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N-Carbonylureas from Azomethines and N-Chlorocarbonyl Isocyanate.

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(750 ml), and triethylamine (25 g, 0.25 mol) is added dropwise over 30 min. The temperature is kept at 25-30°C by
cooling in ice. After 1.5h the precipitate is filtered off,
affording (31 (160 g, 70%) as golden-red crystals, which
after recrystallization from dimethylformamide melt at
253 "C with decomposition.
chloride o r phosgene into the corresponding isocyanates,
the analogous reaction with ureas has not previously been
recorded. We have now prepared isocyanates of type ( 3 )
(water-clear distillable liquids) by a simple method, namely
addition of N-chlorocarbonyl isocyanate [2)[41to Schiff
bases ( I ) .
4-Cyano-7,8-dimethyl-2-o.xo-I,2,4-oxadiaiolo[2,3-a]quinoxaline 5-oxide (4):
( 3 ) (230 g, 1 mol) is suspended in chlorobenzene (2 I), and
a vigorous stream of phosgene is passed through the suspension a t 8 G 9 O o C , whereupon the color changes from
red to yellow. The reaction is complete when addition of
a sample of the yellow precipitate to water no longer produces a red color. On filtration, yellow crystals of (4)
(239 g, 93%) are obtained, which after recrystallization
from DMSO melt at 228°C with decomposition.
SJO-dioxide (5) :
( 4 ) (25.6 g, 0.1 mol) is suspended in dimethylfomamide
(1 50 ml) and treated with concentrated ammonia solution
(20 g). After 8 h, filtration affords yellowish-brown crystals
of (5) (25 g, 92%), which after recrystallization from dimethylformamide melt at 360°C with decomposition.
7&Dimethylbenzopteridine 5,IO-dioxide ( 6 ) :
( 5 ) (27.3 g, 0.1 mol) is stirred in 20% sulfuric acid (300 ml)
for 8 h at 80°C. Filtration then affords yellow crystals of
(6) (21.5 g, 77%).
7,8-Dimethylbenzopteridine( 7 ) . lumiclzrome
(6) (27.4 g, 0.1 mol) is suspended in methanol (200 ml) and
treated at 70°C dropwise with a solution of sodium dithionite (60 g) in water (210 ml). After 5 h the mixture is
cooled and filtered. The precipitate isolated is stirred with
water, thus affording lumichrome ( 7 ) as yellow crystals
that, after recrystallization from glacial acetic acid, melt
with decomposition at 354°C (Ref. [3], 360°C).
Received: May 23. 1972 [Z 680c IE]
German version : Angew. Chem. 84,1061 (1972)
Publication delayed a t authors' request
[ l ] K. Lev. F Seng. R. Nast. U . Eholzer., and R. Schubarr, Angew.
Chem. R I . 569 (1969); Angew. Chern. internat. Edit. 8, 596 (1969).
[Z] F . Seng, R. Nast, and K. Ley, Ger. Pat. Appl. P 16-70-743,O
(Aug. 26. 1966); DOS 1670743.
131 R. Kuhn, Chem. Ber. 67. 1826 (1934).
141 F. B. Mallor?... S L. Manor!. and C S. Wood. J. Amer. Chem.
SOC.87. 5433 (1965).
c1 c=o
( 21
( 1)
B p YCjtorr3
In ( 3 ) the basic character of the amide nitrogen is weakened
by the neighboring chlorine atom, which would be expected to contribute significantly t o the stability of such
N-carbonylureas. The reactivity towards acylatable compounds is comparable with that of alkoxycarbonyl isocyanates['I.
The structures of the compounds obtained are proved by
their IR spectra [stretchingvibrations at 1700cm-' (C=O)
and 2242 cm-I (N=C=O)], NMR spectra, results of
elemental analysis, and chemical reactions.
N-Chlorocarbonyl isocyanate (2) (105.5 g, 1 mol) in
chlorobenzene (250 ml) is treated dropwise over 45 min at
IS-30°C with the Schiff base (119 g, 1 mol) from benzaldehyde and methylamine. The whole is stirred at cu. 25 "C
for 3 h, then the chlorobenzene is removed at water-pump
pressure and the residue is distilled at oil-pump vacuum.
This affords (3a) (148 g, 66%) as a colorless oil of b.p.
112"C/0.05 torr.
Received: May 23. 1972 [Z 680d IE]
German version: A R ~ ~Chem.
w . 84,1062 (197-7)
Publication delayed a t authors' request
[I] A . J . Speziale and L. R. Smith, J . Org. Chem. 27, 3742 (1962).
[2] A. 1. Speziaie, L. R. Smith, and J . E. Fedder, J . Org. Chem 30.
4306 (1965); W . Kleberr and E. Miiller. DOS 1518 806 (Aug. 21. 1969).
Farbenfabriken Bayer AG.
131 L. J . Samaraj. N A . Bondor. and G.J. Derkarsch, Angew. Chem. 7'9.
897 (1967), Angew. Chem. internat. Edit. 6. 864 (1967)
141 H. Hagemann, Angew. Chem. 83, 906 (1971); Angew. Chem.
internat. Edit. 10. 832 (1971).
Cyclization of Azomethines by
N-Chlorocarbonsl Isocyanate
N-Carbonylureas from Azomethines and
N-ChIorocarbonyl Isocyanate
By Hermann Hagernann and Kurt Ley"'
By Hermunn Hagemann and Kurt Ley"]
Dedicated to Professor Otto Buyer on the occasion of his
70th birthday
Although it is known that carboxamides"', carbamidic
esters[*', and carbamidamide~[~I
are converted by oxalyl
Schiff bases from aromatic aldehydes add N-chlorocarbonyl isocyanate[" with retention of the isocyanate
group[']. The products, of type (Z), are formed also on
treatment of azomethines ( I ) with N-chlorocarbonyl
[*] Dr. H . Hagemann and Prof. Dr. K . Ley
Wissenschaftliches Hauptlaboratorium der Farbenfabriken
Bayer AG
509 Leverkusen-Bayerwerk (Germany)
[*I Dr. H. Hagemann and Prof. Dr. K . Ley
Wissenschaftliches Hauptlaboratorium der Farbenfabriken
Bayer A G
509 Leverkusen (Germany)
Dedicated to Professor Otto Bayer on the occasion of his
70th birthday
Afigen'. Chem. internor. Edit.
1 Vol. I 1 (1972) No. 11
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isocyanates, chlorocarbonyl, carbonylureas, azomethine
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