Radical Cation Salts: From Single-Electron Oxidation to C–H Activation­

Dedicated to my mother, Fengying Zhang, for her selfless love

Abstract

This short review describes the work performed by my group on reactions initiated by radical cation salts. In our early studies, transformations based on single-electron oxidations induced by radical cation salts were investigated. More recently, we focused on aerobic oxidations of C–H bonds promoted by radical cation salts. In this work, we elucidate the mechanism, determine the scope, and discuss the potential future applications of radical cation salts in efficient transformations of C–H bonds.

1 Introduction

2 Widely Used Radical Cation Salts

3 Single-Electron Oxidation Induced by Radical Cation Salts

3.1 General Mechanism

3.2 Oxidation of Alkenes

3.3 Oxidation of N-Vinylamines and N-Vinylamides

3.4 Oxidation of Vinyl Ethers

3.5 Oxidation of Imines

4 C–H Activation Induced by Radical Cation Salts

4.1 Oxidation of Glycine Derivatives

4.2 Oxidation of N-Benzylanilines

4.3 Oxidation of 1,4-Dihydropyridines

5 Outlook

Key words

radical reactions - oxidation - electron transfer - heterocycles - cycloaddition

• References

• 1a Wurster C, Sendtner R. Ber. Dtsch. Chem. Ges. 1879; 12: 1803
• 1b Wurster C. Ber. Dtsch. Chem. Ges. 1879; 12: 2071
• 2 Gomberg M. J. Am. Chem. Soc. 1900; 22: 757
• 3a Weitz E, Schwechten HW. Ber. Dtsch. Chem. Ges. 1926; 59: 2307
• 3b Weitz E, Schwechten HW. Ber. Dtsch. Chem. Ges. 1927; 60: 545
• 4a Bell FA, Ledwith A, Sherrington DC. J. Chem. Soc. C 1969; 2719
• 4b Boduszek B, Shine HJ. J. Org. Chem. 1988; 53: 5142
• 4c Rathore R, Abdelwahed SH, Guzei LA. J. Am. Chem. Soc. 2004; 126: 13582
• 4d Debroy P, Shukla R, Lindeman SV, Rathore R. J. Org. Chem. 2007; 72: 1765
• 4e Douadi T, Cariou M, Simonet J. Tetrahedron 1996; 52: 4449
• 4f Hiraoka S, Okamoto T, Kozaki M, Shiomi D, Sato K, Takui T, Okada K. J. Am. Chem. Soc. 2004; 126: 58
• 4g Rathore R, Burns CL, Deselnicu MI. Org. Lett. 2001; 3: 2887
• 4h Rathore R, Burns CL, Deselnicu MI. Org. Synth. 2005; 82: 1
• 5a Bauld NL. Tetrahedron 1989; 45: 5307
• 5b Schmittel M, Burghart A. Angew. Chem. Int. Ed. 1997; 36: 2550
• 5c Nelsen SF. Acc. Chem. Res. 1987; 20: 269
• 6 Bauld NL, Aplin JT, Yueh W, Loinaz A. J. Am. Chem. Soc. 1997; 119: 11381
• 7a Bauld NL, Pabon R. J. Am. Chem. Soc. 1983; 105: 633
• 7b Eberson L, Olofsson B. Acta Chem. Scand. 1991; 45: 316
• 8a Eberson L. Electron Transfer Reactions in Organic Chemistry. Springer; Berlin: 1987: 172
• 8b Bauld NL In Advances in Electron Transfer Chemistry . Vol. 2. Mariano PS. Jai Press; London: 1992
• 8c Studer A, Curran DP. Nat. Chem. 2014; 6: 765
• 9 Jia X.-D, Lin H.-C, Huo C.-D, Zhang W, Lü J.-M, Yang L, Zhao G.-Y, Liu Z.-L. Synlett 2003; 1707
• 10 Jia X.-D, Han B, Zhang W, Jin X.-L, Yang L, Liu Z.-L. Synthesis 2006; 2831
• 11a Batey RA, Powell DA, Acton A, Lough AJ. Tetrahedron Lett. 2001; 42: 79359
• 11b Batey RA, Simoncic PD, Lin D, Smyj RP, Lough AJ. Chem. Commun. 1999; 651
• 11c Powell DA, Batey RA. Org. Lett. 2002; 4: 2913
• 11d Powell DA, Batey RA. Tetrahedron Lett. 2003; 44: 7569
• 11e Kumar A, Srivastava S, Gupta G. Tetrahedron Lett. 2010; 51: 517
• 11f Lin X.-F, Cui S.-L, Wang Y.-G. Tetrahedron Lett. 2006; 47: 4509
• 11g Zhang J, Li C.-J. J. Org. Chem. 2002; 67: 3969
• 12 Jia X.-D, Ren Y, Huo C.-D, Wang W.-J, Chen X.-N, Xu X.-L, Wang X.-C. Tetrahedron Lett. 2010; 51: 6779
• 13 Jia X.-D, Qing C, Huo C.-D, Peng F.-F, Wang X.-C. Tetrahedron Lett. 2012; 53: 7140
• 14 Jia X.-D, Peng F.-F, Qing C, Huo C.-D, Wang Y.-X, Wang X.-C. Tetrahedron Lett. 2013; 54: 4950
• 15 Jia X.-D, Ren Y, Huo C.-D, Wang W.-J, Chen X.-N, Fu Q, Wang X.-C. Chin. Chem. Lett. 2011; 22: 671
• 16 Jia X.-D, Wang X.-E, Yang C.-X, Huo C.-D, Wang W.-J, Ren Y, Wang X.-C. Org. Lett. 2010; 12: 732
• 17 Jia X.-D, Wang W.-J, Huo C.-D, Quan Z.-J, Wang X.-C. Synlett 2010; 2964

For oxidations of strained bonds, see:
• 18a Blancafort L, Adam W, González D, Olivucci M, Vreven T, Robb MA. J. Am. Chem. Soc. 1999; 121: 10583
• 18b Gerken JB, Wang SC, Preciado AB, Park YS, Nishiguchi G, Tantillo DJ, Little RD. J. Org. Chem. 2005; 70: 4598
• 18c Park YS, Wang SC, Tantillo DJ, Little RD. J. Org. Chem. 2007; 72: 4351
• 18d Park YS, Little RD. J. Org. Chem. 2008; 73: 6807
• 19a Jia X.-D, Chen X.-N, Wang X.-E, Huo C.-D, Wang W.-J, Ren Y, Wang X.-C. Eur. J. Org. Chem. 2011; 1627
• 19b Jia X.-D, Wang W.-J, Huo C.-D, Ren Y, Chen X.-N, Xu X.-L, Wang X.-C. Adv. Synth. Catal. 2011; 353: 315
• 20a Yasui S, Shioji K, Ohno A. Tetrahedron Lett. 1994; 35: 2695
• 20b Nakamura M, Miki M, Majima T. J. Chem. Soc., Perkin Trans. 2 2000; 1447
• 20c Shioji K, Ohno A, Yoshihara M. J. Org. Chem. 1995; 60: 2099
• 20d Pandey G, Hajra S, Ghorai MK. Tetrahedron Lett. 1994; 35: 7837
• 20e Yasui S, Tojo S, Majima T. J. Org. Chem. 2005; 70: 1276
• 20f Tojo S, Yasui S, Fujitsuka M, Majima T. J. Org. Chem. 2006; 71: 8227
• 21 For pioneering work on the cooperative use of TBPA+• and molecular oxygen, see: Nelsen SF, Akaba R. J. Am. Chem. Soc. 1981; 103: 2096
• 22 Jia X.-D, Peng F.-F, Qing C, Huo C.-D, Wang X.-C. Org. Lett. 2012; 14: 4030
• 23a Richter H, Mancheño OG. Org. Lett. 2011; 13: 6066
• 23b Rohlmann R, Stopka T, Richter H, Mancheño OG. J. Org. Chem. 2013; 78: 6050
• 24 Jia X.-D, Wang Y.-X, Peng F.-F, Huo C.-D, Yu L.-L, Wang X.-C. J. Org. Chem. 2013; 78: 9450
• 25 Wang Y.-X, Peng F.-F, Liu J, Huo C.-D, Wang X.-C, Jia X.-D. J. Org. Chem. 2015; 80: 609

For in situ generated radical-cation-promoted electron-transfer reactions, see:
• 26a Hasegawa E, Kakinuma K, Yanaki T, Komata S. Tetrahedron 2009; 65: 10876
• 26b Electron Transfer Reagents in Organic Synthesis . Vol. 52. Procter D, Flowers R. Tetrahedron Symposium-in-Print; 2009: 10725
• 27 Liu J, Wang Y.-X, Yu L.-L, Huo C.-D, Wang X.-C, Jia X.-D. Adv. Synth. Catal. 2014; 356: 3214

For selected examples of C–N bond cleavage, see:
• 28a Qian B, Xie P, Xie Y, Huang H.-M. Org. Lett. 2011; 13: 2580
• 28b Guo S, Qian B, Xie Y, Xia C, Huang H.-M. Org. Lett. 2011; 13: 522
• 28c Xie Y, Hu J, Wang Y, Xia C.-G, Huang H.-M. J. Am. Chem. Soc. 2012; 134: 20613
• 28d Xie Y, Hu J, Xie P, Qian B, Huang H.-M. J. Am. Chem. Soc. 2013; 135: 18327
• 28e Hu J.-H, Xie Y.-J, Huang H.-M. Angew. Chem. Int. Ed. 2014; 53: 7272
• 29 Huo C.-D, Wang C, Sun C.-G, Jia X.-D, Wang X.-C, Chang W.-J, Wu M.-X. Adv. Synth. Catal. 2013; 355: 1911
• 30 Jia X.-D, Wang Y.-X, Peng F.-F, Huo C.-D, Yu L.-L, Liu J, Wang X.-C. Adv. Synth. Catal. 2014; 356: 1210
• 31a Murahashi S.-I, Naota T, Yonemura K. J. Am. Chem. Soc. 1988; 110: 8256
• 31b Murahashi S, Naota T, Miyaguchi N, Nakato T. Tetrahedron Lett. 1992; 33: 6991
• 31c Murahashi S.-I, Komiya N, Terai H, Nakae T. J. Am. Chem. Soc. 2003; 125: 15312
• 31d Li Z, Li C.-J. J. Am. Chem. Soc. 2004; 126: 11810
• 31e Li Z, Bohle DS, Li C.-J. Proc. Natl. Acad. Sci. U.S.A. 2006; 103: 8928

For recent reviews, see:
• 32a Girard SA, Knauber T, Li C.-J. Angew. Chem. Int. Ed. 2014; 53: 74
• 32b Kozhushkov SI, Ackermann L. Chem. Sci. 2013; 4: 886
• 32c Shang X, Liu Z.-Q. Chem. Soc. Rev. 2013; 42: 3253
• 32d Liu C, Zhang H, Shi W, Lei A. Chem. Rev. 2011; 111: 1780
• 32e Yeung CS, Dong VM. Chem. Rev. 2011; 111: 1215
• 32f Sun C.-L, Li B.-J, Shi Z.-J. Chem. Rev. 2011; 111: 1293
• 32g Ashenhurst JA. Chem. Soc. Rev. 2010; 39: 540

For selected examples of radical-initiated sp³ C–H functionalizations, see:
• 33a Li Z, Xiao Y, Liu Z.-Q. Chem. Commun. 2015; 51: 9969
• 33b Li Z, Fan F, Yang J, Liu Z.-Q. Org. Lett. 2014; 16: 3396
• 33c Li Z, Zhang Y, Zhang L, Liu Z.-Q. Org. Lett. 2014; 16: 382
• 33d Cui Z, Shang X, Shao X.-F, Liu Z.-Q. Chem. Sci. 2012; 3: 2853

TBPA^+• was also able to promote the C–H functionalization of THIQs; this was studied by Huo, my co-worker. For examples, see:
• 34a Huo C.-D, Wu M.-X, Jia X.-D, Xie H.-S, Yuan Y, Tang J. J. Org. Chem. 2014; 79: 9860
• 34b Huo C.-D, Wang C, Wu M.-X, Jia X.-D, Wang X.-C, Yuan Y, Xie H.-S. Org. Biomol. Chem. 2014; 12: 3123
• 35 Liu J, Liu F, Zhu Y.-Z, Ma X.-G, Jia X.-D. Org. Lett. 2015; 17: 1409
• 36 Jia X.-D, Yu L.-L, Huo C.-D, Wang Y.-X, Liu J, Wang X.-C. Tetrahedron Lett. 2014; 55: 264