25
occurs to afford 1,4-dienes in good yields. Soon after, the palladium-catalyzed oxidative homo-coupling of 1-alkenylstannanes was reported using hexamethylphosphoric triamide as both oxidant and solvent (Scheme 2.32) [61].
N-Chlorosuccinimide, p-toluenesulfonyl chloride, and allyl acetate could also
effect as oxidant in the palladium-catalyzed oxidative homo-coupling of arylzinc
reagents, arylboronic acids, and alkynylstannanes to afford symmetrical biaryls or
1,3-diynes (Scheme  2.33) [62–64]. Using 2,2,6,6-tetramethylpiperidine-N-oxyl
radical (TEMPO) as oxidant, oxidative homo-coupling of aryl- and alkenylboronic
acids occurred smoothly via rhodium-catalysis (Scheme 2.34) [65].
RMgX
Li 2 CuCl 4 (1 mol%)
THF, r.t., 3 h
t BuN N t Bu
O
R R
R = Aryl, Alkyl, Alkynyl
X = Br, Cl
R
1 MgX
CuBr SMe 2 (2mol%)
THF, r.t., 3 h
t BuN N t Bu
O
R
1
R
2
+
R
2 MgX
F
OMe
F
F
F
F
THPO
BnO
BnO
Me
BnO
S
S
BnO
BnO
Si
Me
Br
S
TBSO
58%
7 0%
81%
75%
83%
58%
81%
8 0%
80%
69%
55%
70%
71%
80%
7 4%
76%
73%
74%
Scheme 2.29 Cu-catalyzed homo- and cross-coupling of Grignard reagents using di-tertbutyldiaziridinone as oxidant
2 Transition Metal-Catalyzed Oxidative Coupling Involving Two Organometallic…