1
574
SCHMIDT et al.
1
1
The rate of the reaction of Pd(OAc) in the presence of
UV and B NMR spectroscopy [12]. The consumption
of the Pd compound was controlled by the decrease in
the intensity of the absorption spectrum (cell 0.1 cm,
SF-2000, 320–600 nm) of the reaction samples (the
samples were centrifuged to separate the Pd-black
precipitate). Biphenyl, a product of oxidative homo-
2
various amounts of NaOAc (2, 5, and 10 eq per 1 eq of
Pd) was found to be always 1.3–2 times higher than in
the case of phenylboronic acid III and an equilibrium
mixture of Pd(OAc) and the base. These data indicate
2
that the transmetallation stage involved not borate
anion II, as assumed earlier [4–7], but a neutral
molecule of the acid III. Note that it is in agreement
with the recent research results on the isotopic
distribution in the Suzuki–Miyaura reaction products
coupling of PhB(OH) , was detected by GLC (HP-
2
4890, DIF, column HP-5 15 m).
ACKNOWLEDGMENTS
[9].
This work was supported by the Ministry of
Education and Science within the Federal Program
On the other hand, it was found that the use of
palladium complexes containing less basic anions
“
Research and scientific-pedagogical personnel of
instead Pd(OAc) led to a significant decrease in the
2
innovative Russia” for 2009–2013 years (contract no
P1344, 02.09.2009).
reaction rate, as follows: OAc > Br >> I. In this case
no conversion in the system PdI –NaI–PhB(OH) was
2
2
observed even in the presence of a base. Special
experiments showed that the iodide complexes of
palladium were far superior in the stability than the
corresponding acetate complexes [adding an equi-
valent amount of NaI was sufficient for the quanti-
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RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 81 No. 7 2011