Heterocycle Formation via Palladium-Catalyzed C–H Functionalization

Abstract

Heterocyclic compounds are ubiquitous in natural products, pharmaceuticals, and agrochemicals. Therefore, the design of novel protocols to construct heterocycles more efficiently is a major area of focus in organic chemistry. In the past several years, cyclization reactions based upon palladium-catalyzed C–H activation have received substantial attention due to their capacity for expediting heterocycle synthesis. This review discusses strategies for heterocycle synthesis via palladium-catalyzed C–H bond activation and highlights recent examples from the literature.

1 Introduction

2 Intramolecular Cyclization via C–C Bond Formation

2.1 Arene/Arene Coupling

2.1.1 C–H Arylation with Aryl Halides

2.1.2 C(sp²)–H/C(sp²)–H Coupling

2.2 Arene/Alkene Coupling or Arene/Alkyne Coupling

2.2.1 Arene/Alkene Coupling

2.2.2 Arene/Alkyne Coupling

2.3 Arene/Alkane Coupling

2.3.1 C(sp²)–H Alkylation with Alkyl Halides

2.3.2 C(sp³)–H Arylation with Aryl Halides

2.3.3 C(sp²)–H/C(sp³)–H Coupling

3 Intramolecular Cyclization via C–N Bond Formation

4 Intramolecular Cyclization via C–O or C–S Bond Formation

5 Incorporation with Carbon Monoxide

6 Incorporation with Isonitrile

7 Incorporation with Olefin

8 Conclusions

Key words

heterocycle - C–H activation - arylation - alkylation - amination - carbonylation - olefination

• References


For selected reviews of methodology for constructing heterocycles using traditional cross-coupling reactions, see:
• 1a Metal-Catalyzed Cross-Coupling Reactions. Diederich F, Stang PJ. Wiley-VCH; New York: 1998
• 1b Nakamura I, Yamamoto Y. Chem. Rev. 2004; 104: 2127
• 1c Cacchi S, Fabrizi G. Chem. Rev. 2005; 105: 2873
• 1d Zeni G, Larock RC. Chem. Rev. 2006; 106: 4644
• 1e Nicolaou KC, Bulger PG, Sarlah D. Angew. Chem. Int. Ed. 2005; 44: 4442

For selected reviews on transition-metal-catalyzed C–H activation reactions, see:
• 2a Crabtree RH. Chem. Rev. 1985; 85: 245
• 2b Shilov AE, Shul’pin GB. Chem. Rev. 1997; 97: 2879
• 2c Jia C, Kitamura T, Fujiwara Y. Acc. Chem. Res. 2001; 34: 633
• 2d Ritleng V, Sirlin C, Pfeffer M. Chem. Rev. 2002; 102: 1731
• 2e Labinger JA, Bercaw JE. Nature (London) 2002; 417: 507
• 2f Kakiuchi F, Chatani N. Adv. Synth. Catal. 2003; 345: 1077
• 2g Yu J.-Q, Giri R, Chen X. Org. Biomol. Chem. 2006; 4: 4041
• 2h Dick AR, Sanford MS. Tetrahedron 2006; 62: 2439
• 2i Bergman RG. Nature (London) 2007; 446: 391
• 2j Hartwig JF. Nature (London) 2008; 455: 314
• 2k Colby DA, Bergman RG, Ellman JA. Chem. Rev. 2010; 110: 624
• 2l Lyons TW, Sanford MS. Chem. Rev. 2010; 110: 1147
• 2m Yeung CS, Dong VM. Chem. Rev. 2011; 111: 1215

For perspectives on atom-, step-, and redox-economy, respectively, see:
• 3a Trost BM. Science (Washington, D.C.) 1991; 254: 1471
• 3b Wender PA, Verma VA, Paxton TJ, Pillow TH. Acc. Chem. Res. 2008; 41: 40
• 3c Burns NZ, Baran PS, Hoffmann RW. Angew. Chem. Int. Ed. 2009; 48: 2854

For selected reviews of methodology for constructing heterocycles by transition-metal-catalyzed C–H functionalization, see:
• 4a Thansandote P, Lautens M. Chem.–Eur. J. 2009; 15: 5874
• 4b Zhang M. Adv. Synth. Catal. 2009; 351: 2243
• 4c Beccalli EM, Broggini G, Fasana A, Rigamonti M. J. Organomet. Chem. 2011; 696: 277
• 4d Stokes BJ, Driver TG. Eur. J. Org. Chem. 2011; 4071

For selected reviews on synthetic applications of C–H bond functionalization, see:
• 4e Gutekunst WR, Baran PS. Chem. Soc. Rev. 2011; 40: 1976
• 4f Engle KM, Yu J.-Q. Transition-Metal-Catalyzed C–H Functionalization: Synthetically Enabling Reactions for Building Molecular Complexity. In Organic Chemistry – Breakthroughs and Perspectives. Ding K, Dai L.-X. Wiley-VCH; Weinheim: 2012

For selected reviews of Pd-catalyzed C–H activation/C–C bond formation, see:
• 5a Campeau L.-C, Stuart DR, Fagnou K. Aldrichimica Acta 2007; 40: 35
• 5b Li B.-J, Yang S.-D, Shi Z.-J. Synlett 2008; 949
• 5c Chen X, Engle KM, Wang D.-H, Yu J.-Q. Angew. Chem. Int. Ed. 2009; 48: 5094
• 5d Daugulis O, Do H.-Q, Shabashov D. Acc. Chem. Res. 2009; 42: 1074

For reviews of methodology for constructing heterocycles via Pd-catalyzed C–H activation arene/arene coupling, see:
• 6a Hassan J, Sévignon M, Gozzi C, Schulz E, Lemaire M. Chem. Rev. 2002; 102: 1359
• 6b Harayama T. Heterocycles 2005; 65: 697
• 6c Campeau L.-C, Fagnou K. Chem. Commun. 2006; 1253
• 6d Seregin IV, Gevorgyan V. Chem. Soc. Rev. 2007; 36: 1173
• 6e Alberico D, Scott ME, Lautens M. Chem. Rev. 2007; 107: 174
• 6f Ackermann L, Vicente R, Kapdi AR. Angew. Chem. Int. Ed. 2009; 48: 9792

For mechanistic studies of C–H cleavage by Pd(II), see:
• 7a Ryabov AD, Sakodinskaya IK, Yatsimirsky AK. J. Chem. Soc., Dalton Trans. 1985; 2629
• 7b Canty AJ, van Koten G. Acc. Chem. Res. 1995; 28: 406
• 7c Gómez M, Granell J, Martinez M. J. Chem. Soc., Dalton Trans. 1998; 37
• 7d Davies DL, Donald SM. A, Macgregor SA. J. Am. Chem. Soc. 2005; 127: 13754
• 7e For a recent review, see: Lapointe D, Fagnou K. Chem. Lett. 2010; 39: 1118

For early examples of heterocycle formation via Pd-catalyzed C–H arylation, see:
• 8a Ames DE, Bull D. Tetrahedron 1982; 38: 383
• 8b Ames DE, Opalko A. Synthesis 1983; 234
• 8c Ames DE, Opalko A. Tetrahedron 1984; 40: 1919
• 9 Hennings DD, Iwasa S, Rawal VH. J. Org. Chem. 1997; 62: 2
• 10a Campeau L.-C, Parisien M, Leblanc M, Fagnou K. J. Am. Chem. Soc. 2004; 126: 9186
• 10b Campeau L.-C, Thansandote P, Fagnou K. Org. Lett. 2005; 7: 1857
• 10c Campeau L.-C, Parisien M, Jean A, Fagnou K. J. Am. Chem. Soc. 2006; 128: 581
• 11 Shiotani A, Itatani H. Angew. Chem. Int. Ed. 1974; 13: 471
• 12 Dwight TA, Rue NR, Charyk D, Josselyn R, DeBoef B. Org. Lett. 2007; 9: 3137

For early examples of biaryl formations via Pd-catalyzed intermolecular C–H/C–H cross-coupling, see:
• 13a Li R, Jiang L, Lu W. Organometallics 2006; 25: 5973
• 13b Stuart DR, Fagnou K. Science (Washington, D.C.) 2007; 316: 1172
• 13c Stuart DR, Villemure E, Fagnou K. J. Am. Chem. Soc. 2007; 129: 12072
• 13d Hull KL, Sanford MS. J. Am. Chem. Soc. 2007; 129: 11904
• 14 Liégault B, Lee D, Huestis MP, Stuart DR, Fagnou K. J. Org. Chem. 2008; 73: 5022
• 15 Sridharan V, Martín MA, Menéndez JC. Eur. J. Org. Chem. 2009; 4614
• 16a Watanabe T, Ueda S, Inuki S, Oishi S, Fujii N, Ohno H. Chem. Commun. 2007; 4516
• 16b Watanabe T, Oishi S, Fujii N, Ohno H. J. Org. Chem. 2009; 74: 4720
• 17 Liégault B, Fagnou K. Organometallics 2008; 27: 4841
• 18 Yeung CS, Zhao X, Borduas N, Dong VM. Chem. Sci. 2010; 1: 331
• 19 Ackermann L, Jeyachandran R, Potukuchi HK, Novák P, Büttner L. Org. Lett. 2010; 12: 2056
• 20 Pintori DG, Greaney MF. J. Am. Chem. Soc. 2011; 133: 1209
• 21 Iida H, Yuasa Y, Kibayashi C. J. Org. Chem. 1980; 45: 2938
• 22 Åkermark B, Oslob JD, Heuschert U. Tetrahedron Lett. 1995; 36: 1325
• 23 Zhang H, Ferreira EM, Stoltz BM. Angew. Chem. Int. Ed. 2004; 43: 6144
• 24 Schiffner JA, Oestreich M. Eur. J. Org. Chem. 2011; 1148
• 25 Li C, Zhang Y, Li P, Wang L. J. Org. Chem. 2011; 76: 4692

For examples of Pd(II)-catalyzed intramolecular C–H olefination with nitrogen-containing heterocycles, see:
• 26a Ferreira EM, Stoltz BM. J. Am. Chem. Soc. 2003; 125: 9578
• 26b Beccalli EM, Broggini G. Tetrahedron Lett. 2003; 44: 1919
• 26c Liu C, Widenhoefer RA. J. Am. Chem. Soc. 2004; 126: 10250

For examples of C–H activation followed by enantioselective addition to a tethered olefin, see:
• 26d Schiffner JA, Machotta AB, Oestreich M. Synlett 2008; 2271
• 26e Schiffner JA, Wöste TH, Oestreich M. Eur. J. Org. Chem. 2010; 174

For applications of Pd(II)-mediated intramolecular C–H olefination with nitrogen-containing heterocycles in total synthesis, see:
• 27a Trost BM, Godleski SA, Genêt JP. J. Am. Chem. Soc. 1978; 100: 3930
• 27b Cushing TD, Sanz-Cervera JF, Williams RM. J. Am. Chem. Soc. 1993; 115: 9323
• 27c Baran PS, Corey EJ. J. Am. Chem. Soc. 2002; 124: 7904
• 27d Garg NK, Caspi DD, Stoltz BM. J. Am. Chem. Soc. 2004; 126: 9552
• 27e Beck EM, Hatley R, Gaunt MJ. Angew. Chem. Int. Ed. 2008; 47: 3004
• 27f Bowie AL. Jr, Trauner D. J. Org. Chem. 2009; 74: 1581
• 28a Jia C, Piao D, Oyamada J, Lu W, Kitamura T, Fujiwara Y. Science (Washington, D.C.) 2000; 287: 1992
• 28b Jia C, Piao D, Kitamura T, Fujiwara Y. J. Org. Chem. 2000; 65: 7516
• 29 Pinto A, Neuville L, Retailleau P, Zhu J. Org. Lett. 2006; 8: 4927
• 30 Tang D.-J, Tang B.-X, Li J.-H. J. Org. Chem. 2009; 74: 6749
• 31 Hennessy EJ, Buchwald SL. J. Am. Chem. Soc. 2003; 125: 12084
• 32 Petronijevic FR, Wipf P. J. Am. Chem. Soc. 2011; 133: 7704

For early examples of C(sp³)–H activation/arylation, see:
• 33a Dyker G. Angew. Chem. Int. Ed. 1992; 31: 1023
• 33b Dyker G. J. Org. Chem. 1993; 58: 6426
• 33c Dyker G. Angew. Chem. Int. Ed. 1999; 38: 1698

For reviews of C(sp³)–H activation/arylation, see:
• 33d Jazzar R, Hitce J, Renaudat A, Sofack-Kreutzer J, Baudoin O. Chem.–Eur. J. 2010; 16: 2654
• 33e Baudoin O. Chem. Soc. Rev. 2011; 40: 4902
• 34a Lafrance M, Gorelsky SI, Fagnou K. J. Am. Chem. Soc. 2007; 129: 14570
• 34b For mechanistic studies, see: Rousseaux S, Davi M, Sofack-Kreutzer J, Pierre C, Kefalidis CE, Clot E, Fagnou K, Baudoin O. J. Am. Chem. Soc. 2010; 132: 10706
• 35 Watanabe T, Oishi S, Fujii N, Ohno H. Org. Lett. 2008; 10: 1759
• 36a Nakanishi M, Katayev D, Besnard C, Kündig EP. Angew. Chem. Int. Ed. 2011; 50: 7438
• 36b Anas S, Cordi A, Kagan HB. Chem. Commun. 2011; 47: 11483
• 37 Rousseaux S, Gorelsky SI, Chung BK. W, Fagnou K. J. Am. Chem. Soc. 2010; 132: 10692

For selected examples of intermolecular C(sp³)–H arylation, see:
• 38a Zaitsev VG, Shabashov D, Daugulis O. J. Am. Chem. Soc. 2005; 127: 13154
• 38b Reddy BV. S, Reddy LR, Corey EJ. Org. Lett. 2006; 8: 3391
• 38c Giri R, Maugel N, Li J.-J, Wang D.-H, Breazzano SP, Saunders LB, Yu J.-Q. J. Am. Chem. Soc. 2007; 129: 3510
• 38d Wasa M, Engle KM, Yu J.-Q. J. Am. Chem. Soc. 2009; 131: 9886
• 38e Shabashov D, Daugulis O. J. Am. Chem. Soc. 2010; 132: 3965
• 38f Feng Y, Chen G. Angew. Chem. Int. Ed. 2010; 49: 958
• 38g He G, Chen G. Angew. Chem. Int. Ed. 2011; 50: 5192
• 38h Gutekunst WR, Baran PS. J. Am. Chem. Soc. 2011; 133: 19076
• 38i Tran LD, Daugulis O. Angew. Chem. Int. Ed. 2012; DOI: 10.1002/anie.201200731.
• 39 Feng Y, Wang Y, Landgraf B, Liu S, Chen G. Org. Lett. 2010; 12: 3414

For initial reports of the Buchwald–Hartwig amination reaction, see:
• 40a Paul F, Patt J, Hartwig JF. J. Am. Chem. Soc. 1994; 116: 5969
• 40b Guram AS, Buchwald SL. J. Am. Chem. Soc. 1994; 116: 7901

For early studies concerning C–N bond formation using Pd(0), see:
• 40c Kosugi M, Kameyama M, Migita T. Chem. Lett. 1983; 12: 927
• 40d Boger DL, Panek JS. Tetrahedron Lett. 1984; 25: 3175
• 41 For pioneering work in Pd-catalyzed C–H amination, see: Tsang WC. P, Zheng N, Buchwald SL. J. Am. Chem. Soc. 2005; 127: 14560

For mechanistic studies and applications of the transformation, see:
• 42a Tsang WC. P, Munday RH, Brasche G, Zheng N, Buchwald SL. J. Org. Chem. 2008; 73: 7603
• 42b For another application of this transformation, see: Li B.-J, Tian S.-L, Fang Z, Shi Z.-J. Angew. Chem. Int. Ed. 2008; 47: 1115

For carbazole formation via Pd-catalyzed C–H amination, see:
• 43a Jordan-Hore JA, Johansson CC. C, Gulias M, Beck EM, Gaunt MJ. J. Am. Chem. Soc. 2008; 130: 16184
• 43b Youn SW, Bihn JH, Kim BS. Org. Lett. 2011; 13: 3738

For carbazole formation via a radical cyclization approach, see:
• 43c Cho SH, Yoon J, Chang S. J. Am. Chem. Soc. 2011; 133: 5996
• 43d Antonchick AP, Samanta R, Kulikov K, Lategahn J. Angew. Chem. Int. Ed. 2011; 50: 8605
• 43e For an early example of hypervalent-iodine-mediated radical cyclization, see: Togo H, Hoshina Y, Yokoyama M. Tetrahedron Lett. 1996; 37: 6129
• 44 Inamoto K, Saito T, Katsuno M, Sakamoto T, Hiroya K. Org. Lett. 2007; 9: 2931
• 45a Inamoto K, Saito T, Hiroya K, Doi T. Synlett 2008; 3157
• 45b Inamoto K, Saito T, Hiroya K, Doi T. J. Org. Chem. 2010; 75: 3900
• 45c Xiao Q, Wang W.-H, Liu G, Meng F.-K, Chen J.-H, Yang Z, Shi Z.-J. Chem.–Eur. J. 2009; 15: 7292
• 45d Inamoto K, Hasegawa C, Kawasaki J, Hiroya K, Doi T. Adv. Synth. Catal. 2010; 352: 2643
• 45e Wang G.-W, Yuan T.-T, Li D.-D. Angew. Chem. Int. Ed. 2011; 50: 1380
• 46 Wasa M, Yu J.-Q. J. Am. Chem. Soc. 2008; 130: 14058

For selected examples for allylic amination, see:
• 47a Fraunhoffer KJ, White MC. J. Am. Chem. Soc. 2007; 129: 7274
• 47b Reed SA, White MC. J. Am. Chem. Soc. 2008; 130: 3316
• 47c Liu G, Yin G, Wu L. Angew. Chem. Int. Ed. 2008; 47: 4733
• 48 Miura T, Ito Y, Murakami M. Chem. Lett. 2009; 38: 328

For selected examples of Pd-catalyzed fluorination using F⁺, see:
• 49a Hull KL, Anani WQ, Sanford MS. J. Am. Chem. Soc. 2006; 128: 7134
• 49b Wang X, Mei T.-S, Yu J.-Q. J. Am. Chem. Soc. 2009; 131: 7520
• 49c Chan KS. L, Wasa M, Wang X, Yu J.-Q. Angew. Chem. Int. Ed. 2011; 50: 9081

For studies on C–F reductive elimination from Pd(IV) complexes, see:
• 49d Yahav A, Goldberg I, Vigalok A. J. Am. Chem. Soc. 2003; 125: 13634
• 49e Kaspi AW, Yahav-Levi A, Goldberg I, Vigalok A. Inorg. Chem. 2008; 47: 5
• 49f Furuya T, Ritter T. J. Am. Chem. Soc. 2008; 130: 10060
• 49g Ball ND, Sanford MS. J. Am. Chem. Soc. 2009; 131: 3796
• 49h Furuya T, Benitez D, Tkatchouk E, Strom AE, Tang P, Goddard III WA, Ritter T. J. Am. Chem. Soc. 2010; 132: 3793
• 50 Mei T.-S, Wang X, Yu J.-Q. J. Am. Chem. Soc. 2009; 131: 10806
• 51 For a review of bystanding F⁺ oxidants, see: Engle KM, Mei T.-S, Wang X, Yu J.-Q. Angew. Chem. Int. Ed. 2011; 50: 1478
• 52a Haffemayer B, Gulias M, Gaunt MJ. Chem. Sci. 2011; 2: 312
• 52b He G, Zhao Y, Zhang S, Lu C, Chen G. J. Am. Chem. Soc. 2012; 134: 3
• 52c Nadres ET, Daugulis O. J. Am. Chem. Soc. 2012; 134: 7
• 53 For C–H amination via Pd(0)/Pd(II) catalysis, see: Tan Y, Hartwig JF. J. Am. Chem. Soc. 2010; 132: 3676

For examples of Pd-catalyzed C(sp³)–H amination, see:
• 54a Thu H.-Y, Yu W.-Y, Che C.-M. J. Am. Chem. Soc. 2006; 128: 9048
• 54b Pan J, Su M, Buchwald SL. Angew. Chem. Int. Ed. 2011; 50: 8647
• 55 Neumann JJ, Rakshit S, Dröge T, Glorius F. Angew. Chem. Int. Ed. 2009; 48: 6892
• 56 Wang X, Lu Y, Dai H.-X, Yu J.-Q. J. Am. Chem. Soc. 2010; 132: 12203
• 57 Xiao B, Gong T.-J, Liu Z.-J, Liu J.-H, Luo D.-F, Xu J, Liu L. J. Am. Chem. Soc. 2011; 133: 9250
• 58 Inamoto K, Hasegawa C, Hiroya K, Doi T. Org. Lett. 2008; 10: 5147
• 59 Joyce LL, Batey RA. Org. Lett. 2009; 11: 2792
• 60 Samanta R, Antonchick AP. Angew. Chem. Int. Ed. 2011; 50: 5217

For selected reviews of palladacycle carbonylation, see:
• 61a Ryabov AD. Synthesis 1985; 233
• 61b Ref. 6b
• 61c For recent examples, see: Vicente J, Saura-Llamas I, García-López J.-A, Calmuschi-Cula B. Organometallics 2007; 26: 2768
• 61d Vicente J, Saura-Llamas I, García-López J.-A, Bautista D. Organometallics 2009; 28: 448
• 61e Vicente J, González-Herrero P, Frutos-Pedreño R, Chicote M.-T, Jones PG, Bautista D. Organometallics 2011; 30: 1079
• 61f For selected reviews of Pd(II)-catalyzed C–H carbonylation of benzene, see: Fujiwara Y, Tabaki K, Taniguchi Y. Synlett 1996; 591
• 61g See also ref. 2c
• 62 For the first report of lactam formation via Pd-catalyzed C–H carbonylation, see: Orito K, Horibata A, Nakamura T, Ushito H, Nagasaki H, Yuguchi M, Yamashita S, Tokuda M. J. Am. Chem. Soc. 2004; 126: 14342
• 63a Wada Y, Nagasaki H, Tokuda M, Orito K. J. Org. Chem. 2007; 72: 2008
• 63b Yamashita S, Kurono N, Senboku H, Tokuda M, Orito K. Eur. J. Org. Chem. 2009; 1173
• 64a Mei T.-S, Giri R, Maugel N, Yu J.-Q. Angew. Chem. Int. Ed. 2008; 47: 5215
• 64b Mei T.-S, Wang D.-H, Yu J.-Q. Org. Lett. 2010; 12: 3140
• 64c For a review of directed Pd-catalyzed C–H via weak coordination, see: Engle KM, Mei T.-S, Wasa M, Yu J.-Q. Acc. Chem. Res. 2012; DOI: 10.1021/ar200185g.
• 65 Giri R, Yu J.-Q. J. Am. Chem. Soc. 2008; 130: 14082
• 66a Houlden CE, Hutchby M, Bailey CD, Ford JG, Tyler SN. G, Gagné MR, Lloyd-Jones GC, Booker-Milburn KI. Angew. Chem. Int. Ed. 2009; 48: 1830
• 66b Giri R, Lam JK, Yu J.-Q. J. Am. Chem. Soc. 2010; 132: 686
• 67 López B, Rodriguez A, Santos D, Albert J, Ariza X, Garcia J, Granell J. Chem. Commun. 2011; 47: 1054
• 68 Ma B, Wang Y, Peng J, Zhu Q. J. Org. Chem. 2011; 76: 6362
• 69 Lu Y, Leow D, Wang X, Engle KM, Yu J.-Q. Chem. Sci. 2011; 2: 967

For selected examples highlighting the effects of amino acid ligands in Pd-catalyzed C–H activation, see:
• 70a Shi B.-F, Maugel N, Zhang Y.-H, Yu J.-Q. Angew. Chem. Int. Ed. 2008; 47: 4882
• 70b Shi B.-F, Zhang Y.-H, Lam JK, Wang D.-H, Yu J.-Q. J. Am. Chem. Soc. 2010; 132: 460
• 70c Engle KM, Wang D.-H, Yu J.-Q. J. Am. Chem. Soc. 2010; 132: 14137
• 71 For the sole example of Pd(II)-catalyzed C(sp³)–H carbonylation reported to date, see: Yoo EJ, Wasa M, Yu J.-Q. J. Am. Chem. Soc. 2010; 132: 17378
• 72 Wang Y, Wang H, Peng J, Zhu Q. Org. Lett. 2011; 13: 4604

For early reports of Pd(II)-mediated C(aryl)–H olefination, see:
• 73a Moritani I, Fujiwara Y. Tetrahedron Lett. 1967; 8: 1119
• 73b Fujiwara Y, Moritani I, Matsuda M, Teranishi S. Tetrahedron Lett. 1968; 9: 633
• 73c Fujiwara Y, Noritani I, Danno S, Asano R, Teranishi S. J. Am. Chem. Soc. 1969; 91: 7166

For selected examples of Pd-catalyzed C–H olefination using directing groups, see:
• 73d Diamond SE, Szalkiewicz A, Mares F. J. Am. Chem. Soc. 1979; 101: 490
• 73e Miura M, Tsuda T, Satoh T, Nomura M. Chem. Lett. 1997; 1103
• 73f Boele MD. K, van Strijdonck GP. F, de Vries AH. M, Kamer PC. J, de Vries JG, van Leeuwen PW. N. M. J. Am. Chem. Soc. 2002; 124: 1586
• 74 Larock RC, Varaprath S, Lau HH, Fellows CA. J. Am. Chem. Soc. 1984; 106: 5274
• 75 Miura M, Tsuda T, Satoh T, Pivsa-Art S, Nomura M. J. Org. Chem. 1998; 63: 5211
• 76 Houlden CE, Bailey CD, Ford JG, Gagné MR, Lloyd-Jones GC, Booker-Milburn KI. J. Am. Chem. Soc. 2008; 130: 10066
• 77 Li J.-J, Mei T.-S, Yu J.-Q. Angew. Chem. Int. Ed. 2008; 47: 6452
• 78 Lu Y, Wang D.-H, Engle KM, Yu J.-Q. J. Am. Chem. Soc. 2010; 132: 5916
• 79 Zhu C, Falck JR. Org. Lett. 2011; 13: 1214
• 80 For the first example of Pd(II)-catalyzed C(sp³)–H olefination, see: Wasa M, Engle KM, Yu J.-Q. J. Am. Chem. Soc. 2010; 132: 3680
• 81 Stowers KJ, Fortner KC, Sanford MS. J. Am. Chem. Soc. 2011; 133: 6541