Synthesis of pyrrolo[1,2-a]pyrazine-1,6,7-triones from 3- methylidenepiperazin-2-ones and oxalyl chloride

Full text of DOI:10.1134/S1070428013060286

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2013, Vol. 49, No. 6, pp. 943–944. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © A.V. Chervyakov, A.N. Maslivets, 2013, published in Zhurnal Organicheskoi Khimii, 2013, Vol. 49, No. 6, pp. 956–957.
SHORT
COMMUNICATIONS
Synthesis of Pyrrolo[1,2-a]pyrazine-1,6,7-triones
from 3-Methylidenepiperazin-2-ones and Oxalyl Chloride
A. V. Chervyakov and A. N. Maslivets
Perm State National Research University, ul. Bukireva 15, Perm, 614990 Russia
e-mail: koh2@psu.ru
Received March 6, 2012
DOI: 10.1134/S1070428013060286
We previously reported on reactions of heterocyclic
enamino ketones with oxalyl chloride, which produced
hetareno[e]pyrrole-2,3-diones [1–4] or 4-hetarylfuran-
2,3-diones [4, 5]. With a view to accumulate more data
allowing a priori prediction of one or another path in
the above reaction to be made, we have synthesized
1-aryl-3-phenacylidenepiperazin-2-ones Ia and Ib and
examined their reaction with oxalyl chloride. The
structure of substituted piperazinones seems to be
intermediate from the viewpoint of their reaction with
oxalyl chloride along one of the two possible
pathways.
sponding 2-aryl-8-benzoyl-3,4-dihydropyrrolo[1,2-a]-
pyrazine-1,6,7(2H)-triones IIIa and IIIb. Presumably,
closure of fused dioxopyrrole ring is more thermody-
namically favorable than alternative formation of
furandione fragment. The observed reaction may be
regarded as a new synthetic route to functionalized
pyrrolo[1,2-a]pyrazine-1,6,7-trione derivatives.
8-Benzoyl-2-phenyl-3,4-dihydropyrrolo[1,2-a]-
pyrazine-1,6,7(2H)-trione (IIIa). A solution of 1.00 g
(3.4 mmol) of compound Ia in 15 ml of anhydrous
toluene was added in portions under stirring to a hot
solution of 0.44 ml (5.1 mmol) of oxalyl chloride in
15 ml of anhydrous toluene. The mixture was heated
for 2 h under reflux, and the red crystalline solid was
filtered off and dried under reduced pressure. Yield
50%, mp 149–151°C (from toluene). IR spectrum, ν,
cm–1: 1735 (C6=O, C7=O), 1665 (C1=O), 1645
(COPh). 1H NMR spectrum, δ, ppm: 4.03–4.13 m (4H,
CH2CH2), 7.16–7.66 m (8H, Harom), 7.86 d (2H, o-H in
PhCO, J = 7.4 Hz). Found, %: C 69.33; H 4.09;
Substituted piperazinones Ia and Ib were synthe-
sized by reaction of methyl 4-phenyl-2,4-dioxobuta-
noate with N-arylethane-1,2-diamines. Compounds Ia
and Ib were brought into reaction with oxalyl chloride
under the standard conditions for the synthesis of five-
membered dioxo heterocycles. However, instead of
expected 4-(4-aryl-3-oxo-3,4,5,6-tetrahydropyrazin-2-
yl)-5-phenylfuran-2,3-diones II, we isolated the corre-
O
O
O
O
Ar
N
Ph
N
O
O
(COCl)2
Ar
Ph
IIa, IIb
Ar
NH2
Ph
N
+
N
OMe
H
O
NH
O
O
Ph
O
O
Ia, Ib
Ar
N
O
N
O
IIIa, IIIb
Ar = Ph (a), 4-MeC6H4 (b).
943

CHERVYAKOV, MASLIVETS
944
N 8.00. C20H14N2O4. Calculated, %: C 69.36; H 4.07;
N 8.09.
checked by TLC on Silufol plates using ethyl acetate
as eluent; spots were visualized by treatment with
iodine vapor.
8-Benzoyl-2-(4-methylphenyl)-3,4-dihydropyr-
rolo[1,2-a]pyrazine-1,6,7(2H)-trione (IIIb). A solu-
tion of 1.00 g (3.3 mmol) of compound Ib in 30 ml of
anhydrous benzene was added in portions under stir-
ring to a hot solution of 0.42 ml (4.9 mmol) of oxalyl
chloride in 30 ml of anhydrous benzene. The mixture
was heated for 1 h under reflux and cooled, 40 ml of
anhydrous petroleum ether (bp 40–70°C) was added,
and the precipitate was filtered off and dried under
reduced pressure. Yield 65%, mp 147–150°C (from
benzene). IR spectrum, ν, cm–1: 1755 (C6=O), 1726
This study was performed under financial support
by the Ministry of Education and Science of the
Russian Federation, by the Ministry of Education of
Perm Krai (International Research Teams Competi-
tion), and by the Russian Foundation for Basic
Research (project nos. 12-03-31157, 12-03-00696).
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1
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