Efficient synthesis of functionalized 2,5-dihydropyrrole derivatives by Ph3P-promoted condensation between acetylene esters and α-arylamino ketones

Article abstract of DOI:10.1055/s-0029-1217516

A new and efficient one-pot synthesis of polysubstituted 2,5-dihydropyrrole derivatives by reaction between dialkyl acetylenedicarboxylates and β-aminoketones promoted by triphenylphosphine, is described. The prepared 2,5-dihydropyrroles can be easily oxi

Full text of DOI:10.1055/s-0029-1217516

LETTER
1929
Efficient Synthesis of Functionalized 2,5-Dihydropyrrole Derivatives by Ph3P-
Promoted Condensation between Acetylene Esters and a-Arylamino Ketones
S
ynthesis of Functiona
o
lized 2,5-Dih
h
ydropyrrole
a
D
erivative
m
s
mad Anary-Abbasinejad,* Ehsanorreza Poorhassan, Alireza Hassanabadi
Department of Chemistry, Islamic Azad University, Yazd Branch, PO Box 89195-155, Yazd, Iran
Fax +98(351)8211109; E-mail: mohammadanary@yahoo.com
Received 28 December 2008
reaction of dialkyl acetylenedicarboxylates, a-arylamino-
Abstract: A new and efficient one-pot synthesis of polysubstituted
2,5-dihydropyrrole derivatives by reaction between dialkyl acetyl-
enedicarboxylates and b-aminoketones promoted by triphenyl-
phosphine, is described. The prepared 2,5-dihydropyrroles can be
easily oxidized to the corresponding pyrrole derivatives by chromi-
um trioxide.
ketones and triphenylphosphine.
Thus, reaction between dimethyl acetylenedicarboxylate
(2; DMAD), 1-(4-bromophenyl)-2-(4-methoxyphenyl-
amino)ethanone (1a) and triphenylphosphine in dichlo-
romethane at room temperature after 24 hours, afforded
dimethyl 4-(4-bromophenyl)-1-(4-methoxyphenyl)-2,4-
dihydro-1H-pyrrole-2,3-dicarboxylate (3a) in 90%
yield.16 Under similar conditions, different 2,5-dihydro-
pyrrole derivatives were obtained using different deriva-
tives of acetylene diesters and a-aminoketones (Table 1).
Key words: 2,5-dihydropyrroles, dialkyl acetylenedicarboxylates,
b-aminoketones, triphenylphosphine, intramolecular Wittig reac-
tion
The development of simple synthetic routes for widely
used organic compounds from readily available reagents
is one of the major tasks in organic synthesis.1 2,5-Dihy-
dropyrroles are important compounds which exhibit a
wide range of biological activities and are useful interme-
diates in synthesizing natural products. Some 2,4-bisaryl-
2,5-dihydropyrrole derivatives have been recently studied
as novel, water-soluble KSP inhibitors.2 2,5-Bisaryl-2,5-
dihydropyrrole derivatives are part of an important class
of photochromic compounds and often exhibit excellent
photochromic properties, thermal and photochemical sta-
bility and very good fatigue resistance for photochemical
reversibility.3 In addition, their herbicidal,4 pesticidal,5
and anti-tumor6 activities increasingly necessitate new re-
search in order to simplify the synthesis of these materials.
Despite their wide application range, available routes for
the synthesis of 2,5-dihydropyrroles are limited. Previous
syntheses of 2,5-dihydropyrroles utilized the Birch-reduc-
tion of electron-deficient pyrroles,7 ring-closing meta-
thesis (RCM) reactions,8 1,3-dipolar cycloaddition of
azomethine ylides to 2-(p-tolylsulfinile)acrylate,9 and
TiCl4/Zn promoted reductive cyclization of N,N-bis(2-
aryl-2-oxoethyl)anilines.3 Intramolecular Wittig reaction
of the intermediates generated by the three-component ad-
dition reaction of activated acetylenes, triphenylphos-
phine and 2-amino carbonyl compounds has been recently
used for the synthesis of five-membered nitrogen hetero-
cycles.10–12 In a continuation of our work on the reaction
between trivalent phosphorus nucleophiles and electron-
deficient acetylenic compounds in the presence of organic
N-H acidic compounds,13–15 here we wish to report an ef-
ficient, simple and one-pot synthetic method for some N-
substituted 2,5-dihydropyrrole derivatives through the
The structures of compounds 3a–h were deduced from
1
their elemental analyses and their IR, H, and 13C NMR
spectra. The mass spectra of these 2,5-dihydropyrroles
were fairly similar and displayed molecular ion peaks.
The 500 MHz 1H NMR spectrum of compound 3a exhib-
ited three sharp signals at d = 3.70, 3.73 and 3.75 ppm
arising from the three methoxy groups. The 2,5-dihydro-
pyrrole ring displayed an ABX pattern for the 2-CH and
the 5-CH2 spin system, with the geminal methylene
protons resonating as two double doublets at d = 4.50
(JH–H = 15.7 Hz, JH–H = 2.3 Hz) and 4.72 (JH–H = 15.7 Hz,
JH–H = 6.5 Hz) and the methine proton as a double doublet
at d = 5.39 (JH–H = 6.5 Hz, JH–H = 2.3 Hz). Aromatic pro-
tons showed two para-substituted phenyl ring patterns;
four 2 H doublets were observed at d = 6.63 (JH–H = 8.9
Hz), 6.85 (JH–H = 8.9 Hz), 7.35 (JH–H = 8.4 Hz), and 7.55
(JH–H = 8.4 Hz). In agreement with the proposed structure,
the 13C NMR spectrum of compound 3a showed sixteen
distinct resonances. The structural assignments made on
the basis of the NMR spectra of compound 3a were also
supported by its IR spectrum; the ester carbonyl groups
exhibited strong absorption bands at 1740 and 1699 cm–1.
A plausible mechanism for formation of compounds 3 is
illustrated in Scheme 1. On the basis of the well-
established chemistry of trivalent phosphorus nucleo-
philes,17–22 it is reasonable to assume that 2,5-dihydro-
pyrrole
3 resulted from the initial addition of
triphenylphosphine to the acetylene diester and subse-
quent protonation of the 1:1 adduct by a-aminoketones.
Then, the positively charged ion intermediate 4 is attacked
by the conjugate anion of a-aminoketones 5 to form the
phosphorane 6, which is converted into product 3 through
an intramolecular Wittig reaction.
To examine the ease of oxidation of the prepared 2,5-di-
hydropyrrole derivatives to the corresponding pyrroles,
we carried out the reaction of a selection of substrates with
SYNLETT 2009, No. 12, pp 1929–1932
Advanced online publication: 25.06.2009
DOI: 10.1055/s-0029-1217516; Art ID: D42508ST
© Georg Thieme Verlag Stuttgart · New York
x
x
.x
x
.2
0
0
9

1930
M. Anary-Abbasinejad et al.
LETTER
Table 2 Oxidation of 2,5-Dihydropyrrole Derivatives to the Corre-
sponding Pyrroles by CrO3
Table 1 Reaction between Dialkyl Acetylenedicarboxylate and
a-Aminoketones in the Presence of Triphenylphosphine
Ar1
CO2Me
Ar1
CO2Me
CrO3
CHCl3, r.t., 4 h
CO2Me
CO2Me
N
N
Ar2
Ar2
3
7
Product
Ar1
Ar2
Yield of 7 (%)a
7a
7b
7c
Ph
4-MeOC6H4
83
85
80
Ph
4-MeC6H4
Product Ar1
Ar2
R
Yieldof3
4-BrC6H4
4-MeOC6H4
(%)a
a Isolated yield.
3a
3b
3c
3d
3e
3f
4-BrC6H4
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
4-MeOC6H4
4-ClC6H4
Me
Et
95
95
90
95
94
90
89
90
hydropyrroles can be easily oxidized to the corresponding
pyrrole derivatives by chromium trioxide. Advantages of
the reported method are that the reactions can be per-
formed under neutral conditions and that the readily avail-
able starting materials can be mixed without any further
purification or activation.
4-BrC6H4
4-ClC6H4
4-ClC6H4
4-BrC6H4
Ph
Me
Et
t-Bu
Me
Me
Me
References and Notes
3g
3h
Ph
(1) Laszlo, P. Organic Reactions: Simplicity and Logic; Wiley:
New York, 1995.
Ph
a Isolated yield.
(2) Garbaccio, R. M.; Fraley, M. E.; Tasber, E. S.; Olson, C. M.;
Hoffman, w. F.; Arrington, K. L.; Torrent, M.; Buser, C. A.;
Walsh, E. S.; Hamilton, K.; Schaber, M. D.; Fernandes, C.;
Lobell, R. B.; Tao, W.; South, V. J.; Yan, Y.; Kuo, L. C.;
Prueksaritanont, T.; Slaughter, D. E.; Shu, C.; Heimbrook,
D. C.; Kohl, N. E.; Huber, H. E.; Hartman, G. D. Bioorg.
Med. Chem. Lett. 2006, 16, 1780.
CO2R
Ph3P
O
H
+PPh3
CO2R
N–
O
Ar1
Ar2
CO2R
Ar2
3
– OPPh3
N
CO2R
Ar1
(3) Chen, Y.; Zeng, D. Z.; Xie, N.; Dang, Y. Z. J. Org. Chem.
4
5
6
2005, 70, 5001.
(4) Hinio, T. K.; Machida, T. G.; Hino, A. K.; Oume, A. Y.;
Hachioji, H. M. U.S. Patent 4,909,828, 1990.
(5) Bohner, B.; Baumann, M. U.S. Patent 4,220,655, 1980.
(6) Tarnavsky, S. S.; Dubinina, G. G.; Golovach, S. M.;
Yarmoluk, S. M. Biopolym. Cell 2003, 19, 548.
(7) Banks, C. E.; Evans, R. G.; Rodrigues, J.; Turner, P. G.;
Donohoe, T. J.; Compton, R. G. Tetrahedron 2005, 61,
2365.
(8) Kim, J. M.; Lee, K. Y.; Lee, S.; Kim, J. N. Tetrahedron Lett.
2004, 45, 2805.
(9) Ruano, J. L. G.; Tito, A.; Peromingo, M. T. J. Org. Chem.
2003, 68, 10013.
Scheme 1 Suggested mechanism for formation of compound 3
chromium trioxide. Thus, treatment of dimethyl 4-phenyl-
1-(4-methoxyphenyl)-2,4-dihydro-1H-pyrrole-2,3-dicar-
boxylate (3f) with chromium trioxide in chloroform at
room temperature for five hours, and separation by col-
umn chromatography, led to dimethyl 4-phenyl-1-(4-
methoxyphenyl)pyrrole-2,3-dicarboxylate (7a) in 83%
yield.23 Under similar conditions, pyrrole derivatives 7b
and 7c were obtained, respectively, from the oxidation of
2,5-dihydropyrrole derivatives 3g and 3a, in good yields
(Table 2). The 1H NMR spectrum of compound 7a exhib-
ited three sharp signals at d = 3.76, 3.86 and 3.88 ppm
arising from three methoxyl groups. A singlet (1 H) was
observed at d = 7.10 ppm, arising from the CH of the pyr-
role ring. Aromatic protons resonated between d = 6.98
and 7.30 ppm.
(10) Yavari, I.; Moradi, L.; Nasiri, F.; Djahaniani, H. Monatsh.
Chem. 2005, 136, 1757.
(11) Yavari, I.; Ahmadian-Razlighi, L. Phosphorus, Sulfur
Silicon 2006, 181, 771.
(12) Evans, L. A.; Griffiths, K. E.; Guthmann, H.; Murphy, P. J.
Tetrahedron Lett. 2002, 43, 299.
(13) Anary-Abbasinejad, M.; Anaraki-Ardakani, H.; Hosseini-
Mehdiabad, H. Phosphorus, Sulfur Silicon Relat. Elem.
2008, 183, 1440.
In conclusion, we have defined a new, efficient, simple,
and one-pot approach to some polysubstituted 2,5-dihy-
dropyrrole derivatives through a reaction between dialkyl
acetylenedicarboxylates and b-aminoketones promoted
by triphenylphosphine. Furthermore, the prepared 2,5-di-
(14) Anary-Abbasinejad, M.; Mosslemin, M. H.; Hassanabadi,
A.; Tabatabaee, M. Synth. Commun. 2008, 38, 3700.
(15) Anary-Abbasinejad, M.; Hassanabadi, A.; Anaraki-
Ardakani, H. J. Chem. Res. 2007, 455.
(16) General procedure for the preparation of compounds 3a–h:
To a magnetically stirred solution of b-aminoketone (1 mmol)
Synlett 2009, No. 12, 1929–1932 © Thieme Stuttgart · New York

LETTER
Synthesis of Functionalized 2,5-Dihydropyrrole Derivatives
1931
and triphenylphosphine (0.28 g, 1 mmol) in CH2Cl2 (10 mL),
(6 × CH3), 55.6, 55.7 (2 × OCH3), 60.7 (CH2), 71.1 (CH),
81.4 and 81.8 (2 × OC), 112.9, 115.0, 124.5, 127.2, 128.6,
129.5, 131.4, 134.9, 139.9, 147.8 and 151.9 (aromatic and
olefinic carbons), 161.9 and 171.8 (2 × CO ester). 3f:
Viscose oil; IR (KBr): 1733, 1711 (ester) cm–1; Anal. Calcd
for C21H21NO5: C, 68.65; H, 5.76; N, 3.81. Found: C, 68.88;
H, 5.66; N, 3.94. MS: m/z (%) = 367 (23). 1H NMR (500
MHz, CDCl3): d = 3.50, 3.57 and 3.59 (9 H, 3 × s, 3 ×
OCH3), 4.36 (1 H, dd, J = 15.6 Hz, J = 2.4 Hz, HCH), 4.58
(1 H, dd, J = 15.6 Hz, J = 6.4 Hz, HCH), 5.23 (1 H, dd,
J = 6.4 Hz, J = 2.4 Hz, CH), 6.48 and 6.62 (4 H, 2 × d,
J = 8.8 Hz, ArH), 7.23–7.55 (5 H, m, C6H5); 13C NMR
(125.8 MHz, CDCl3): d = 51.2, 52.4 and 52.7 (3 × OCH3),
60.8 (CH2), 69.9 (CH), 113.7, 115.8, 124.3, 124.9, 128.5,
129.1, 131.0, 139.8, 150.7 and 151.9 (aromatic and olefinic
carbons), 163.1 and 173.7 (2 × CO ester). 3g: Viscose oil; IR
(neat): 1735, 1707 (ester) cm–1; Anal. Calcd for C21H21NO4:
C, 71.78; H, 6.02; N, 3.99. Found: C, 71.70; H, 5.78; N, 3.72;
MS: m/z (%) = 351 (31); 1H NMR (500 MHz, CDCl3): d =
2.33 (3 H, s, CH3), 3.66 and 3.71 (6 H, 2 × s, 2 × OCH3), 4.57
(1 H, dd, J = 15.8 Hz, J = 2.3 Hz, HCH), 4.76 (1 H, dd,
J = 15.8 Hz, J = 6.4 Hz, HCH), 5.45 (1 H, dd, J = 6.4 Hz,
J = 2.3 Hz, CH), 7.23–7.59 (9 H, m, ArH). 13C NMR (125.8
MHz, CDCl3): d = 21.6 (CH3), 52.2, 52.9 (2 × OCH3), 61.0
(CH2), 70.0 (CH), 112.2, 124.5, 127.2, 128.5, 128.6, 128.9,
129.9, 130.5, 143.5, 152.3 (aromatic and olefinic carbons),
164.3, 172.4 (2 × CO ester). 3h: Viscose oil; IR (neat): 1732,
1695 (ester) cm–1; Anal. Calcd for C20H18ClNO4: C, 64.61;
H, 4.88; N, 3.77. Found: C, 64.79; H, 4.80; N, 3.90; MS:
m/z (%) = 371 (27); 1H NMR (500 MHz, CDCl3): d = 3.69
and 3.74 (6 H, 2 × s, 2 × OCH3), 4.55 (1 H, dd, J = 15.7 Hz,
J = 2.0 Hz, HCH), 4.75 (1 H, dd, J = 15.7 Hz, J = 6.2 Hz,
HCH), 5.41 (1 H, dd, J = 6.2 Hz, J = 2.0 Hz, CH), 6.61 and
7.2 (4 H, 2 × d, J = 8.9 Hz, C6H4Cl), 7.40–7.48 (5 H, m,
C6H5); 13C NMR (125.8 MHz, CDCl3): d = 52.2 and 53.0 (2
× OCH3), 60.9 (CH2), 70.0 (CH), 113.3, 115.7, 123.1, 124.4,
128.5, 128.6, 129.8, 130.0, 144.2 and 151.0 (aromatic and
olefinic carbons), 163.5 and 171.7 (2 × CO ester).
was added dropwise a mixture of dialkyl acetylenedicar-
boxylate (1 mmol) in CH2Cl2 (5 mL) at room temperature.
The reaction mixture was stirred for 24 h, then the solvent
was removed under reduced pressure and the residue was
purified by silica gel column chromatography (hexane–
EtOAc). The solvent was removed under reduced pressure to
afford the product.
3a: White powder; mp 110–112 °C; IR (KBr): 1740, 1699
(ester) cm–1; Anal. Calcd for C21H20BrNO5: C, 56.52; H,
4.52; N, 3.14. Found: C, 56.51; H, 4.33; N, 3.17; MS: m/z
(%) = 445 (4); 1H NMR (500 MHz, CDCl3): d = 3.70, 3.73
and 3.75 (9 H, 3 × s, 3 × OCH3), 4.50 (1 H, dd, J = 15.7 Hz,
J = 2.3 Hz, HCH), 4.72 (1 H, dd, J = 15.7 Hz, J = 6.5 Hz,
HCH), 5.39 (1 H, dd, J = 6.5 Hz, J = 2.3 Hz, CH), 6.63 and
6.85 (4 H, 2 × d, J = 8.9 Hz, ArH), 7.35 and 7.55 (4 H, 2 × d,
J = 8.4 Hz, ArH); 13C NMR (125.8 MHz, CDCl3): d = 52.3,
52.9 and 56.2 (3 × OCH3), 61.3 (CH2), 70.3 (CH), 113.1,
115.6, 124.2, 125.3, 130.2, 131.8, 131.9, 140.1, 151.2 and
152.6 (aromatic and olefinic carbons), 163.5 and 172.1 (2 ×
CO ester). 3b: Viscose oil; IR (neat): 1726 (ester) cm–1;
Anal. Calcd for C23H24BrNO5: C, 58.24; H, 5.10; N, 2.95.
Found: C, 58.10; H, 5.29; N, 2.78; MS: m/z (%) = 473 (11);
1H NMR (500 MHz, CDCl3): d = 1.20 (6 H, m, 2 × CH3),
3.73 (3 H, s, OCH3), 4.14 (4 H, m, 2 × OCH2), 4.77 (1 H, dd,
J = 15.6 Hz, J = 2.3 Hz, HCH), 4.71 (1 H, dd, J = 15.6 Hz,
J = 6.5 Hz, HCH), 5.38 (1 H, dd, J = 6.5 Hz, J = 2.3 Hz,
CH), 6.66 and 6.85 (4 H, 2 × d, J = 9.0 Hz, 4 H, ArH), 7.36
and 7.52 (4 H, 2 × d, J = 8.5 Hz, ArH); 13C NMR (125.8
MHz, CDCl3): d = 23.2 and 24.2 (2 × CH3), 55.9 (OCH3),
61.2, 61.3 and 61.7 (3 × OCH2), 70.4 (CH), 113.2, 115.5,
124.0, 126.2, 129.9, 130.3, 132.0, 140.1, 150.8 and 152.6
(aromatic and olefinic carbons), 162.9 and 171.7 (2 × CO
ester). 3c: White powder; mp 114–116 °C; IR (KBr): 1735,
1709 (ester) cm–1; Anal. Calcd for C21H20ClNO5: C, 62.77;
H, 5.02; N, 3.49. Found: C, 62.91; H, 5.17; N, 3.33; MS: m/
z (%) = 401 (27); 1H NMR (500 MHz, CDCl3): d = 3.51, 3.54
and 3.57 (9 H, 3 × s, 3 × OCH3), 4.33 (1 H, dd, J = 15.6 Hz,
J = 2.4 Hz, HCH), 4.53 (1 H, dd, J = 15.6 Hz, J = 6.4 Hz,
HCH), 5.21 (1 H, dd, J = 6.4 Hz, J = 2.4 Hz, CH), 6.45 and
6.68 (4 H, 2 × d, J = 8.8 Hz, ArH), 7.18–7.25 (4 H, m,
C6H4Cl); 13C NMR (125.8 MHz, CDCl3): d = 51.8, 52.4 and
52.7 (3 × OCH3), 60.9 (CH2), 69.9 (CH), 112.7, 115.2, 124.8,
128.5, 129.6, 131.0, 135.5, 139.8, 150.8 and 152.2 (aromatic
and olefinic carbons), 163.1 and 173.7 (2 × CO ester). 3d:
Viscose oil; IR (neat): 1730, 1710 (2 × CO ester) cm–1; Anal.
Calcd for C23H24ClNO5: C, 64.26; H, 5.63; N, 3.26. Found:
C, 64.20; H, 5.54; N, 3.37; MS: m/z (%) = 429 (25); 1H NMR
(500 MHz, CDCl3): d = 1.01, 1.04 (6 H, 2 × t, J = 7.4 Hz, 2
× CH3), 3.51 (4 H, m, 2 × OCH2), 3.57 (3 H, s, OCH3), 4.32
(1 H, dd, J = 15.6 Hz, J = 2.4 Hz, HCH), 4.53 (1 H, dd,
J = 15.6 Hz, J = 6.4 Hz, HCH), 5.20 (1 H, dd, J = 6.4 Hz,
J = 2.4 Hz, CH), 6.45 and 6.67 (4 H, 2 × d, J = 8.8 Hz,
C6H4OCH3), 7.18–7.26 (4 H, m, C6H4Cl); 13C NMR (125.8
MHz, CDCl3): d = 14.1 and 14.2 (2 × CH3), 55.4 (OCH3),
60.8, 60.9 and 61.3 (3 × CH2), 68.2 (CH), 112.8, 114.2,
115.1, 122.6, 125.3, 128.4, 129.7, 131.2, 135.3, 139.7, 150.4
and 152.1 (aromatic and olefinic carbons), 162.6 and 171.5
(2 × CO ester). 3e: Viscose oil; IR (neat): 1734, 1715 (2 ×
CO ester) cm–1; Anal. Calcd for C27H32ClNO5: C, 66.73; H,
6.64; N, 2.88. Found: C, 66.91; H, 6.61; N, 2.73. MS: m/z
(%) = 485 (9); 1H NMR (500 MHz, CDCl3): d = 1.19 and
1.21 (18 H, 2 × s, 6 × CH3), 4.25 (1 H, dd, J = 15.6 Hz,
J = 2.4 Hz, HCH), 4.45 (1 H, dd, J = 15.6 Hz, J = 6.4 Hz,
HCH), 5.05 (1 H, dd, J = 6.4 Hz, J = 2.4 Hz, CH), 6.45 and
6.66 (4 H, 2 × d, J = 9.0 Hz, C6H4OCH3), 7.00–7.20 (4 H, m,
C6H4Cl); 13C NMR (125.8 MHz, CDCl3): d = 27.9 and 29.8
(17) Corbridge, D. E. C. Phosphorus: An Outline of its
Chemistry, Biochemistry, and Uses, 5th ed.; Elsevier:
Amsterdam, 1995.
(18) Engel, R. Synthesis of Carbon–Phosphorus Bonds; CRC
Press: Boca Raton FL, 1988.
(19) Kolodiazhnyi, O. I. Russ. Chem. Rev. 1997, 66, 225.
(20) Bestmann, H. J.; Zimmermann, R. Top. Curr. Chem. 1983,
109, 85.
(21) Maryano, B. E.; Reits, A. B. Chem. Rev. 1989, 89, 863.
(22) Pietrusiewiz, K. M.; Zablocka, M. Chem. Rev. 1994, 94,
1375.
(23) General procedure for the preparation of compounds 7a–c:
To a magnetically stirred solution of dihydropyrrole
derivative 3 (1 mmol) in CHCl3 (10 mL), was added CrO3 (1
mmol) at room temperature. The reaction mixture was
stirred for 4 h, then the solvent was removed under reduced
pressure and the residue was purified by silica gel column
chromatography (hexane–EtOAc). The solvent was
removed under reduced pressure to afford the product.
7a: White powder; mp 123–125 °C; IR (KBr): 1740, 1707
(ester) cm–1; Anal. Calcd for C21H19NO5: C, 69.03; H, 5.24;
N, 3.83. Found: C, 69.31; H, 5.19; N, 3.89; MS: m/z (%) =
365 (34); 1H NMR (500 MHz, CDCl3): d = 3.76, 3.86, 3.88
(9 H, 3 × s, 3 × OCH3), 6.98 and 7.30 (4 H, 2 × d, J = 9.0 Hz,
ArH), 7.10 (1 H, s, CH of pyrrole), 7.28–7.45 (5 H, C6H5);
13C NMR (125.8 MHz, CDCl3): d = 52.3, 55.9 and 56.2 (3 ×
OCH3), 114.4, 121.9, 123.8, 125.0, 126.7, 127.5, 127.8,
128.1, 129.9, 132.8, 133.7 and 159.9 (aromatic and olefinic
carbons), 160.9 and 167.2 (2 × CO ester). 7b: Viscose oil; IR
Synlett 2009, No. 12, 1929–1932 © Thieme Stuttgart · New York

1932
M. Anary-Abbasinejad et al.
LETTER
(KBr): 1740, 1707 (ester) cm–1; Anal. Calcd for C21H19NO4:
C, 72.19; H, 5.48; N, 4.01. Found: C, 72.40; H, 5.29; N, 4.09;
MS: m/z (%) = 349 (19); 1H NMR (500 MHz, CDCl3): d =
2.42, 3.73, 3.85 (9 H, 3 × s, 3 × CH3), 6.64 and 7.10 (4 H,
2 × d, J = 8.4 Hz, C6H4CH3), 6.99 (1 H, s, CH of pyrrole),
7.23–7.59 (5 H, m, C6H5); 13C NMR (125.8 MHz, CDCl3):
d = 20.7, 52.4 and 52.8 (3 × CH3), 121.9, 123.7, 125.1, 126.3,
126.4, 127.6, 128.1, 129.0, 130.0, 133.0, 133.6, 137.4
(aromatic and olefinic carbons), 160.9, 167.2 (2 × CO ester).
7c: Viscose oil; IR (neat): 1712, 1743 (ester) cm–1; Anal.
Calcd for C21H18BrNO5: C, 56.77; H, 4.08; N, 3.15. Found:
C, 56.90; H, 4.22; N, 3.39; MS: m/z (%) = 443 (24); 1H NMR
(500 MHz, CDCl3): d = 3.77, 3.83, 3.81 (9 H, 3 × s, 3 ×
OCH3), 6.99 and 7.29 (4 H, 2 × d, J = 9.1 Hz, ArH), 7.15
(1 H, s, CH of pyrrole), 7.47 and 7.63 (4 H, 2 × d, J = 8.3 Hz,
ArH); 13C NMR (125.8 MHz, CDCl3): d = 52.3, 56.1 and
56.4 (3 × OCH3), 113.1, 121.9, 123.8, 125.7, 126.7, 127.8,
130.2, 131.0, 131.7, 132.8, 133.6, 159.2 (aromatic and
olefinic carbons), 160.8, 167.2 (2 × CO ester).
Synlett 2009, No. 12, 1929–1932 © Thieme Stuttgart · New York

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