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

REACTIONS OF DIPOLAR 1,3-CYCLOADDITION ([3 + 2] CYCLOADDITION) 315
OHC
O
O
+
NHOH
BnO O
C 6H 5
HO
NaIO 4
O H
N H
BnO
Ni Raney
OH
H
N
H2
475
O
N
H
H
O
OH
BnO OH
OCHO
CHO
OH
HO
H2, Ni Raney
OH
H
N
Scheme 2.234
474
OH
OH
R
N
O
O
1 R2 toluene,
reflux 3h N C6H5 R H
2
+
O
R1 +
−
476a,b 477a,b
O
Scheme 2.235
O
N
O
+
O−
BnO O
O
R1 O
N
H
H
O
O
BnO O
H
R 2
N O
478a,b
C6H5
R
a CH3 CH3 b CH3 H
1 R2 of nitrone structures and dipolarophiles. Examples of widely used dipolarophiles
are shown in Fig. 2.33.
Dipolarophiles D1 and D2 . In the study of steric and electronic factors on
regioselectivity and stereoselectivity of 1,3-cycloaddition of nitrones to oleÞns,
1-decene (734) and styrene derivatives (735) have been used. By comparative
analyses of the kinetic and thermodynamic parameters in the 1,3-cycloadditions