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Table 3. Substrate scope of alkynyltrimethylsilanes and
Acknowledgements
aryldiazonium tetrafluoroborates.[a]
Sina Witzel acknowledges the DOsIu: 1p0p.1o0r3t9/C8bCyC0822th7He
Landesgraduiertenförderung of the state of Baden-
Württemberg.
N2BF4
TMS
Ph3PAuNTf2 (10 mol%)
R1
Br
+
R1
MeCN, rt, blue LEDs
15-18 h
Br
7
6
8
MeO
Br
Br
Conflicts of interest
8a
8b
, 42%
, 81%
There are no conflicts to declare.
Br
Br
Notes and references
, R1 = TMS, 73%[b]
8c
1
Selected examples: (a) G. Revol, T. McCallum, M. Morin, F.
Gagosz, L. Barriault, Angew. Chem. Int. Ed., 2013, 52, 13342;
(b) J. Xie, S. Shi, T. Thang, N. Mehrkens, M. Rudolph, A. S. K
Hashmi, Angew. Chem. Int. Ed, 2015, 54, 6046; (c) J. Xie, T.
Zhang, F. Chen, N. Mehrkens, F. Rominger, M. Rudolph, A. S.
K. Hashmi, Angew. Chem. Int. Ed., 2016, 55, 2934; (d) J. Xie, J.
Li, V. Weingand, M. Rudolph, A. S. K. Hashmi, Chem. Eur. J.,
2016, 22, 12646; (e) A. Cannillo, T. R. Schwantje, M. Bégin, F.
Barabé, L. Barriault, Org. Lett., 2016, 18, 2592; (f) T.
McCallum, S. Rohe, L. Barriault, Synlett, 2016, 27, A; (g) M.
Zidan, T. McCallum. L. Thai-Savard, L. Barriault, Org. Chem.
Front, 2017, 4, 2092; (h) A. Tlahuext-Aca, M. N. Hopkinson, B.
Sahoo, F. Glorius, Chem. Sci., 2016, 7, 89; (i) Z.-S. Wang, T.-D.
Tan, C.-M. Wang, D.-Q. Yuan, T. Zhang, P. Zhu, C. Zhu, J.-M.
Zhou, L.-W. Ye, Chem. Commun., 2017, 53, 6848; (j) V.
Gauchot, D. R. Sutherland, A.-L. Lee, Chem. Sci., 2017, 8,
2885; (k) M. Zhang, C. Zhu, L.-W. Ye, Synthesis, 2017, 49,
1150.
[a] All reactions were carried out using 6 (0.3 mmol, 1.0
equiv.), 7 (0.36 mmol, 1.2 equiv.) in the presence of
Ph3PAuNTf2 (10 mol%) in MeCN (0.5 mL, 0.2M) under
irradiation with blue LEDs at room temperature. [b] 2 (0.9
mmol, 3.0 equiv.).
Fortunately, the desired cross-coupling product 8a was formed
with a yield of 81%. This yield shows a significant increase in
yield compared to the product 8a afforded by Toste et al. using
a photosensitizer 68%.6a Further, trimethyl(arylethynyl)silane
bearing an electron-donating –OMe group was tolerated to
obtain 8b in a moderate yield of 42%. Interestingly, by using
1,2-bis(trimethylsilyl)ethyne with 3.0 equivalents of 4-
bromophenyldiazonium tetrafluoroborate we obtained the
doubled cross-coupled product 8c in 73% yield. This reaction
could complement the Sonogashira coupling, particularly when
alkynyltrimethylsilanes are available rather than the
corresponding terminal alkynes and it may reveal an
advantage if non-basic conditions for an alkynyl-aryl coupling
are required.
2
(a) B. Sahoo, M. N. Hopkinson, F. Glorius, J. Am. Chem. Soc.,
2013, 135, 5505; (b) M. N. Hopkinson, A. Tlahuext-Aca, F.
Glorius, Acc. Chem. Res., 2016, 49, 2261-2272.
X.-Z. Shu, M. Zhang, Y. He, H. Frei. F. D. Toste, J. Am. Chem.
Soc., 2014, 136, 5844.
Reviews: (a) J. Mir ́o, C. del Pozo, Chem. Rev., 2016, 116,
3
4
11924; (b) Z. Zheng, Z. Wang, Y. Wang, L. Zhang, Chem. Soc.
Rev., 2016, 45, 4448; (c) K. M. Engle, T.-S. Mei, X. Wang, J.-Q.
Yu, Angew. Chem. Int. Ed., 2011, 50, 1478; (d) M. N.
Hopkinson, A. D. Gee, V. Gouverneur, Chem. Eur. J., 2011, 17,
8248; (e) H. A. Wegner and M. Auzias, Angew. Chem. Int. Ed.,
2011, 50, 8236; (f) P. Garcia, M. Malacria, C. Aubert, V.
Gandon, L. Fensterbank, ChemCatChem, 2010, 2, 493. For
selected examples, see: (g) A. S. K. Hashmi, T. D.
Ramamurthi, F. Rominger, J. Organomet. Chem., 2009, 694,
592; (h) W. Wang, J. Jasinski, G. B. Hammond, B. Xu, Angew.
Chem. Int. Ed., 2010, 49, 7247; (i) G. Zhang, L. Chui, Y. Wang,
L. Zhang, J. Am. Chem. Soc., 2010, 132, 1474; (j) J. P. Brand,
Y. Li, J. Waser, Isr. J. Chem., 2013, 53, 901; (k) J. P. Brand, J.
Waser, Angew. Chem. Int. Ed., 2010, 49, 7304; (l) T. de Haro,
C. Nevado, Synthesis, 2011, 2530; (m) W. E. Brenzovich, Jr.,
D. Benitez, A. D. Lackner, H. P. Shunatona, E. Tkatchouk, W.
A. Goddard, F. D. Toste, Angew. Chem. Int. Ed., 2010, 49,
5519.
(a) L. Huang, M. Rudolph, F. Rominger, A. S. K. Hashmi,
Angew. Chem. Int. Ed., 2016, 55, 4808; (b) L. Huang, F.
Rominger, M. Rudolph, A. S. K. Hashmi, Chem. Commun.,
2016, 52, 6435; (c) S. Witzel, J. Xie, M. Rudolph, A. S. K.
Hashmi, Adv. Synth. Catal., 2017, 359, 1522.
(a) S. Kim, J. Rojas-Martin, F. D. Toste, Chem. Sci., 2016, 7,
85; (b) I. Chakrabarty, M. O. Akram, S. Biswas, N. T. Patil,
Chem. Commun., 2018, 54, 7223.
Conclusions
In conclusion, we have extended our method from using
arylboronic acids to pinacol esters, MIDA boronates and
potassium trifluoroboronates and showed that they function
as an efficient coupling partner in the photosensitizer-free
gold-catalyzed photoredox reactions with aryldiazonium salts
and could complement the classical Suzuki reaction. Also,
organosilicon species, such as trimethoxysilanes and
bis(catecholato)silicates could be transformed by using this
method to obtain functionalized biaryls in moderate to
excellent yields. Further, we could reduce the equivalents of
aryldiazonium salt by using organotrimethylsilanes. This
reaction was tested for aryltrimethylsilanes and
alkynyltrimethylsilanes and exhibits a broad functional group
tolerance by varying the substituents on both
organotrimethylsilanes and aryldiazonium salts. Both reactions
could complement the classical palladium catalyzed cross-
couplings, for TMS-aryl compounds the Hiyama reaction and
for TMS-alkynes the Sonogashira coupling. As demonstrated,
aryl halides are well tolerated which establishes the possibility
for further functionalization, for instance, with the common
palladium chemistry.
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J. Xie, K. Sekine, S. Witzel, P. Krämer, M. Rudolph, F.
Rominger, A. S. K. Hashmi, DOI: 10.1002/anie.201806427R1
This journal is © The Royal Society of Chemistry 20xx
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