Chemistry Reference
In-Depth Information
O
O
R
2
O
O
O
10%
PS-BEMP
R
1
N
NuH
+
R
3
R
4
R
1
N
200% Amberlyst A15
CH
2
Cl
2
, rt, 24 h
Nu
R
3
R
2
H
(1.2 equiv)
R
4
O
O
EtOOC
N
N
Me
H
Et
Me
H
O
O
57% (dr 3 : 1)
97% (dr 3 : 1)
O
O
N
N
N
NBoc
Me
Me
O
O
83% (dr 1 : 1)
78% (dr 1 : 1)
Scheme 6.8
Tandem Michael cyclization of
b
-ketoamide derivatives
Polymer- or mesoporous silica-supported TBD reagents have also been shown to catalyse
efficiently Knoevenagel condensations and, in some cases, be feasible for continuous-flow
synthesis in a microreactor [36,37,43,44].
Due to the strong basicity, high steric hindrance and low quaternizability of polymer-
supported superbase reagents, several types of O- and N-alkylation reactions have been
reported, with the goal of contributing to combinatorial chemistry [45-58]. For example,
R
1
Z
10 mol%
PS-N3PAPT
Z
+
R
1
R
2
R
3
R
2
R
3
THF, rt
(1.5 equiv)
O
O
O
O
O
NO
2
COOMe
CN
COOEt
Me
COOMe
COOMe
NO
2
NO
2
Me
Me
96% (14 h)
84% (10 h)
76% (16 h)
87% (14 h)
94% (16 h)
Scheme 6.9
Michael addition reaction of active methine or methylene compounds
