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Successive transmetalation of arytrimethylsilane with Pd(II)
afford monoaryl and diaryl Pd(II) intermediates, and the
latter would easily release biaryls through reductive
elimination. In the present homocoupling reaction, we
presume that o-chlorail works as the effective bidentate
ligand and oxidant in the transmetalations, reductive
elimination and reoxidation, facilitating the otherwise
difficult homocoupling of inactive aryltrimethylsilanes. The
clarification of detailed reaction mechanism and the crucial
4
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10 role of o-chloranil are now under investigation.
11 In summary, we have developed a practical oxidative
12 homocoupling of inactive aryltrimethylsilanes by cationic
13 palladium/o-chloranil catalytic system. This catalytic system
14 enabled selective Ar–SiMe3, Ph–SiEt3 and Ph–SiMe2Ph
15 bond cleavages to afford various biaryls bearing bromo,
5
t
16 fluoro, CF3, CO2Me, Bu and OMe groups. In particular,
17 boronate group remained unreacted to furnish the bis-
18 boronate-substituted biaryls, which is otherwise difficult to
19 synthesize. We believe that the newly developed
20 homocoupling reaction of aryltrimethylsilanes will provide
21 alternative strategies for the synthesis of functionalized
22 oligoaryl fragments.
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24
This work was supported by the ERATO program from
25 JST (JPMJER1302 to K.I.), JSPS KAKENHI Grant
26 Numbers JP26810057, JP16H00907 (H.I.), and the
27 SUMITOMO Foundation (141495 to H.I.). ITbM is
28 supported by the World Premier International Research
29 Center Initiative (WPI), Japan.
30
31
This paper is dedicated to the late Professor Yoshihiko
32 Ito on the occasion of the 10th anniversary of his sudden
33 death.
34
35 Supporting
Information
is
available
on
36 http://dx.doi.org/10.1246/cl.******.
37 References and Notes
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