Synthesis of a new heterocyclic system-pyrrolo[1,2-a][4,1]benzoxazepine [3]

Full text of DOI:10.1023/A:1025170821406

Chemistry of Heterocyclic Compounds, Vol. 39, No. 5, 2003
SYNTHESIS OF A NEW HETEROCYCLIC SYSTEM –
PYRROLO[1,2-a][4,1]BENZOXAZEPINE
N. S. Kistanova, I. V. Mashevskaya, K. S. Bozdyreva, and A. N. Maslivets
Keywords: o-aminobenzyl alcohol, 3-aroyl-2,4-dihydro-1H-pyrrolo[1,2-a][4,1]benzoxazepine-1,2,4-
triones, aroylpyruvic acids, oxalyl chloride, pyrrolo[1,2-a]benzoxazepine, 2-phenacylidene-1,2,3,5-
tetrahydro-4,1-benzoxazepin-3-ones.
Heterocyclic enamino ketones react with oxalyl chloride to give hetereno[a]2,3-dihydro-2,3-
pyrrolediones [1-5] or 4-heteryl-2,3-dihydro-2,3-furandiones [6]. In order to expand the data base permitting us
to predict realization of one of the two pathways indicated above, we synthesized 2-phenacylidene-1,2,3,5-
tetrahydro-4,1-benzoxazepin-3-ones (1a-c) and studied the reaction of these compounds with oxalyl chloride.
The structure of substituted benzoxazepines 1a-c is the limiting structure for realization of one of the alternative
pathways of the reaction of these compounds with oxalyl chloride.
Substituted benzoxazepinones 1a-c were obtained in the reaction of aroylpyruvic acids with
o-aminobenzyl alcohol by a modification of our previous method [7]. The reaction of 1a-c with oxalyl chloride
under conditions used commonly for the synthesis of five-membered 2,3-dioxo heterocycles [1-6] gives 3-aroyl-
2
,4-dihydro-1H-pyrrolo[1,2-a][4,1]benzoxazepine-1,2,4-triones 3a-c instead of the expected 2-(2-aryl-4,5-
dioxo-4,5-dihydro-3-furyl)-3,5-dihydro-4,1-benzoxazepin-3-ones 2a-c.
ArCOCH COCOOH
2
O
O
NH2
O
N
∆
CH OH
2
Ar
O
O
2
a–c
O
O
(
COCl)2
O
O
N
N
H
COAr
O
O
a–c
Ar
1
a–c
3
O
1
-3 a Ar = Ph, b Ar = p-BrC
6
H
4
, c Ar = p-MeC
6
H
4
Closure of a pyrroledione ring probably occurs in this reaction due to its greater thermodynamic
stability relative to the alternative furandione ring, while steric hindrance leading to closure of a furandione ring
is not as significant as in our previous work [6]. This reaction is the first case reported for the construction of a
new heterocyclic system of substituted pyrrolo[1,2-a][4,1]benzoxazepine.
_
________________________________________________________________________________________
Perm State University, 614990 Perm, Russia; e-mail: koh2@psu.ru. Translated from Khimiya
Geterotsiklicheskikh Soedinenii, No. 5, pp. 773-775, May, 2003. Original article submitted March 20, 2003.
0
009-3122/03/3905-0673$25.00©2003 Plenum Publishing Corporation
673

1
The IR spectra were obtained in vaseline oil. The H NMR spectra were obtained in DMSO-d
6
at
4
00 MHz with HMDS as the internal standard.
Benzoyl-2,4-dihydro-1H-pyrrolo[1,2-a][4,1]benzoxazepine-1,2,4-trione (3a).
A
solution of
Z-2-phenacylidene-1,2,3,5-tetrahydro-4,1-benzoxazepin-3-one (1a) (0.01 mmol) and oxalyl chloride
(
0.01 mmol) in absolute benzene (3 ml) was heated at reflux for 50 min and then cooled. The precipitate formed
-1
was filtered off. Yield of compound 3a 3.00 g (90%); mp 213-215°C (dec., benzene). IR spectrum, ν, cm : 1775
1
(
C
(1)=O), 1752 (C(4)=O), 1717 (C(2)=O), 1651 (COC
6
H
5
). H NMR spectrum (400 MHz), δ, ppm, (J, Hz): 5.37,
5
.96 (2H, J = 12.8, AB system, CH
2
); 7.44-7.99 (9H, m, C
6
H
5
+ C
6
4
H ). Found, %: C 68.52; H 3.41; N 4.66.
C
19
H
5
11NO . Calculated, %: C 68.47; H 3.33; N 4.20.
3
-p-Bromobenzoyl-2,4-dihydro-1H-pyrrolo[1,2-a][4,1]benzoxazepine-1,2,4-trione (3b) was obtained
-1
analogously. Yield of compound 3b 3.79 g (92%); mp 199-201°C (dec., benzene). IR spectrum, δ, cm : 1776
1
(
C
(1)=O), 1746 (C(4)=O), 1723 (C(2)=O), 1640 (COC
6
H
4
). H NMR spectrum (400 MHz), δ, ppm, (J, Hz): 5.37,
5
.94 (2H, J = 12.6, AB system CH
2
); 7.37-7.91 (8H, m, 2C
6
H ). Found, %: C 55.40; H 2.39; Br 19.33; N 3.36.
4
C
19
H
10BrNO
5
. Calculated, %: C 55.36; H 2.45; Br 19.38; N 3.40.
3
-p-Methylbenzoyl-2,4-dihydro-1H-pyrrolo[1,2-a][4,1]benzoxazepine-1,2,4-trione (3c) was obtained
-1
analogously. Yield of compound 3c 2.81 g (81%); mp 203-205°C (dec., benzene). IR spectrum, δ, cm : 1785
1
(
(
C
(1)=O), 1745 (C(4)=O), 1735 (C(2)=O), 1640 (COC
6
H
4
). H NMR spectrum (400 MHz), δ, ppm, (J, Hz): 2.45
3H, s, CH
3
); 5.23, 5.96 (2H, dd, J = 12.6, AB system CH
2
); 7.16-7.88 (8H, m, 2C
6
4
H ). Found, %: C 69.12;
H 3.78; N 4.06. C20
H13NO
5
. Calculated, %: C 69.16; H 3.77; N 4.03.
This work was carried out with the financial support of the Russian Basic Research Fund (Grants
No. 01-03-32641 and 02-03-96411). The NMR spectra were taken at the Urals NMR Center (Russian Basic
Research Fund Grant No. 00-03-40139).
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