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

Table 2.9 Electroreductive coupling of ketones with nitrones
NITRONE REACTIONS 225
Ketone Nitrone Product % Yield
O
O
O
O
O
−
O
O
N R5 +
R 3 R 4
HO
R 1
HO
N
R 2 R 3
R 4
1 equiv. Sml2
R 5
H2O
N Bn +
O
N Bn +
O
N Bn +
O
N Bn +
O
N Bn
O
N Bn +
O
−
−
−
−
Sm III O
N R5
R3 R4 •
Sm III
O
R 1
O
N
R 2 R 3
R 4
R 5
HO N
HO
Bn
HO
N
Bn
HO
HO
N
Bn
HO
HO
N
Bn
HO
HO
N
Bn
HO
HO
N
Bn
HO
R 1
O
Scheme 2.113
R 2
R 1
1 equiv. Sml 2
R 2
69
56
42
49
56
Sm III
O N R5 O
SmIII •
O
R 1
O
N
R 2 R 3
R 4
R3 R4 •
cross-coupling, using SmI2. This method enables the preparation of highly substituted
asymmetrical vicinal N -hydroxylamino- and amino alcohols. The reaction
mechanism includes a chemoselective SET step with SmI2 at the nitrone group
with the subsequent addition of the formed intermediate to the aldehyde or ketone
(Scheme 2.113) (530).
R 5