ISSN 1070-4280, Russian Journal of Organic Chemistry, 2009, Vol. 45, No. 6, pp. 946–947. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © V.V. Khalturina, S.N. Shurov, A.N. Maslivets, 2009, published in Zhurnal Organicheskoi Khimii, 2009, Vol. 45, No. 6, pp. 958–959.
SHORT
COMMUNICATIONS
Mild Acylation of Fischer Indole
with 5-Aryl-2,3-dihydrofuran-2,3-diones
V. V. Khalturinaa, S. N. Shurovb, and A. N. Maslivetsb
a Institute of Technical Chemistry, Ural Division, Russian Academy of Sciences, ul. Lenina 3, Perm, 614013 Russia
b Perm State University, ul. Bukireva 15, Perm, 614990 Russia
e-mail: koh2@psu.ru
Received July 4, 2008
DOI: 10.1134/S107042800906027X
Reactions of 2,3-dihydrofuran-2,3-diones with sec-
ondary heterocyclic enamines were not studied previ-
ously. We examined reactions of 5-aryl-2,3-furan-2,3-
diones Ia and Ib with 1,3,3-trimethyl-2-methylidene-
2,3-dihydro-1H-indole (II, Fischer indole) at a molar
ratio of 1:1 on heating in boiling anhydrous benzene
(reaction time 1–2 min, until bright yellow color typ-
ical of initial furandiones I disappeared) and obtained
in good yields (2Z)-1-aryl-3-hydroxy-5-(1,3,3-trimeth-
yl-2,3-dihydro-1H-indol-2-ylidene)pent-2-ene-1,4-di-
ones IIIa and IIIb. The spectral parameters of com-
pounds IIIa and IIIb indicated that they exist in
DMSO-d6 solution as mixtures of enol and diketone
tautomers A and B at a ratio of ~5:1. Their spectra
were similar to those of model (2Z,5Z)-3-hydroxy-5-
{8,8-dimethyl-2,3,8,9-tetrahydro[1,4]dioxino[2,3-g]-
isoquinolin-6(7H)-ylidene}-1-phenylpent-2-ene-1,4-
dione whose structure was confirmed by the X-ray dif-
fraction data.
(2Z)-3-Hydroxy-5-(1,3,3-trimethyl-2,3-dihydro-
1H-indol-2-ylidene)-1-phenylpent-2-ene-1,4-dione
(IIIa). A solution of 3.0 mmol of 5-phenyl-2,3-dihy-
drofuran-2,3-dione (Ia) and 3.0 mmol of Fischer
indole II in 20 ml of anhydrous benzene was heated
for 1 min under reflux. The mixture was cooled, and
the precipitate was filtered off. Yield 89%, mp 157–
159°C (decomp.; from ethanol). IR spectrum, ν, cm–1:
3170 br (OH, assoc.), 1608 br (C=O, assoc.). 1H NMR
spectrum, δ, ppm: A: 1.74 s (6H, Me), 3.38 s (3H, Me),
6.18 s (1H, 5-H), 7.13 s (1H, 2-H), 7.08–8.09 m (9H,
Harom), 16.08 br.s (1H, OH); B: 1.65 s (6H, Me), 3.35 s
(3H, Me), 4.48 s (2H, 2-H), 5.96 s (1H, 5-H), 7.06–
7.99 m (9H, Harom). Found, %: C 75.91; H 6.21;
N 3.84. C22H21NO3. Calculated, %: C 76.06; H 6.09;
N 4.03.
(2Z)-3-Hydroxy-1-(4-methylphenyl)-5-(1,3,3-tri-
methyl-2,3-dihydro-1H-indol-2-ylidene)pent-2-ene-
1,4-dione (IIIb) was synthesized in a similar way.
Yield 87%, mp 170–172°C (decomp.; from ethanol).
IR spectrum, ν, cm–1: 3160 br (OH, assoc.), 1608 br
Presumably, the described transformation involves
acylation of the exocyclic methylene group in indole II
by the carbonyl group in position 2 of 5-aryl-2,3-di-
hydrofuran-2,3-dione Ia or Ib, followed by opening of
the furan ring at the O1–C2 bond, as was reported for
the reaction of 5-aryl-2,3-dihydrofuran-2,3-diones with
1-methyl-3,4-dihydroisoquinolines [1, 2].
1
(C=O, assoc.). H NMR spectrum, δ, ppm: A: 1.74 s
(6H, Me), 2.41 s (3H, MeC6H4), 3.37 s (3H, Me),
6.18 s (1H, 5-H), 7.09 s (1H, 2-H), 7.08–7.98 m (8H,
Harom), 16.15 br.s (1H, OH); B: 1.65 s (6H, Me), 2.39 s
(3H, MeC6H4), 3.34 s (3H, Me), 4.45 s (2H, 2-H),
Me
Me
Me
Me
Me
Me
O
H
Ar
Ar
O
+
CH2
N
N
N
O
Ar
O
·
O
·
·
O
O
H
O
Me
O
Me
Me
Ia, Ib
II
A
IIIa, IIIb
B
Ar = Ph (a), 4-MeC6H4 (b).
946
Khalturina
