COMMUNICATIONS
31,[2j] which can subsequently be converted to the
boron derivative 31a via the loss of an OPy group
under our nickel-catalyzed conditions. Similarly, the
ortho ethoxycarbonylation of 5,[2i] followed by our
borylation successfully delivered polyfunctionalized
phenylboronic ester 32a.
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Soc. Rev. 2010, 39, 712; h) P. B. Arockiam, C. Bruneau,
P. H. Dixneuf, Chem. Rev. 2012, 112, 5879; i) G. Rou-
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In summary, we report on the use of a nickel
system that can catalyze the borylation of aryl and ar-
À
ylmethyl 2-pyridyl ethers via the cleavage of C(aryl)
O bonds. Given the utility of the OPy group as a di-
[2]
À
recting group in C H functionalization reactions,
the present method broadens the synthetic utility of
the C H functionalized products to a considerable
À
extent by allowing the OPy group to be converted
into a versatile boryl group. This nickel system can
also be used to borylate more challenging secondary
benzylic substrates, in which case, the reaction pro-
ceeds with retention of configuration at the benzylic
stereocenter. This stereochemical course of the reac-
tion is complementary to the vast majority of stereo-
specific processes of chiral benzylic electrophiles,
which proceed with net inversion.[9,12] Further studies
directed to developing catalytic processes involving
boryl-metal species are currently underway in our lab-
oratories.
[2] a) F. Kakiuchi, K. Igi, M. Matsumoto, T. Hayamizu, N.
Chatani, S. Murai, Chem. Lett. 2002, 31, 396; b) J.-H.
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2012, 14, 1154; d) L. Niu, H. Yang, R. Wang, H. Fu,
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Experimental Section
Typical Procedure
NiCl2(DME) (5.5 mg, 0.025 mmol), PCy3·HBF4 (18 mg,
0.050 mmol), 2 (114 mg, 0.50 mmol), 1a (226 mg, 1.0 mmol),
K3PO4 (117 mg, 0.55 mmol), and DME (1.0 mL) were added
to a 5-mL screw-capped vial in air. The vial was then flushed
with nitrogen and the cap was closed. The mixture was
stirred at 1008C for 15 h followed by cooling to room tem-
perature. The resulting mixture was filtered through a Celite
pad (eluting with AcOEt). The filtrate was analyzed by
NMR using C2H2Cl4 as an internal standard (88% NMR
yield). The filtrate was concentrated under vacuum and pu-
rified by flash column chromatography over silica gel (elut-
ing with hexane/AcOEt=10/1) to give 2a as a white solid;
yield: 98 mg (80%).
[3] H. Kinuta, M. Tobisu, N. Chatani, J. Am. Chem. Soc.
2015, 137, 1593.
[4] Related rhodium-catalyzed inert C(aryl) O bond trans-
À
formations: a) H. Kinuta, J. Hasegawa, M. Tobisu, N.
Chatani, Chem. Lett. 2015, 44, 366; b) K. Nakamura, K.
Yasui, M. Tobisu, N. Chatani, Tetrahedron 2015, 71,
4484.
À
[5] Selected reviews on nickel-catalyzed inert C(aryl) O
bond transformations: a) B. M. Rosen, K. W. Quasdorf,
D. A. Wilson, N. Zhang, A.-M. Resmerita, N. K. Garg,
V. Percec, Chem. Rev. 2011, 111, 1346; b) D.-G. Yu, B.-
J. Li, Z.-J. Shi, Acc. Chem. Res. 2010, 43, 1486; c) B.-J.
Li, D.-G. Yu, C.-L. Sun, Z.-J. Shi, Chem. Eur. J. 2011,
17, 1728; d) M. Tobisu, N. Chatani, Top. Organomet.
Chem. 2013, 44, 35; e) J. Cornella, C. Zarate, R.
Martin, Chem. Soc. Rev. 2014, 43, 8081; f) M. Tobisu,
N. Chatani, Acc. Chem. Res. 2015, 48, 1717.
Acknowledgements
This work was supported by a Grant-in-Aid for Scientific Re-
search from MEXT, Japan and ACT-C from JST, Japan. We
also thank the Instrumental Analysis Center, Faculty of Engi-
neering, Osaka University, for their assistance with HR-MS.
[6] Nickel-catalyzed borylation of inert bonds: a) K.
Huang, D.-G. Yu, S.-F. Zheng, Z.-H. Wu, Z.-J. Shi,
Chem. Eur. J. 2011, 17, 786; b) M. Tobisu, K. Naka-
mura, N. Chatani, J. Am. Chem. Soc. 2014, 136, 5587;
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