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R 3
R 4
R 1
O
R 3
R 4
O
R 1
R 1
P
O
P
R 2
t- Bu
R 4
R 3
CH 3 CO 3 H
O
+
NH 2
HP
+
t- Bu
C
H
N
O
t- Bu
C
N
H
H
R 2
R 2
H
SG1 22,141 : R 1 =R 2 =H,R 3 =R 4 =OEt
R 1
O
t- Bu
R 4
R 3
N
+
HP
H
R 2
O
Zn/NH 4 Cl
1) PhMgBr
2) O 2 /Cu 2+
NO 2
+
C
N
O
N
O
Ph
H
H
H
TIPNO 23,142
O
1) nBuLi / THF
2) NH 4 Cl / H 2 O
3) O 2 /Cu 2+
O
R
R
S
Et
N
O
+
S
N
O
H
Et
Et
H
75 143
R= t- Bu; R = Ph
R
N
Ph
Ph
N
O
HO
O
N
OH
H
O
77 144 R=Ph
78 144 R=Me
79 145
76 144
R=
−
CH 2 OH
80 24c
R 1 =
e
Ph
e
e
Et
e
R 1
R 2
R 2 =
e
e
e
e
Et
e
N
Ph
R 3
O
R 3 =
− (CH 2 ) 2 COMe
− (CH 2 ) 2 COMe
− (CH 2 ) 2 CONMe 2
− CH 2 OH
Et
− CH 2 - t- Bu
81 146
82 146
83 147
84 148
85 147
86 147
Scheme 5.28 Synthesis of SG1, TIPNO and some derivatives
understand the factors sustaining the very good efficiency of SG1 in the control of radical polymerization
of styrenic and acrylic monomers, Tordo et al . 22a
-hydrogen bearing nitroxides and they
found that TIPNO is also an efficient controller for nitroxide mediated polymerization. The chemistry of
TIPNO was subsequently intensively developed, 23,142 mainly by Hawker, Braslau and their coworkers, and
an impressive number of interesting derivatives were reported (Scheme 5.28: 75 , 143 76 - 78 , 144 79 - 80 , 145
81 - 82 , 146 83 and 85 - 86 , 147 84 148 ).
The Bond Dissociation Energy (BDE) of the NO-C bond of the dormant alkoxyamine is a key factor to
reach a successful controlled living polymerization in the course of nitroxide mediated polymerization. If
the bond dissociation energy is too high (around 540 kJ/mol for many monomers), at usual temperatures
tested different
α
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