Early Transition Metal Catalyzed Living Radical and Ring

Cl O O Cp2Cl Ti O CH2 CH2 R ClCp2 Ti CH CH2 OC O CH2 O ClCp2Ti 5 n R H2C C CH3 CO O CH2 CH H2C C CH3 CO O CH2 HC OH CH2 ...
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Early Transition Metal Catalyzed Living Radical and Ring Opening Polymerizations for Complex Copolymer Architectures Alexandru D. Asandei, University of Connecticut, Department of Chemistry, Storrs CT, 06269

The Cp2TiCl mediated radical ring opening of epoxides, SET reduction of aldehydes, halide activation and redox reaction with peroxides were demonstrated as novel initiating methodologies for the living radical polymerization (LRP) of styrene, living ring opening polymerization of lactones and for the synthesis of complex polymer architectures.

O

H B

R5

Cl

Styrene Ti(III) LRP

O

N

N

N N

N

N

Ti

n

Cl

Ti Cl

Cl

~Pn

+ Ti Cp2Cl

kp, M

Cl Ti

X

R

Cl

O

KDC

TiCp2Cl

H+ X

HO-Pn-H

16000

2

12000

1.75

X = H, Cl, tBu, MeO

Cp2Cl Ti O CH2 CH2 R O O R-X H R' R

PDI

X Ti

CH2 CH

Mn

R

Cp2Cl Ti O CH2 CH R

8000

1.5

4000

1.25

0

1 0

0.5

1

Conversion (%)

Cl

e-CL ROP

10

12

14 16 elution time, min

18

20

O O O

ClCp2Ti O

O CH2 C O CH2 CH Ti ClCp2 5 n R

St, Lact PGMA

O O

Styrene O

GMA O

O

O

O

O

O O

CH2 CH R

O

O

O

O

O

H2C

O

O

O

O Cl Ti

H2C

CH O

O

CH2

n-1

Cl

Ti

O

O

CH3

C H2C

C H2C C C O

C O

O

O

O

CH2

CH2

CH2

C

O

m-1

CH3

CH3 O

HC

CH3 C C O

OH HC CH2 C CH2

CH2 CH2 O

CH3

CH2 OH

C O

O