Two pathways in the cycloaddition of 4-nitrobenzaldehyde to acyl(imidoyl)ketene

Full text of DOI:10.1134/S1070428013070257

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2013, Vol. 49, No. 7, pp. 1092–1093. © Pleiades Publishing, Ltd., 2013.
Original Russian Text © V.A. Maslivets, A.N. Maslivets, 2013, published in Zhurnal Organicheskoi Khimii, 2013, Vol. 49, No. 7, pp. 1106–1107.
SHORT
COMMUNICATIONS
Two Pathways in the Cycloaddition of 4-Nitrobenzaldehyde
to Acyl(imidoyl)ketene
V. A. Maslivets and A. N. Maslivets
Perm State National Research University, ul. Bukireva 15, Perm, 614990 Russia
e-mail: koh2@psu.ru
Received March 20, 2012
DOI: 10.1134/S1070428013070257
Aroyl(benzoxazinyl)ketenes I generated by thermal
decarbonylation of 3-aroylpyrrolo[2,1-c][1,4]benzoxa-
zine-1,2,4-triones II undergo [4+2]-cyclodimerization
in the absence of other reaction partners. In this trans-
formation, one molecule I acts as dienophile via the
ketene C=C bond, and the other acts as diene through
the conjugated C=C–C=N bond sequence in the imid-
oylketene fragment [1]. Attempts to trap aroyl(benz-
oxazinyl)ketenes I with 4-bromobenzaldehyde or
Schiff base lead to the formation of the corresponding
[4 + 2]-cycloadducts with participation of the
C=C–C=N fragment in imidoylketene I and C=O bond
of 4-bromobenzaldehyde [2] or C=N bond of Schiff
base [3]. On the other hand, [4+2]-cycloaddition of
N,N′-dicyclohexylcarbodiimide to ketenes I involves
the C=C–C=O bond sequence of the aroylketene frag-
ment in I and the C=N bond of N,N′-dicyclohexyl-
carbodiimide [4]. According to the TLC data, all the
above reactions are regioselective.
of 15 min (until disappearance of violet color typical
of initial compound II) we obtained a mixture of
4-benzoyl-1-(4-nitrophenyl)-1,3-dihydro-5H-[1,3]oxa-
zino[4,3-c][1,4]benzoxazine-3,5-dione (III) and
3-[2-(4-nitrophenyl)-4-oxo-6-phenyl-4H-1,3-dioxin-5-
yl]-2H-1,4-benzoxazin-2-one (IV) at a ratio of ~5:3.
The spectral parameters of compounds III and IV
were fairly similar to those of structurally related
1-(4-bromophenyl)-4-(4-methylphenyl)-1,3-dihydro-
5H-[1,3]oxazino[4,3-c][1,4]benzoxazine-3,5-dione (V)
[2] and 2-(3-cyclohexyl-2-cyclohexylimino-4-oxo-6-
phenyl-3,4-dihydro-2H-1,3-oxazin-5-yl]-3-phenylquin-
oxaline (VI) [5] whose structure was unambiguously
determined by X-ray analysis. Obviously, compounds
III and IV are formed as a result of thermal decar-
bonylation of 3-benzoylpyrrolo[2,1-c][1,4]benzoxa-
zine-1,2,4-trione (II) with generation of benzoyl(benz-
oxazinyl)ketene I which reacted with 4-nitrobenzal-
dehyde according to the [4+2]-cycloaddition pattern
involving the aldehyde C=O bond and both C=C–C=O
and C=C–C=N conjugated bond systems in aroyl-
(imidoyl)ketene I.
By heating a solution of 3-benzoylpyrrolo[2,1-c]-
[1,4]benzoxazine-1,2,4-trione (II) and 4-nitrobenzal-
dehyde in pseudocumene at 168–169°C over a period
O
O
O
O
O
O
Δ
COPh
N
N
Ph
–CO
·
O
O
II
I
O
N
O
O
O
O
O
Ph
4-O2NC6H4CHO
Ph
N
O
+
4-O2NC6H4
O
O
O
C6H4NO2-4
III
IV
1092

TWO PATHWAYS IN THE CYCLOADDITION OF 4-NITROBENZALDEHYDE
1093
O
O
N
Ph
O
Ph
N
C6H4Me-4
N
O
C6H4Br-4
O
O
O
N
NCy
Cy
V
VI
Thus the described reaction is an example of two
concurrent [4+2]-cycloaddition pathways in reactions
of ambident dienes [acyl(imidoyl)ketenes I in which
the imidoyl fragment is a part of a heterocyclic
system], and it may be regarded as a new method of
synthesis of difficultly accessible polyfunctionalized
oxazinylbenzoxazinones.
6″-H, J = 8.7 Hz). Found, %: C 65.52; H 3.17; N 6.33.
C24H14N2O7. Calculated, %: C 65.16; H 3.19; N 6.33.
The IR spectra were recorded on a Perkin Elmer
Spectrum Two spectrometer from samples dispersed in
1
mineral oil. The H NMR spectra were measured on
a Bruker AM-400 instrument at 400 MHz from solu-
tions in DMSO-d6 using tetramethylsilane as internal
reference. The purity of the isolated compounds was
checked by TLC on Silufol plates using benzene–ethyl
acetate (5:1) and ethyl acetate as eluents.
4-Benzoyl-1-(4-nitrophenyl)-1,3-dihydro-5H-
[1,3]oxazino[4,3-c][1,4]benzoxazine-3,5-dione (III)
and 3-[2-(4-nitrophenyl)-4-oxo-6-phenyl-4H-1,3-di-
oxin-5-yl]-2H-1,4-benzoxazin-2-one (IV). A solution
of 3.0 mmol of compound II and 3.0 mmol of 4-nitro-
benzaldehyde in 10 ml of anhydrous pseudocumene
was heated for 15 min under reflux. The mixture was
cooled, and the yellow precipitate (compound III) was
filtered off. Yield 50%, mp 227–228°C (decomp., from
toluene). IR spectrum, ν, cm–1: 1770 (C5=O), 1716
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 no. 12-03-00696).
1
(C3=O), 1675 (COPh). H NMR spectrum, δ, ppm:
REFERENCES
7.26–7.65 m (9H, Ph, 7-H, 8-H, 9-H, 10-H), 7.87 d
(2H, 3′-H, 5′-H, J = 8.7 Hz), 8.23 s (1H, 1-H), 8.33 d
(2H, 2′-H, 6′-H, J = 8.7 Hz). Found, %: C 65.56;
H 3.22; N 6.29. C24H14N2O7. Calculated, %: C 65.16;
H 3.19; N 6.33.
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Petroleum ether (bp 40–70°C), 2 ml, was added to
the mother liquor, the precipitate was filtered off, the
filtrate was kept for 2 days, and the colorless precip-
itate was filtered off. Yield of IV 30%, mp 183–184°C
(decomp., from benzene). IR spectrum: ν 1737 cm–1
(C2=O, C4′=O). 1H NMR spectrum, δ, ppm: 7.41 s (1H,
2′-H), 7.44–7.80 m (9H, Ph, 5-H, 6-H, 7-H, 8-H),
8.09 d (2H, 3″-H, 5″-H, J = 8.7 Hz), 8.42 d (2H, 2″-H,
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 49 No. 7 2013