Chemistry Reference
In-Depth Information
via cyclization, and the resulting polymer can be converted into pMMA by hydrolysis
and esterifi cation. The pMMA exhibited optical activity ([
α
]
405
−
4.3 ° in CHCl
3
), and the
tacticity was
mm
/
mr
/
rr
= 12/49/39.
Oishi and coworkers extensively studied the polymerization properties of optically
active chiral
N
- (2 - methacryloyloxyethyl)carbamates (RMOC). They prepared a variety
of RMOCs from 2-methacryloyloxyethylisocyanate (MOI) with optically active alcohols
such as choresterol (
89
) [146] ,
l
- menthol (
90
) [146], amino alcohols (
91
-
94
) [147] , BINOL
(
95
) [148] , cinchonine (
96
) [149], and cinchonidine (
97
) [149]. Radical polymerization of
the RMOCs in the presence of AIBN afforded optically active polymers, which presum-
ably have higher-order structures arising from hydrogen bondings between urethane
moieties. However, the CD spectra indicated that chiral induction in the main chain
did not take place [148]. Polymerization of methcrylates having urea moiety (RMOU)
was also investigated: (
S
) - 1 - phenethyl (
98
) [150] , (
S
) - (methoxycarbonyl)benzylmethyl
(
99
) [150] , (
S
) - 1 - cyclohexylethyl (
100
) [151] , and (
R
) - 1 - naphthylethyl (
101
) [152] (2 -
methacryloyloxyethyl)ureas have been used as a monomer. The poly(RMOC)- and
poly(RMOU)-based chiral stationary phase resolved some racemic compounds by HPLC
[147 - 152] .
O
O
H
R
O
Ph
Ph
N
Ph
N
Ph
O
O
R =
O
H
H
O
89
90
91
92
H
H
Ph
Ph
H
N
N
O
MeO
O
N
Ph
O
N
Ph
O
H
O
H
H
Ph
Ph
N
N
93
94
95
96
97
Ph
Ph
OMe
H
H
H
H
O
98
99
100
101
13.2.2.2.2. Maleimides
Polymerization of chiral
N
- substituted maleimides (RMIs) also
gives optically active polymers. For example, the polymer obtained by asymmetric
anionic polymerization of (
R
) - (+) -
N
- (1 - phenethyl)maleimide ((
R
) - (+) -
102
) in the pres-
ence of Et
2
Zn/(
−
) -
Sp
showed an optical rotation of [
α
]
435
−
197.6 ° [153] , whereas poly[(
S
) -
(
]
435
+466.2 ° [154] . Other RMIs including
(
R
) - or (
S
) -
103
[155] , (
S
) -
104
[156] , (
R
) -
105
[157] , and (
S
) -
106
[158,159] were found to
−
) -
102
] showed a high optical rotation of up to [
α
