Page 315 - Arrow Pushing in Inorganic Chemistry A Logical Approach to the Chemistry of the Main Group Elements

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7.15 ARYL- -BROMANES 295

F
F
F
B B F
F F −
F F F F +
Br Br
(7.119)

CF 3 CF 3

The coordinated BF might then latch on to the tin of the alkynylstannane, creating an
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anionic tin center and thereby setting the stage for alkynyl migration:

Me
Me
Me
Sn Me
F Me + R
F −
C F Sn F F C
− B Me F
C − B F C
F F + C Br Me Me
R Br F F +
Br Me Sn
C
+ F +
R −
F B
F
F
CF 3
CF 3
CF
3
(7.120)
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The (alkynyl)aryl- -bromane so formed can undergo a second round of the same chemistry
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to yield a (dialkynyl)aryl- -bromane intermediate, which undergoes spontaneous reduc-
tive elimination to generate the diyne final product:
R R R
C C C
F C C C
Br Br

R C C SnMe 3
BF 3

CF
CF 3 3