Chemistry Reference
In-Depth Information
R
N
O
1. CS
2
, Et
3
N
2. MeI
ZnCl
2
, MeCN
H
2
O
RNH
2
MeS
SMe
RHN
SMe
1080
1081
O
R'R"NH
RHN
NR'R"
(60-89 %)
1082
Ph
R = alkyl,
MeO
O
Ph
R' = H, alkyl
R" = alkyl, cycloalkyl, aryl,
MeO
O
SiI
2
H
2
, iPr
2
NEt
O
O
R
1
NH
2
1084
R
1
R
R'
R
RNCO
H
O
H
H
D
1083
1085
4.3.4.8
N-Alkylation of Simple Ureas
Urea itself and N,N
-disubstituted ureas can be conveniently utilized as versatile
and environmentally safe building blocks for the synthesis of more complex targets
containing the ureido moiety, through various reactions, including displacement of
one or both amino groups, N-alkylation, and imine/enamine formation. Some re-
cent applications are summarized below.
N,N
0
-Diphenylurea 1086 (R
O
Ph) is converted into N-phenyl-N-alkylurea 1087
in 77-92% yield by treatment with a large excess of a primary amine and a small
amount of triethylamine in DMF at reflux for 4 h [785].
ΒΌ
O
O
R'NH
2
Ph
NN
Ph
Ph
NN
R'
DMF, Et
3
N, 4h
HH
HH
77-92 %
1086
1087
The method does not proceed with hindered secondary amines, gaseous amines,
or aromatic amines bearing electron-withdrawing substituents. The latter, however,
