Nitrile Oxides, Nitrones, and Nitronates in Organic Synthesis : Novel ...

O −
O −
N +
H
N +
H
METHODS FOR GENERATION AND PREPARATION OF NITRILE OXIDES 11
O
O
R C CH i. AuCl3 or H +
+
+
−
ii. NO2
O −
N O
R C CH2
ONO
O O
Scheme 1.8
AuCl3 or H +
O −
+ +
OR OR
N O O− N
R 1
O −
R 2
+ +
Scheme 1.9
R CO CNO
RCO
O N
N
O
R C CH
O
15
CNO2
O
R1 = NO2, R2 = H
R1 = H, R2 = NO2 N
OHC
HC
+
R
O OR
H
CHO
Dehydration of O-silylated hydroxamic acids is used as a general method in
the synthesis of nitrile oxides (95) in the presence of trißuoromethanesulfonic
anhydride and triethylamine.
Methoxycarbonylformonitrile oxide is smoothly generated by β-elimination
of methanol from E-N-methoxy-N-(methoxycarbonylmethylene)amine N-oxide,
MeO2CCH=N(OMe)O, in the presence of a catalytic amount of boron trißuoride
etherate (96).
Phosphorylated and thiophosphorylated diazo compounds, i-Pr2P(X)C(N2)
SiMe3 (X = O, S) react with nitrosyl chloride to give α-nitroso-diazo derivatives