Cobalt-Catalyzed Chelation-Assisted Alkylation of Arenes with Primary and Secondary Alkyl Halides

Abstract

Cobalt–N-heterocyclic carbene catalytic systems have been developed for chelation-assisted ortho-alkylation of aromatic compounds with alkyl halides. Aryl imines can be selectively monoalkylated at room temperature by various primary or secondary alkyl chlorides or bromides. The catalytic system can also be applied to 2-arylpyridine derivatives, which in the absence of steric hindrance are amenable to dialkylation by an excess of the alkyl halide. Mechanistic experiments, including reactions of stereochemical probes and radical clocks, indicate that the reaction involves single-electron transfer from the cobalt center to the alkyl halide to form the corresponding alkyl radical, which has a finite lifetime before it undergoes C–C bond formation.

Key words

functionalization - catalysis - cobalt - alkylations - alkyl halides - radical reaction

• References

• 1 Murai S, Kakiuchi F, Sekine S, Tanaka Y, Kamatani A, Sonoda M, Chatani N. Nature 1993; 366: 529

For recent reviews, see:
• 2a Kakiuchi F, Kochi T. Synthesis 2008; 3013
• 2b Colby DA, Bergman RG, Ellman JA. Chem. Rev. 2010; 110: 624
• 2c Ackermann L. Chem. Rev. 2011; 111: 1315
• 2d Arockiam PB, Bruneau C, Dixneuf PH. Chem. Rev. 2012; 112: 5879

For recent examples, see:
• 3a Kakiuchi F, Kochi T, Mizushima E, Murai S. J. Am. Chem. Soc. 2010; 132: 17741
• 3b Ilies L, Chen Q, Zeng X, Nakamura E. J. Am. Chem. Soc. 2011; 133: 5221
• 3c Gao K, Yoshikai N. Angew. Chem. Int. Ed. 2011; 50: 6888
• 3d Schinkel M, Marek I, Ackermann L. Angew. Chem. Int. Ed. 2013; 52: 3977
• 3e Rouquet G, Chatani N. Chem. Sci. 2013; 4: 2201

For branched-selective reaction with styrene derivatives, see:
• 4a Uchimaru Y. Chem. Commun. 1999; 1133
• 4b Gao K, Yoshikai N. J. Am. Chem. Soc. 2011; 133: 400
• 4c Pan S, Ryu N, Shibata T. J. Am. Chem. Soc. 2012; 134: 17474
• 4d Lee P.-S, Yoshikai N. Angew. Chem. Int. Ed. 2013; 52: 1240
• 4e Dong J, Lee P.-S, Yoshikai N. Chem. Lett. 2013; 42: 1140

For Markovnikov-selective reaction of phenol derivatives with alkyl olefins, see:
• 5a Lewis LN, Smith JF. J. Am. Chem. Soc. 1986; 108: 2728
• 5b Dorta R, Togni A. Chem. Commun. 2003; 760
• 5c Kuninobu Y, Matsuki T, Takai K. J. Am. Chem. Soc. 2009; 131: 9914
• 5d Oyamada J, Hou Z. Angew. Chem. Int. Ed. 2012; 51: 12828
• 6 Ackermann L. Chem. Commun. 2010; 46: 4866
• 7a Ackermann L, Novák P, Vicente R, Hofmann N. Angew. Chem. Int. Ed. 2009; 48: 6045
• 7b Zhang Y.-H, Shi B.-F, Yu J.-Q. Angew. Chem. Int. Ed. 2009; 48: 6097
• 7c Shabashov D, Daugulis O. J. Am. Chem. Soc. 2010; 132: 3965
• 7d Chen Q, Ilies L, Nakamura E. J. Am. Chem. Soc. 2011; 133: 428
• 7e Ackermann L, Hofmann N, Vicente R. Org. Lett. 2011; 13: 1875
• 7f Zhao YS, Chen G. Org. Lett. 2011; 13: 4850
• 7g Aihara Y, Chatani N. J. Am. Chem. Soc. 2013; 135: 5308
• 7h Song W, Lackner S, Ackermann L. Angew. Chem. Int. Ed. 2014; 53: 2477

For examples of nondirected alkylation of heteroarenes with secondary alkyl halides, see:
• 8a Xiao B, Liu Z.-J, Liu L, Fu Y. J. Am. Chem. Soc. 2013; 135: 616
• 8b Ren P, Salihu I, Scopelliti R, Hu X. Org. Lett. 2012; 14: 1748
• 9 For meta-selective alkylation with secondary alkyl halides through cyclometalation process, see: Hofmann N, Ackermann L. J. Am. Chem. Soc. 2013; 135: 5877

For ortho-alkylations using different sources of secondary alkyl groups, see:
• 10a Lee D.-H, Kwon K.-H, Yi CS. J. Am. Chem. Soc. 2012; 134: 7325
• 10b Deng G.-J, Zhao L, Li C.-J. Angew. Chem. Int. Ed. 2008; 47: 6278
• 11a Yoshikai N. Synlett 2011; 1047
• 11b Gao K, Yoshikai N. Acc. Chem. Res. 2014; 47: 1208
• 12 Gao K, Yoshikai N. J. Am. Chem. Soc. 2013; 135: 9279
• 13 Gao K, Yoshikai N. Chem. Commun. 2012; 48: 4305
• 14 Gao K, Lee P.-S, Long C, Yoshikai N. Org. Lett. 2012; 14: 4234
• 15 Song W, Ackermann L. Angew. Chem. Int. Ed. 2012; 51: 8251
• 16 Punji B, Song WF, Shevchenko GA, Ackermann L. Chem. Eur. J. 2013; 19: 10605
• 17 Yang S, Li Z, Han X, He C. Angew. Chem. Int. Ed. 2009; 48: 3999
• 18 Lee P.-S, Fujita T, Yoshikai N. J. Am. Chem. Soc. 2011; 133: 17283
• 19 The use of smaller amounts of Me(CH₂)₇Cl (1.5 equiv) and t-BuCH₂MgBr (2 equiv) did not effect full conversion of the monoalkylation product formed in the first step, thereby giving the desired product in a lower yield (~30%).
• 20a Ohmiya H, Wakabayashi K, Yorimitsu H, Oshima K. Tetrahedron 2006; 62: 2207
• 20b Ohmiya H, Yorimitsu H, Oshima K. J. Am. Chem. Soc. 2006; 128: 1886
• 20c Cahiez G, Chaboche C, Duplais C, Moyeux A. Org. Lett. 2009; 11: 277

For reviews on cobalt-catalyzed cross-coupling reactions, see:
• 21a Cahiez G, Moyeux A. Chem. Rev. 2010; 110: 1435
• 21b Hess W, Treutwein J, Hilt G. Synthesis 2008; 3537
• 21c Gosmini C, Bégouin JM, Moncomble A. Chem. Commun. 2008; 3221
• 21d Yorimitsu H, Oshima K. Pure Appl. Chem. 2006; 78: 441
• 22 Newcomb M. Tetrahedron 1993; 49: 1151
• 23 The higher yield reported in our earlier communication (3aaf/3aaf' with 97% yield and an 88:12 ratio; see ref. 12) could not be reproduced in this study.
• 24 Klein H.-F, Camadanli S, Beck R, Leukel D, Flörke U. Angew. Chem. Int. Ed. 2005; 44: 975
• 25 Wakabayashi K, Yorimitsu H, Oshima K. J. Am. Chem. Soc. 2001; 123: 5374
• 26 Huynh HV, Han Y, Ho JH. H, Tan GK. Organometallics 2006; 25: 3267
• 27a Mršić N, Minnaard AJ, Feringa BL, de Vries JG. J. Am. Chem. Soc. 2009; 131: 8358
• 27b Gautier F.-M, Jones S, Martin SJ. Org. Biomol. Chem. 2009; 7: 229
• 28 Mongin F, Mojovic L, Guillamet B, Trécourt F, Quéguiner G. J. Org. Chem. 2002; 67: 8991
• 29 Yasuda M, Yamasaki S, Onishi Y, Baba A. J. Am. Chem. Soc. 2004; 126: 7186
• 30a Jaegar DA, Ward MD, Martin CA. Tetrahedron 1984; 40: 2691
• 30b Hochstein FA, Brown WG. J. Am. Chem. Soc. 1948; 70: 3484
• 30c Guthrie RW, Kierstead RW, Mullin JG, Tilley JW. US 4927838, 1990
• 31 Roberts BP, Steel AJ. J. Chem. Soc., Perkin Trans. 2 1994; 2411
• 32 Cahiez G, Gager O, Moyeux A, Delacroix T. Adv. Synth. Catal. 2012; 354: 1519
• 33 Kakiuchi F, Sekine S, Tanaka Y, Kamatani A, Sonoda M, Chatani N, Murai S. Bull. Chem. Soc. Jpn. 1995; 68: 62
• 34 Savarin CG, Grisé C, Murry JA, Reamer RA, Hughes DL. Org. Lett. 2007; 9: 981
• 35 Cahiez G, Luart D, Lecomte F. Org. Lett. 2004; 6: 4395