Acylation of 2′,5′,5′-trimethyl-4′,5′- dihydro-4H-spiro-[naphthalene-1,3′-pyrrol]-4-one with 5-arylfuran-2,3- diones

Full text of DOI:10.1134/S1070428011070256

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2011, Vol. 47, No. 7, pp. 1119–1120. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © V.V. Konovalova, Yu.V. Shklyaev, A.N. Maslivets, 2011, published in Zhurnal Organicheskoi Khimii, 2011, Vol. 47, No. 7,
pp. 1099–1100.
SHORT
COMMUNICATIONS
Acylation of 2′,5′,5′-Trimethyl-4′,5′-dihydro-4H-spiro-
[naphthalene-1,3′-pyrrol]-4-one with 5-Arylfuran-2,3-diones
V. V. Konovalovaa, Yu. V. Shklyaeva, and A. N. Maslivetsb
a Institute of Technical Chemistry, Ural Division, Russian Academy of Sciences, Perm, Russia
b Perm State University, ul. Bukireva 15, Perm, 614990 Russia
e-mail: koh2@psu.ru
Received October 16, 2010
DOI: 10.1134/S1070428011070256
We previously showed that cyclic Schiff bases, e.g.,
3,3-dialkyl-1-methyl-3,4-dihydroisoquinolines (I),
readily react with unsaturated electrophiles such as iso-
cyanates [1], hexafluoroisopropylidenemalononitrile
[2], 3-nitro-2-trifluoromethylchromene [3], and 5-aryl-
furan-2,3-diones [4]. Although enamino tautomer of
compounds I was not detected by modern instrumental
methods, the above reactions unambiguously indicated
formation of that tautomer as reactive species at least
in solution. Spirocyclic 2-methyl-4,5-dihydro-1H-pyr-
roles, in particular 2′,5′,5′-trimethyl-4′,5′-dihydro-4H-
spiro[naphthalene-1,3′-pyrrol]-4-one (II), also exist in
the imino form [5]; enamino tautomer is possible for
derivatives containing an electron-acceptor substituent
on the β-carbon atom in the enamine fragment. Taking
into account structural similarity of compounds I and
II, we presumed that the latter are also capable of re-
acting with 5-arylfuran-2,3-diones, though in this case
steric hindrances should be more considerable than for
isoquinoline derivatives I.
In fact, 2′,5′,5′-trimethyl-4′,5′-dihydro-4H-spiro-
[naphthalene-1,3′-pyrrol]-4-one (II) reacted with
an equimolar amount of 5-arylfuran-2,3-dione IIIa or
IIIb on heating in anhydrous benzene over a period of
3–4 h (TLC monitoring) to give the corresponding
(2Z,5Z)-1-aryl-3-hydroxy-5-(5′,5′-dimethyl-4-oxo-
2′H,4H-spiro[naphthalene-1,3′-pyrrolidin]-2′-ylidene)-
pent-2-ene-1,4-diones IVa and IVb. The spectral
parameters of compounds IVa and IVb indicated that
they exist in DMSO-d6 as mixtures of keto enol and
O
O
O
+
Me
CH2
Ar
O
O
N
Me
NH
Me
Me
Me
II
IIIa, IIIb
O
O
H
·
·
O
O
·
O
O
N
N
Ar
Ar
O
O
·
·
Me
·
Me
·
·
·
H
H
Me
Me
A
IVa, IVb
B
Ar = Ph (a), 4-MeC6H4 (b).
1119

KONOVALOVA et al.
1120
diketone tautomers A and B at a ratio of ~5:1. Presum-
ably, the described reaction involves acylation of the
=CH2 carbon atom in the enamino tautomer of II by
the C2=O carbonyl group in furandione III, followed
by opening of the furan ring at the O1–C2 bond, as in
the reaction of 5-arylfuran-2,3-diones with 1-methyl-
3,4-dihydroisoquinolines [4].
Thus we can state that spirocyclic dihydropyrrole
derivatives like II also give rise to imine–enamine
tautomerism and that considerable steric hindrances
created by geminal methyl groups on C5 and spiro-
fused naphthalene fragment on C3 do not hamper reac-
tion of II with 5-arylfuran-2,3-diones.
3-H), 6.90 s (1H, 2″-H), 7.25 d (1H, 2-H), 7.49–8.04 m
(8H, Harom), 10.82 s (1H, NH), 16.10 br.s (1H, OH); B:
1.53 s and 1.58 s (3H each, Me), 2.39 s (3H, MeC6H4),
2.41 m (2H, 4′-H, AB system), 4.33 s (2H, 2″-H),
4.84 s (1H, 5″-H), 6.40 d (1H, 3-H), 7.21 d (1H, 2-H),
7.43–8.00 m (8H, Harom), 10.52 s (1H, NH). Found, %:
C 75.69; H 5.95; N 3.17. C27H25NO4. Calculated, %:
C 75.86; H 5.89; N 3.28.
The IR spectra were recorded on a UR-20 spec-
trometer from samples dispersed in mineral oil. The
1H NMR spectra were measured on a Varian Mercury
Plus 300 spectrometer (300 MHz) from solutions in
DMSO-d6 using tetramethylsilane as internal refer-
ence. The purity of the isolated compounds was check-
ed by TLC on Silufol plates using ethyl acetate as
eluent; spots were developed by treatment with a 0.5%
solution of tetrachloro-1,4-benzophenone in toluene.
(2Z,5Z)-3-Hydroxy-5-(5′,5′-dimethyl-4-oxo-
2′H,4H-spiro[naphthalene-1,3′-pyrrolidin]-2′-yli-
dene)-1-phenylpent-2-ene-1,4-dione (IVa). A solution
of 1.0 mmol of 5-phenylfuran-2,3-dione (IIIa) and
1.0 mmol of compound II in 20 ml of anhydrous ben-
zene was heated for 4 h under reflux. The mixture was
cooled, and the precipitate was filtered off. Yield 82%,
mp 194–195°C (decomp., from ethanol). IR spectrum,
ν, cm–1: 3150 br (OH, NH), 1660 (C4=O), 1595 br
This study was performed under financial support
by the Presidium of the Russian Academy of Sciences
(program no. 18), by the Russian Foundation for Basic
Research (project no. 08-03-01032), and by the Ural
Division of the Russian Academy of Sciences
(Scientific Special-Purpose Program “Competition of
Scientific Projects of Young Scientists and Post-
Graduate Students”).
1
(C=O). H NMR spectrum, δ, ppm: A: 1.59 s and
1.65 s (3H each, Me), 2.46 m (2H, 4′-H, AB system),
5.08 s (1H, 5″-H), 6.45 d (1H, 3-H), 6.92 s (1H, 2″-H),
7.26 d (1H, 2-H), 7.41–8.06 m (9H, Harom), 10.77 s
(1H, NH), 16.04 br.s (1H, OH); B: 1.53 s and 1.60 s
(3H each, Me), 2.41 m (2H, 4′-H, AB system), 4.31 s
(2H, 2″-H), 4.85 s (1H, 5″-H), 6.43 d (1H, 3-H), 7.22 d
(1H, 2-H), 7.37–8.05 m (9H, Harom), 10.57 s (1H, NH).
Found, %: C 75.46; H 5.63; N 3.24. C26H23NO4. Cal-
culated, %: C 75.53; H 5.61; N 3.39.
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 47 No. 7 2011