Chemistry Reference
In-Depth Information
O
O
Ph
NO
NHBoc
NHBoc
M
H
N
N
O
O
Me
CONH
2
MeS
CONH
2
MeS
NO
N
+
Sn(OTf)
2
N
Me
Ph
nonchelated
enolate
major
798
800
801
COCl
2
NaBH
4
O
O
O
O
MeS
NHBoc
NO
N
MeS
CN
Me
Ph
799
N
802
4.3.2.6
Carbamates from Isocyanides
An interesting general synthesis of carbamates is the direct reaction of isocyanides
with alcohols in the presence of thallium(III) nitrate, which offers advantages over
the preliminary oxidation of the isocyanide to an isocyanate prior to reaction with
the alcohol [583].
RNC
N
803
O
MeOH
H
3
C
R
Tl(NO
3
)
3
O
804
4.3.2.7
Potassium Carbonate as a Carbonylating Reagent
Alkyl halides can be converted to carbamates by treatment with a secondary amine
and K
2
CO
3
under phase-transfer conditions [584, 585].
K
2
CO
3
Bu
4
NH
+
HSO
4
R
1
2
NH
OCON
R
1
2
+
R
RX
805
When alkyl halides are treated with cyanate ion, the corresponding acyl isocyanates
are formed [586]; for alternative procedures, see Section 4.3.1. If the reaction is
