Nitroxide Radicals: Properties, Synthesis and Applications - Stable Radicals: Fundamentals and Applied Aspects of Odd-Electron Compounds - page 194

CO 2 Me

CO 2 Me

1) H 2 ,Pd/C
2) Oxone

MeO 2 C

N MeO 2 C

N

Bn

O

H
MeO 2 C

CO 2 Me
H

1) LDA
2) CH 3 I

)- 69 135 ( ± )- 68 (43 %) ( ±

N

Bn

1) H 2 ,Pd/C
2) Oxone

MeO 2 C CO 2 Me

MeO 2 C CO 2 Me

N

N

Bn O

meso- 69 135

meso- 68 (7 %)

OMe MeO

Ph

Ph

urea.H 2 O 2
MeReO 3

1) O 2 ,Cu 2+
2) PhLi, THF
3) O 2 ,Cu 2+

PhMgBr

OMe MeO

MeO MeO

N Ph

N
H

N
O

N

THF

OMe

OH OMe

O

70 71

72 136

ee> 98 %

2HP(O)(OEt) 2
NH 3 (g)

(EtO) 2 (O)P (EtO) 2 (O)P

mCPBA

P(O)(OEt) 2 P(O)(OEt) 2

N N

CH 2 Cl 2

O O

H O

27t 138 ( ± )- 73

Scheme 5.26 Synthesis of C 2 -symmetrical chiral nitroxides

1) R 1 MgBr
THF, − 78 ° C

1) R 1 MgBr
THF,

− 78 ° C

R 1

H R 1 R 1

N 2) O 2 /Cu(OAc) 2 N N

2) O 2 /Cu(OAc) 2

O O O

74 29a
R 1 = p- H 1) R 2 MgBr

THF, − 78 ° C

C n OPh-

2) O 2 /Cu(OAc) 2

1) R 1 MgBr
THF, − 78 ° C

1) TBAF, Et 3 N
THF, 0 ° C

R 1 R 1

R 2 R 2 R 3

N 2) O 2 /Cu(OAc) 2 N

O
Cl

N

OC m H 2m + 1

O O O

20 29a

R 2 = p- TBDMSOPh-

O

R 3 = O C O C m H 2m + 1

Scheme 5.27 Synthesis of chiral nitroxides for paramagnetic liquid crystals