Direct Arylation via C–H Activation - New Trends in Cross-Coupling: Theory and Applications - page 587

[RuCl 2 (C 6 H 6 )] 2 (2.5 mol%)
PPh 3
K 2 CO 3 ,NMP,120°C,20h

Br

+

N

N

N

N

PhBr(1 equiv),
K 2 CO 3 (2 equiv)
PhBr(3 equiv),
K 2 CO 3 (6 equiv)

71% 11%

0% 77%

Scheme 12.70 Ortho-arylation using an Ru II -based catalyst.

[RuCl 2 (C 6 H 6 )] 2 (2.5 mol%)
PPh 3
K 2 CO 3 ,NMP,120°C,20h

Het Het Het

+ +

Het-Br

N N

N

S S S

S S O O

equiv of
Het-Br

N N N N

71%
0%

29%
100%

1.0
2.2

99%

93%

Scheme 12.71 Ortho-arylation of 2-phenylpyridine.

[RuCl 2 (p-cymene)] 2 (2.5mol%)
(Ad 2 P(O)H) (10 mol%)
K 2 CO 3 ,NMP,120°C,5h

Ar Ar

+

Ar-Cl

N

N

OMe

CO 2 Et

CN

N N N

CN

OMe

CO 2 Et

87% 81%

85%

Scheme 12.72 Ortho-arylation of 2-phenylpyridine using a secondary phosphine
oxide.

Ackermann et al. made a significant development in Ru-catalyzed aryla-
tion when they introduced phosphine oxides [R 2 P(O)H] as a more ecient
additive than phosphine ligands (Scheme 12.72). 115 Under these conditions,