
Ê
a = 8.6868 (7) A
ꢃ = 8.4±12.7ꢁ
ꢄ = 0.09 mm
T = 293 (2) K
Ê
b = 22.0328 (13) A
With the exception of the hydroxy OÐH and pyrrole NÐH atoms
H1 and H2, which were allowed to re®ne freely, all H atoms were
re®ned in geometrically idealized positions employing a riding model
with isotropic displacement parameters constrained to 1.2 times Ueq
of their respective carrier atoms.
1
Ê
c = 7.592 (3) A
ꢁ = 104.407 (16)ꢁ
3
Ê
V = 1407.4 (6) A
Z = 4
Block, red
0.40 Â 0.15 Â 0.15 mm
Data collection
Data collection: CAD-4 EXPRESS (Enraf±Nonius, 1994); cell
re®nement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms &
Wocadlo, 1995); program(s) used to solve structure: SIR97 (Altomare
et al., 1999); program(s) used to re®ne structure: SHELXL97 (Shel-
drick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia,
1997); software used to prepare material for publication: WinGX
(Farrugia, 1999).
Nonius MACH3 diffractometer
Non-pro®led ! scans
2666 measured re¯ections
2499 independent re¯ections
1796 re¯ections with I > 2ꢅ(I)
Rint = 0.022
h = 10 ! 0
k = 26 ! 0
l = 8 ! 9
3 standard re¯ections
frequency: 60 min
intensity decay: 1%
ꢃmax = 25.2ꢁ
Table 1
Selected geometric parameters (A, ).
ꢁ
Ê
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: FA1012). Services for accessing these data are
described at the back of the journal.
O1ÐC12
O2ÐC18
N1ÐC4
N1ÐC7
N1ÐC3
N2ÐC11
N2ÐC8
C1ÐC2
C1ÐC7
C2ÐC3
1.358 (3)
1.258 (2)
1.356 (2)
1.380 (2)
1.459 (2)
1.351 (3)
1.373 (2)
1.327 (3)
1.445 (3)
1.493 (3)
C4ÐC5
C4ÐC8
C5ÐC6
C5ÐC18
C6ÐC7
C8ÐC9
C9ÐC10
C10ÐC11
C17ÐC18
1.422 (3)
1.445 (3)
1.432 (3)
1.446 (3)
1.357 (3)
1.381 (3)
1.397 (3)
1.360 (3)
1.481 (3)
References
Altomare, A., Burla, M. C., Camalli, M., Cascarano, G., Giacovazzo, C.,
Guagliardi, A., Moliterni, A. G. G., Polidori, G. & Spagna, R. (1999). J.
Appl. Cryst. 32, 115±119.
Enraf±Nonius (1994). CAD-4 EXPRESS. Enraf±Nonius, Delft, The Nether-
lands.
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.
Farrugia, L. J. (1999). J. Appl. Cryst. 32, 837±838.
Geissman, T. A. (1962). Editor. Chemistry of the Flavonoid Compounds, pp.
156±196. Oxford: Pergamon Press.
Harborne, J. B., Mabry, T. J. & Mabry, H. (1975). Editors. The Flavonoids, pp.
127±213. London: Chapman and Hall.
Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.
Jones, R. A. (1984). In Comprehensive Heterocyclic Chemistry, Vol. 4, edited
by A. R. Katritzky & C. W. Rees, pp. 295±296. Oxford: Pergamon Press.
Mallik, A. K., Dey, S. P., Chattopadhyay, F. & Patra, A. (2002). Tetrahedron
Lett. 44, 1295±1297.
C4ÐN1ÐC7
C4ÐN1ÐC3
C7ÐN1ÐC3
C11ÐN2ÐC8
C2ÐC1ÐC7
C1ÐC2ÐC3
N1ÐC3ÐC2
N1ÐC4ÐC5
N1ÐC4ÐC8
C5ÐC4ÐC8
C4ÐC5ÐC6
C4ÐC5ÐC18
C6ÐC5ÐC18
111.59 (15)
137.01 (16)
111.40 (15)
110.24 (18)
108.72 (19)
111.82 (18)
100.95 (16)
105.56 (16)
120.28 (16)
134.09 (17)
107.42 (16)
128.38 (17)
124.08 (17)
C7ÐC6ÐC5
C6ÐC7ÐN1
C6ÐC7ÐC1
N1ÐC7ÐC1
N2ÐC8ÐC9
N2ÐC8ÐC4
C9ÐC8ÐC4
C8ÐC9ÐC10
C11ÐC10ÐC9
N2ÐC11ÐC10
O2ÐC18ÐC5
O2ÐC18ÐC17
C5ÐC18ÐC17
107.30 (17)
108.12 (16)
144.8 (2)
107.09 (17)
106.17 (17)
123.06 (17)
130.74 (18)
107.96 (18)
107.59 (19)
108.04 (19)
121.90 (18)
117.63 (17)
120.43 (17)
Mallik, A. K., Saha, M. M. & Mallik, A. K. (1989). Indian J. Chem. Sect. B, 28,
970±972.
Mallik, A. K., Saha, M. M., Mallik, U. K., Goswami, S., McPhail, D. R. &
MacPhail, A. T. (1992). J. Chem. Soc. Chem. Commun. pp. 130±132.
È
Sheldrick, G. M. (1997). SHELXL97. University of Gottingen, Germany.
N1ÐC4ÐC8ÐN2
178.23 (17)
C4ÐC5ÐC18ÐC17
162.63 (19)
ꢂ
o322 Sankar Prasad Dey et al.
C18H14N2O2
Acta Cryst. (2003). C59, o321±o322