Chemistry Reference
In-Depth Information
Tab. 4.10.
Fluoro- and chlorophenyl iso-
cyanates 271 prepared with triphosgene [179].
Substituent X
in 271
Yield (%)
3-F
29
2-F
32
3-CF
3
42
4-Cl
36
3-Cl
69
2-Cl
54
4-F
38
NH
2
NCO
(CCl
3
O)
2
CO
R
1
R
1
Dioxane, 100°C
R
2
R
2
269
270
Fluoro- and chloro-substituted phenyl isocyanates 271 have been prepared by heating
the anilines with triphosgene and triethylamine either in benzene [179] (Table
4.10) or in dichloromethane [181].
NCO
X
271
Ureas from dl-a-methyltryptophan were obtained by coupling the amino group
with 4-chlorophenyl isocyanate, 2-naphthyl isocyanate 273,ortriphenylmethyl iso-
cyanate 275, the latter two intermediates being prepared from the corresponding
amines and triphosgene [182].
NH
2
NCO
(CCl
3
O)
2
CO
PhNO
2
or toluene,
0°C
272
273
Ph
Ph
(CCl
3
O)
2
CO
NCO
NH
2
Ph
Ph
Ph
Ph
CH
2
Cl
2,
0°C
274
275
Typical procedure. Triphenylmethyl isocyanate 275 [182]:
To a solution of triphosgene
(1.10 g, 3.70 mmol) in dry dichloromethane (15 mL) was added a solution of tri-
