New Cycloaddition Reactions of Anionically Activated Dipoles Daesung Lee, Department of Chemistry, University of Illinois at Chicago, IL 60607 New reactions of anionic dipoles: Based on the high reactivity of an anionic form of trimethylsilyldiazomethane, various unprecedented transformations were developed. These include cycloaddition, tandem cycloaddition–1,2addition–cycloaddition, and cycloaddition–1,2-addition–fragmentation starting from α,β-unsaturated ketones. OH
-78 ¡C, 20 min; SiO2
O H N N
2
e
q
u
i
N N
O
73%
N H Me3SiO
H H N N
SiMe3
Li
Cl
SiMe3
72%
O 1 equiv
H N
v
SiMe3
N2
.
SiMe3
OMe
+
R H N N
2 equiv
O
H
SiMe3
N
OSiMe3 H N
N
-78 ¡C, 20 min to 25 °C; SiO2 R = H, 81% R = Cl, 93% R = OMe, 79%
N
65% H SiMe3
R
. .
Cyclopropenation via C–Si bond insertion: The reaction of lithiated trimethyldiazomethane was further expanded to its reaction with α-silylketones, which leads to the unprecedented C–Si bond insertion to genertaed silylated cyclopropenes. .
N2 O H
SiMe3
N2 O
H R
InCl3
Me3Si
SiMe3 Li
R
Me3Si
R
! =
Me3Si
R .
