Chemistry Reference
In-Depth Information
Ethoxalyl isocyanate 489 was obtained from oxalamic acid ethyl ester 488 [347] with
oxalyl chloride.
O
O
(COCl)
2
O
O
3
3
H
2
N
OCN
O
O
488
489
Phosphoramidic or thiophosphoramidic acid dialkyl esters (Et, iPr) react with
oxalyl dichloride to give the corresponding isocyanates [348, 349] under mild con-
ditions, i.e. 1 h, 50
C in tetrachloromethane; 64% yield [350].
O
O
(COCl)
2
ZR
OR
ZR
OR
P
P
H
2
N
carbon tetrachloride
OCN
R =
i
-Pr, Et
Z = O, S
490
491
Typical procedure. Diethoxyphosphinyl isocyanate (diethyl phosphorocyanatidate)
[350]:
A solution of diethyl phosphoramidate (30.6 g, 0.2 mol) in tetrachloro-
methane (50 mL) was slowly added dropwise with stirring and e
cient external
cooling to a solution of oxalyl chloride (27.9 g, 0.22 mol) in the same solvent (150
mL). The reaction temperature was kept at
5to0
C. After completion of the
addition, the temperature of the mixture was slowly increased to 50
C and this
was maintained for 1 h. The mixture was then cooled to room temperature, fil-
tered, and concentrated in vacuo. The residual liquid product was distilled in vacuo
(bp 85-87
C/10 Torr); yield 22.9 g (64%).
Similar transformations have been reported for the preparation of amidothio-
phosphoric acid O,O
0
-dialkyl ester isocyanates 492 [348, 349] and O-alkyl-N-dialkyl-
phosphorothioate diamide 493 [351].
S
S
R
2
R
1
R
2
R
1
OO
P
ON
P
R
3
NCO
NCO
492
493
R
1
= Et R
2
= Bu R
3
= Bu
R
1
= Pr R
2
= Et R
3
= Et
R
1
= Et R
2
= Pr R
3
= Pr
R
1
= Et R
2
= Et R
3
= Et
R
1
= Pr R
2
= Pr
R
1
= Et R
2
= Et
R
1
= Bu R
2
= Bu
R
1
= Me R
2
= Et
Methanesulfonyl isocyanate 495 was prepared from methanesulfonamide 494 with
oxalyl dichloride [352].
