Recyclization of Acylation Products of 2-Aryl-5-hydrazino-4-(dialkoxyphosphoryl)oxazoles

Full text of DOI:10.1023/A:1013935601475

Russian Journal of General Chemistry, Vol. 71, No. 11, 2001, pp. 1825 1826. Translated from Zhurnal Obshchei Khimii, Vol. 71, No. 11, 2001,
pp. 1930 1931.
Original Russian Text Copyright
2001 by Brovarets, Pil’o, Popovich, Vydzhak, Drach.
LETTERS
TO THE EDITOR
Recyclization of Acylation Products
of 2-Aryl-5-hydrazino-4-(dialkoxyphosphoryl)oxazoles
V. S. Brovarets, S. G. Pil’o, T. P. Popovich, R. N. Vydzhak, and B. S. Drach
Institute of Bioorganic and Petroleum Chemistry, National Academy of Sciences of Ukraine, Kiev, Ukraine
Received November 16, 2000
We found recently that phosphorus-containing en-
amides of the general formula
4-phosphorylated derivatives of 2-alkyl(aryl)-5-hydra-
zinooxazoles I [1]. Here we report that compounds
I can be converted by easy reactions (see scheme)
to 2,5-disubstituted 1,3,4-oxadiazoles containing the
Cl2C=C(NHCOR)P(O)(OAlk)2
readily react with excess hydrazine hydrate to give CH(NHCOR)P(O)(OAlk)2 group in the side chain.
P(O)(OCH3)2
H
P(O)(OCH3)2
H
P(O)(OCH3)2
RCOCl,
Et3N
N
N
N
Ar
Ar
Ar
N
N
N
O
O
O
NH2
NH
NH
O
O
R
R
Ia, Ib
IIa, IIb
IIIa, IIIb
EtOH, H2O,
H
N
H
N
P(O)(OCH3)2
H
P(O)(OCH3)2
P(O)(OCH3)2
H
N
or
Ar
Ar
Ar
N
N
N
H2O or
EtOH
EtO
O
O O
O
O
NH
NH
N
O
O
R
R
R
IVa, IVb
Va, Vb
VIa, VIb
Ar = C6H5, R = 4-CH3C6H4 (a); Ar = 4-ClC6H4, R = 4-CH3C6H4 (b).
Probably, the reacting species in recyclization are
not the aromatic oxazole derivatives II but their pro-
totropic tautomers III containing the 2-oxazoline ring,
because this ring can be cleaved under mild conditions
with water or ethanol to form intermediates IV or
V capable of intramolecular cyclocondensation. The
For example, in the 1H NMR spectra of compounds
VIa and VIb the doublet of doublets at 6.25
6.35 ppm can be assigned to the methine proton
|
of the NH CH P(O)< group. Also, the 13C NMR
spectrum of VIb contains two downfield signals
( > 164 ppm) of the C2 and C5 atoms of the electron-
deficient 1,3,4-oxadiazole ring. The other evidences of
structure VI and possible applications of the new re-
cyclization will be discussed in subsequent papers.
transformation IV
VI resembles the cyclization of
many other N,N -diacyl derivatives of hydrazine [2].
1
The IR and H and 13C NMR data are consistent
with the structure of the final products of recycliza-
4-Dimethoxyphosphoryl-5-(2-p-toluylhydrazino)-
2-phenyloxazole IIa. To a solution of 4 mmol of Ia
tion II
VI.
1070-3632/01/7111-1825$25.00 2001 MAIK Nauka/Interperiodica

1826
BROVARETS et al.
[1] in 10 ml of acetonitrile we added 4.4 mmol of tri-
ethylamine and 4 mmol of p-toluyl chloride. The re-
sulting mixture was left for 24 h at 20 25 C, and the
precipitate was filtered off, washed with water, com-
bined with the product obtained from filtrate, and used
for subsequent syntheses without additional purifica-
tion. Yield 80%, mp 165 166 C. Found, %: N 10.35;
P 7.60. C19H20N3O5P. Calculated, %: N 10.47; P 7.72.
2-[Dimethoxyphosphoryl(p-chlorobenzoylami-
no)]methyl-5-p-tolyl-1,3,4-oxadiazole VIb was pre-
pared under the same conditions as VIa. Yield 86%,
1
mp 150 151 C. H NMR spectrum, , ppm: 2.40 s
(3H, CH3), 3.82 m (6H, 2CH3O), 6.27 d.d (1H,
3
2
NCHP, JHH 8.6 Hz, JHP 21.4 Hz), 7.40 8.00 m
(8H, 2C6H4), 9.68 br.s (1H, NH). 13C NMR spectrum,
C, ppm: 21.11 (CH3), 43.79 (CH), 53.90, 54.19
(2CH3O), 120.17, 131.61, 136.85, 142.49 (Ci, p, Ph),
126.55, 128.44, 129.88, 130.03 (Co, m, Ph), 161.05
(C=O), 164.82, 165.60 (C2=N, C5=N). Found, %: Cl
8.05; N 9.72; P 7.02. C19H19ClN3O5P. Calculated, %:
Cl 8.14; N 9.64; P 7.11.
4-Dimethoxyphosphoryl-5-(2-p-toluylhydrazino)-
2-p-chlorophenyloxazole IIb was prepared similarly.
1
Yield 83%, mp 170 171 C. H NMR spectrum,
,
3
ppm: 2.38 s (3H, CH3), 3.67 d (6H, 2CH3O, JHP
12.0 Hz), 7.30 7.80 m (8H, 2C6H4), 8.77 br.s (1H,
NH), 10.75 br.s (1H, NHCO). Found, %: Cl 8.05; P
6.99. C19H19ClN3O5P. Calculated, %: Cl 8.14; P 7.11.
1
The H and 13C NMR spectra were recorded on
a Varian VXR-300 spectrometer in DMSO-d6 relative
to TMS.
2-[Dimethoxyphosphoryl(benzoylamino)]methyl-
5-p-tolyl-1,3,4-oxadiazole VIa. A solution of 1 mmol
of IIa in 10 ml of 80% aqueous ethanol was refluxed
for 0.5 h, and the precipitate was filtered off and re-
crystallized from aqueous ethanol. Yield 80%, mp 132
REFERENCES
1. Brovarets, V.S., Vydzhak, R.N., Pil’o, S.G., Zyuz’, K.V.,
and Drach, B.S., Zh. Obshch. Khim., 2001, vol. 71,
no. 11, pp. 1822 1824.
1
133 C. H NMR spectrum, , ppm: 2.40 s (3H, CH3),
3
3.82 m (6H, 2CH3O), 6.35 d.d (1H, NCHP, JHH
2
8.6 Hz, JHP 21.4 Hz), 7.20 8.00 (9H, C6H4, C6H5),
2. The Chemistry of Heterocyclic Compounds, vol. 17:
Five- and Six-Membered Compounds with Nitrogen and
Oxygen, Weissberger, A. and Wiley, R.H., Eds., New
York: Wiley, 1962, pp. 263 282.
3
9.71 d (1H, NH, JHH 8.6 Hz). Found, %: C 56.55; H
4.95; N 10.30; P 7.62. C19H20N3O5P. Calculated, %:
C 56.86; H 5.02; N 10.47; P 7.72.
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 71 No. 11 2001