Intermolecular Trapping of Alkoxyl Radicals with Alkenes: A New Route to Ether Synthesis

Abstract

Alkoxyl radicals are highly reactive species which rapidly react by hydrogen atom transfer (HAT) or β-fragmentation to afford a carbon-centered radical. We discuss herein how these RO· radicals can be efficiently trapped in an intermolecular manner by styrene derivatives when they are generated by photoredox catalysis from the corresponding N-alkoxypyridinium salts. This allows for the synthesis of valuable ethers with complete anti-Markovnikov regioselectivity.

1 Introduction

2 Anti-Markovnikov Alkoxylation of Alkenes: Background

3 Addition of Alkoxyl Radicals to Styrenes

4 Summary and Outlook

Key words

ether synthesis - photoredox catalysis - alkoxyl radicals - anti-Markovnikov addition - alkenes - N-alkoxypyridinium

• References

• 1a Elias H.-G. An Introduction to Polymer Science . Wiley-VCH; Weinheim: 1997
• 1b Müller F. Agrochemicals . Wiley-VCH; Weinheim: 1999
• 1c Li JJ, Johnson DS, Sliskovic DR, Roth BD. Contemporary Drug Synthesis . Wiley; Hoboken: 2004
• 1d Li JJ, Johnson DS. Modern Drug Synthesis . Wiley; Hoboken: 2010
• 1e Enthaler S, Company A. Chem. Soc. Rev. 2011; 40: 4912
• 1f Roughley SD, Jordan AM. J. Med. Chem. 2011; 54: 3451
• 1g Maligres PE, Li J, Krska SW, Schreier JD, Raheem IT. Angew. Chem. Int. Ed. 2012; 51: 9071
• 2a Williamson AW. J. Chem. Soc. 1852; 4: 229
• 2b Mitsunobu O. Synthesis 1981; 1
• 3a Hartwig JF. Angew. Chem. Int. Ed. 1998; 37: 2046
• 3b Muci AR, Buchwald SL. Top. Curr. Chem. 2002; 219: 131
• 3c Kunz K, Scholz U, Ganzer D. Synlett 2003; 2428
• 3d Ley SV, Thomas AW. Angew. Chem. Int. Ed. 2003; 42: 5400
• 4 Neuteufel RA, Arnold DR. J. Am. Chem. Soc. 1973; 95: 4080
• 5 Sutterer A, Moeller KD. J. Am. Chem. Soc. 2000; 122: 5636
• 6 Hamilton DS, Nicewicz DA. J. Am. Chem. Soc. 2012; 134: 18577
• 7 Weiser M, Hermann S, Penner A, Wagenknecht H.-A. Beilstein J. Org. Chem. 2015; 11: 568
• 8a Luo C, Bandar JS. J. Am. Chem. Soc. 2018; 140: 3547
• 8b Luo C, Bandar JS. Synlett 2018; 29: 2218

Examples of intermolecular addition of alkoxyl radicals onto alkenes:
• 9a Walling C, Thaler W. J. Am. Chem. Soc. 1961; 83: 3877
• 9b Inoue T, Koyama K, Matsuoka T, Tsutsumi S. Bull. Chem. Soc. Jpn. 1967; 40: 162
• 9c Elson IH, Mao SW, Kochi JK. J. Am. Chem. Soc. 1975; 97: 335
• 9d Wong PC, Griller D, Scaiano JC. J. Am. Chem. Soc. 1982; 104: 5106
• 9e Jones MJ, Moad G, Rizzardo E, Solomon DH. J. Org. Chem. 1989; 54: 1607

Selected reviews on photoredox catalysis:
• 10a Yoon TP, Ischay MA, Du J. Nat. Chem. 2010; 2: 527
• 10b Narayanam JM. R, Stephenson CR. J. Chem. Soc. Rev. 2011; 40: 102
• 10c Teplỳ F. Collect. Czech. Chem. Commun. 2011; 76: 859
• 10d Prier CK, Rankic DA, MacMillan DW. C. Chem. Rev. 2013; 113: 5322

For reviews on photoredox-catalyzed generation of alkoxyl radicals, see:
• 10e Zhang J, Chen YY. Acta Chim. Sin. 2017; 75: 41
• 10f Guo J.-J, Hu A, Zuo Z. Tetrahedron Lett. 2018; 59: 2103
• 10g Jia K, Chen YY. Chem. Commun. 2018; 54: 6105

For the formation of alkoxyl radicals under photoredox catalysis, see:
• 11a Zhang J, Li Y, Zhang FY, Hu CC, Chen YY. Angew. Chem. Int. Ed. 2016; 55: 1872
• 11b Jia KF, Zhang FY, Huang HC, Chen YY. J. Am. Chem. Soc. 2016; 138: 1514
• 11c Quint V, Morlet-Savary F, Lohier J.-F, Lalevée J, Gaumont A.-C, Lakhdar S. J. Am. Chem. Soc. 2016; 138: 7436
• 11d Yayla HG, Wang H, Tarantino KT, Orbe HS, Knowles RR. J. Am. Chem. Soc. 2016; 138: 10794
• 11e Wang C, Harms K, Meggers E. Angew. Chem. Int. Ed. 2016; 55: 13495
• 11f Guo JJ, Hu AH, Chen YL, Sun JF, Tang HM, Zuo ZW. Angew. Chem. Int. Ed. 2016; 55: 15319
• 11g Jia K, Pan Y, Chen YY. Angew. Chem. Int. Ed. 2017; 56: 2478
• 11h Zhang J, Li Y, Xu R, Chen YY. Angew. Chem. Int. Ed. 2017; 56: 12619
• 11i Kim I, Min M, Kang D, Kim K, Hong S. Org. Lett. 2017; 19: 1394
• 11j Hu A, Guo J.-J, Pan H, Tang H, Gao Z, Zuo Z. J. Am. Chem. Soc. 2018; 140: 1612
• 11k He Y.-T, Kang D, Kim I, Hong S. Green Chem. 2018; 20: 5209
• 11l He Y.-T, Won J, Kim J, Park B, Kim T, Baik M.-H, Hong S. Org. Chem. Front. 2018; 5: 2595
• 11m Wu X, Wang M, Huan L, Wang D, Wang J, Zhu C. Angew. Chem. Int. Ed. 2018; 57: 1640
• 11n Wu X, Zhang H, Tang N, Wu Z, Wang D, Ji M, Xu Y, Wang M, Zhu C. Nat. Commun. 2018; 9: 3343
• 11o Jelier B, Tripet PF, Pietrasiak E, Franzoni I, Jeschke G, Togni A. Angew. Chem. Int. Ed. 2018; 57: 13784
• 11p Kim I, Park B, Kang G, Kim J, Jung H, Lee H, Baik M.-H, Hong S. Angew. Chem. Int. Ed. 2018; 57: 15517
• 11q Li G.-X, Hu X, He G, Chen G. Chem. Sci. 2019; 10: 688
• 11r Bao X, Wang Q, Zhu J. Angew. Chem. Int. Ed. 2019; 58: 2139

For a recent review, see:
• 11s Capaldo L, Ravelli D. Chem. Commun. 2019; 55: 3029
• 12a Carboni A, Dagousset G, Magnier E, Masson G. Org. Lett. 2014; 16: 1240
• 12b Dagousset G, Carboni A, Magnier E, Masson G. Org. Lett. 2014; 16: 4340
• 12c Carboni A, Dagousset G, Magnier E, Masson G. Chem. Commun. 2014; 50: 14197
• 12d Carboni A, Dagousset G, Magnier E, Masson G. Synthesis 2015; 47: 2439
• 12e Jarrige L, Carboni A, Dagousset G, Levitre G, Magnier E, Masson G. Org. Lett. 2016; 18: 2906
• 12f Dagousset G, Simon C, Anselmi E, Tuccio B, Billard T, Magnier E. Chem. Eur. J. 2017; 23: 4282
• 12g Daniel M, Dagousset G, Diter P, Klein P.-A, Tuccio B, Goncalves A.-M, Masson G, Magnier E. Angew. Chem. Int. Ed. 2017; 56: 3997
• 13 Barthelemy A.-L, Tuccio B, Magnier E, Dagousset G. Angew. Chem. Int. Ed. 2018; 57: 13790
• 14 Walton JC, Studer A. Acc. Chem. Res. 2005; 38: 794

Selected reviews:
• 15a Knowles JP, Elliott LD, Booker-Milburn KI. Beilstein J. Org. Chem. 2012; 8: 2025
• 15b Su Y, Straathof NJ. W, Hessel V, Noël T. Chem. Eur. J. 2014; 20: 10562
• 15c Garlets ZJ, Nguyen JD, Stephenson CR. J. Isr. J. Chem. 2014; 54: 351
• 15d Plutschack MB, Correia CA, Seeberger PH, Gilmore K. Top. Organomet. Chem. 2016; 57: 43
• 15e Cambié D, Bottecchia C, Straathof NJ. W, Hessel V, Noël T. Chem. Rev. 2016; 116: 10276
• 16 In the case of 4-cyano-N-phenethoxypyridinium salt β-fragmentation was mainly observed because it led to the formation of a benzylic radical, which is much stable than other primary C-centered radicals. For more details see ref.¹³
• 17a Katriizky AR, Lunt E. Tetrahedron 1969; 25: 4291
• 17b Sliwa H, Randria-Raharimanana C. Tetrahedron Lett. 1986; 27: 349
• 17c Sliwa H, Ouattara L. J. Heterocycl. Chem. 1987; 24: 1617
• 17d Sliwa H, Randria-Raharimanana C, Cordonnier G. J. Heterocycl. Chem. 1991; 28: 1127
• 17e Karki SB, Dinnocenzo JP, Jones JP, Korzekwa KR. J. Am. Chem. Soc. 1995; 117: 3657

Selected examples:
• 18a Barba I, Chinchilla R, Gomez C. J. Org. Chem. 1990; 55: 3270
• 18b Schultz MJ, Sigman MS. J. Am. Chem. Soc. 2006; 128: 1460
• 18c Silva JrL. F, Craveiro MV, Gambardella MT. P. Synthesis 2007; 3851
• 19a Buettner G. Free Radic. Biol. Med. 1987; 3: 259 and references therein
• 19b Adam W, Hartung J, Okamoto H, Marquardt S, Nau WM, Pischel U, Saha-Moller CR, Spehar K. J. Org. Chem. 2002; 67: 6041
• 20 Gould IR, Shukla D, Giesen D, Farid S. Helv. Chim. Acta 2001; 84: 2796