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Journal of the American Chemical Society
11. For a recent report of Pd-catalyzed C–H alkylation of pyridine
23. For recent reports of C(sp2)–H alkylation with secondary alkyl
halides/tosylates, see: ref 11 (catalyzed by Pd), ref 12 (catalyzed by
Ru), ref 18c (catalyzed by Ni), ref 17b and 17c (catalyzed by Fe).
24. For selected reports on Pd-catalyzed mono-selective ortho C−H
functionalization of symmetric arenes: (a) Dai, H.-X.; Yu, J.-Q. J.
Am. Chem. Soc. 2012, 134, 134. (b) Xiao, B.; Li, Y.-M.; Liu, Z.-J.;
Yang, H.-Y.; Fu, Y. Chem. Commun. 2012, 48, 4854. (c) Chernyak,
N.; Dudnik, A. S.; Huang, C.; Gevorgyan, V. J. Am. Chem. Soc.
2010, 132, 8270.
25. For examples of mono-selective ortho C–H halogenation: (a) Mei,
T.-S.; Giri, R.; Maugel, N.; Yu, J.-Q. Angew. Chem., Int. Ed. 2008,
47, 5215. (b) Chan, K. S. L.; Wasa, M.; Wang, X.; Yu, J.-Q. Angew.
Chem., Int. Ed. 2011, 50, 9084. (c) Schröder, N.; Wencel-Delord,
J.; Glorius, F. J. Am. Chem. Soc. 2012, 134, 8298.
oxide using secondary alkyl halides: Xiao, B.; Liu, Z.-J.; Liu, L.; Fu,
Y. J. Am. Chem. Soc. 2013, 135, 616. A radical mechanism was
proposed for this reaction.
1
2
3
4
5
6
7
8
12. For a recent report of Ru-catalyzed meta-selective C–H alkylation
with secondary halides: Hofmann, N.; Ackermann, L. J. Am.
Chem. Soc. 2013, 135, 5877. An electrophilic-type substitution
mechanism was proposed for this alkylation.
13. For other metal-catalyzed C–H alkylations with alkyl halides: (a)
Vechorkin, O.; Proust, V.; Hu, X. Angew. Chem., Int. Ed. 2010, 49,
3061. (b) Chen, Q.; Ilies, L.; Nakamura, E. J. Am. Chem. Soc. 2011,
133, 428. (c) Ren, P.; Salihu, I.; Scopelliti, R.; Hu, X. Org. Lett.
2012, 14, 1748. (d) Gao, K.; Yoshikai, N. J. Am. Chem. Soc. 2013,
135, 9279.
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
14. (a) Zaitsev, V. G.; Shabashov, D.; Daugulis, O. J. Am. Chem. Soc.
2005, 127, 13154. (b) Shabashov, D.; Daugulis, O. J. Am. Chem.
Soc. 2010, 132, 3965. (c) Tran, L. D.; Daugulis, O. Angew. Chem.
Int. Ed. 2012, 51, 5188. (d) Nadres, E. T.; Santos, G. I. F.; Shabash-
ov, D.; Daugulis, O. J. Org. Chem. 2013, 78, 9689.
26. For two recent reports involving organic phosphate ligands in Pd-
catalyzed reactions: (a) Jiang, G.; Halder, R.; Fang, Y.; List, B. An-
gew. Chem., Int. Ed. 2011, 50, 9752. (b) Chai, Z.; Rainey, T. J. J.
Am. Chem. Soc. 2012, 134, 3615.
27. Since our initial report of the use of (BnO)2PO2H in Pd-catalyzed
C–H alkylation (ref 20b), several reports on its promoting effect in
Pd-catalyzed C–H functionalization have appeared. For selected
examples: (a) Ting, C. P.; Maimone, T. J. Angew. Chem. Int. Ed.
2014, 53, 3115. (b) ref 20d. (c) ref 31. (d) Wang, Q.; Han, J.;
Wang, C.; Zhang, J.; Huang, Z.; Shi, D.; Zhao, Y. Chem. Sci. 2014,
5, 4962. For a recent report of dimethyl phosphate-promoted Ir-
catalyzed allylation of aldehydes: (e) Krautwald, S.; Schafroth, M.
A.; Sarlah, D.; Carreira, E. M. J. Am. Chem. Soc. 2014, 136, 3020.
28. Electron-rich substrates are more reactive in this ortho C−H al-
kylation system.
15. For selected reports on Pd-catalyzed AQ-directed C–H function-
alizations, see: (a) Reddy, B. V. S.; Reddy, L. R.; Corey, E. J. Org.
Lett. 2006, 8, 3391. (b) Feng, Y.; Chen, G. Angew. Chem. Int. Ed.
2010, 49, 958. (c) Feng, Y.; Wang, Y.; Landgraf, B.; Liu, S.; Chen,
G. Org. Lett. 2010, 12, 3414. (d) Ano, Y.; Tobisu, M.; Chatani, N. J.
Am. Chem. Soc. 2011, 133, 12984; (e) Gutekunst, W. R.; Gianatas-
sio, R.; Baran, P. S. Angew. Chem. Int. Ed. 2012, 51, 7507. (f) Pan,
F.; Shen, P.-X.; Zhang, L.-S.; Wang, X.; Shi, Z.-J. Org. Lett. 2013,
15, 4758. (g) Shan, G.; Yang, X.; Zong, Y.; Rao, Y. Angew. Chem.
Int. Ed. 2013, 52, 13060. (h) Zhang, L.-S.; Chen, G.; Wang, X.;
Guo, Q.-Y.; Zhang, X.-S.; Pan, F.; Chen, K.; Shi, Z.-J. Angew.
Chem. Int. Ed. 2014, 53, 3899. (i) Sun, W.-W.; Cao, P.; Mei, R.-Q.;
Li, Y.; Ma, Y.-L.; Wu, B. Org. Lett. 2014, 16, 480. (j) Huang, L.;
Sun, X.; Li, Q.; Qi, C. J. Org. Chem. 2014, 79, 6720.
16. For selected examples of other metal-catalyzed AQ-directed C−H
functionalizations: (a) Shiota, H.; Ano, Y.; Aihara, Y.; Fukumoto,
Y.; Chatani, N. J. Am. Chem. Soc. 2011, 133, 14952. (b) Tran, L.
D.; Popov, I.; Daugulis, O. J. Am. Chem. Soc. 2012, 134, 18237. (c)
Nishino, M.; Hirano, K.; Satoh, T.; Miura, M. Angew. Chem. Int.
Ed. 2013, 52, 4457. (d) Shang, R.; Ilies, L.; Matsumoto, A.; Naka-
mura, E. J. Am. Chem. Soc. 2013, 135, 6030.
17. For reports on AQ-directed Fe-catalyzed C–H alkylation: (a) Asa-
ko, S.; Ilies, L.; Nakamura, E. J. Am. Chem. Soc. 2013, 135, 17755.
(b) Ilies, L.; Matsubara, T.; Ichikawa, S.; Asako, S.; Nakamura, E. J.
Am. Chem. Soc. 2014, 136, 13126. A radical mechanism was in-
voked for the C–C bond-forming step. (c) Fruchey, E. R.; Monks,
B. M.; Cook, S. P. J. Am. Chem. Soc. 2014, 136, 13130.
18. For reports on AQ-directed Ni-catalyzed C–H alkylation with
alkyl halides: (a) Aihara, Y.; Chatani, N. J. Am. Chem. Soc. 2013,
135, 5308. (b) Wu, X.; Zhao, Y.; Ge, H. J. Am. Chem. Soc. 2014,
136, 1789. A NiII/III catalytic cycle was invoked. (c) Song, W.; Lack-
ner, S.; Ackermann, L. Angew. Chem., Int. Ed. 2014, 53, 2477.
19. Rouquet, G.; Chatani, N. Angew. Chem. Int. Ed. 2013, 52, 11726.
20. (a) Zhao, Y.; Chen, G. Org. Lett. 2011, 13, 4850. (b) Zhang, S.-Y.;
He, G. Nack, W. A.; Zhao, Y.-S.; Li, Q.; Chen, G. J. Am. Chem.
Soc. 2013, 135, 2124. (c) Zhang, S.-Y.; Li, Q.; He. G.; Nack, W. A.;
Chen, G. J. Am. Chem. Soc. 2013, 135, 12135. For related Pd-
catalyzed AQ-directed C(sp3)–H alkylations: (d) Chen, K.; Hu, F.;
Zhang, S.-Q.; Shi. B.-F. Chem. Sci. 2013. 4, 3906. (e) Chen, K.; Shi,
B.-F. Angew. Chem., Int. Ed. 2014, 53, 11950.
29. O2 is not required for this reaction, but it can slightly improve the
alkylation yield.
30. It is interesting to note that the competition reaction using a 1:1
mixture of 3-MeO- and 3-CF3-benzamides (0.5/0.5 equiv) and
iPrI (3 equiv) under the general reaction conditions C gave com-
parable yields of the alkylated products 33 and 36. This may be
caused by the more favorable complexation between the ben-
zamides bearing electron-deficient aryl group and the Pd(II) cata-
lyst due to its more acidic NH. The resulting Pd/benzamide com-
plex then undergoes the ortho C−H palladation and alkylation,
which show higher reactivity for electron-rich benzamides.
31. He, G.; Zhang, S.-Y.; Nack, W. A.; Li, Q.; Chen, G. Angew. Chem.
Int. Ed. 2013, 52, 11124.
32. For selected reviews on PdIV chemistry: (a) Sehnal, P.; Taylor, R. J.;
Fairlamb, I. J. S. Chem. Rev. 2010, 110, 824. (b) Xu, L.; Li, B.;
Yang, Z.; Shi, Z. Chem. Soc. Rev. 2010, 39, 712. (c) Hickman, A. J.;
Sanford, M. S. Nature 2012, 484, 177.
33. Powers, D. C.; Ritter, T. Top. Organomet. Chem. 2011, 35, 129.
34. (a) Davies, D. L.; Donald, S. M. A.; Macgregor, S. A. J. Am. Chem.
Soc. 2005, 127, 13754. (b) Lapointe D.; Fagnou, K. Chem. Lett.
2010, 39, 1118. c) Ackmann, L. Chem. Rev. 2011, 111, 1315-1345.
35. The esterification of OAc with secondary alkyl halides is much
slower. However, the presence of carboxylate ligand did not sig-
nificantly decrease the mono-selectivity of alkylation with second-
ary alkyl halides presumably due to the more challenging sterics of
the second alkylation (see entry 19 of Table 1 vs entry 12 of Table
2).
36. For reports on carbonate and bicarbonate ligands for Pd-catalyzed
C−H functionalization: (a) García-Cuadrado, D., Braga, A. A. C.,
Maseras, F., Echavarren, A. M. J. Am. Chem. Soc. 2006, 128, 1066.
(b) Özdemir, I.; Demir, S.; Cetinkaya, B.; Gourlaouen, C.; Ma-
seras, F.; Bruneau, C.; Dixneuf, P. H. J. Am. Chem. Soc. 2008, 130,
1156. (c) Chaumontet, M.; Piccardi, R.; Audic, N.; Hitce, J.;
Peglion, J. L.; Clot, E.; Baudoin, O. J. Am. Chem. Soc. 2008, 130,
15157.
37. For a discussion on the oxidative addition of alkyl halides to met-
als, see: Stille, J. K.; Lau, K. S. Y. Acc. Chem. Res. 1977, 10, 434.
38. To the best of our knowledge, only one report on the intramolecu-
lar Catellani C−H alkylation of secondary alkyl halides has pro-
21. Wang, B.; Nack, W. A.; He, G.; Zhang, S.-Y.; Chen, G. Chem. Sci.
2014, 5, 3592.
22. For recent reviews on metal-catalyzed cross coupling of alkyl
halides: (a) Frisch, A. C.; Beller, M. Angew. Chem., Int. Ed. 2005,
44, 674. (b) Rudolph, A.; Lautens, M. Angew. Chem., Int. Ed. 2009,
48, 2656. (c) Netherton, M. R.; Fu, G. C. Top. Organomet. Chem.
2005, 14, 85.
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