Nucleophilic Capture of Unsymmetrical Oxyallyl Cations with Indoles under Mild Brønsted Acid Catalysis

Abstract

We recently reported a new synthetic method in our laboratory concerning the control of regioselectivity in the addition of nucleophiles, such as indoles, to unsymmetrical oxyallyl cations. These reactive intermediates were readily generated upon ionization of the corresponding α-hydroxy enol ether precursors under catalytic, mild Brønsted acid. Results from our expansive scope of substrate studies revealed that regioselectivity in this reaction could be regulated upon protection of the oxygen atom in the oxyallyl cation moiety as well as modulation of the stereoelectronic effects in the participating α vs. α′ substituents.

Key words

Brønsted acid - nucleophilic addition - oxyallyl cation - indoles - α-functionalization

• References

• 1a Richter JM, Ishihara Y, Masuda T, Whitefield BW, Llamas T, Pohjakallio A, Baran PS. J. Am. Chem. Soc. 2008; 130: 17938
• 1b Baran PS, Maimone TJ, Richter JM. Nature (London, U.K.) 2007; 446: 404
• 1c Baran PS, Richter JM, Lin DW. Angew. Chem. Int. Ed. 2005; 44: 609
• 1d Baran PS, Richter JM. J. Am. Chem. Soc. 2005; 127: 15394
• 1e Baran PS, Richter JM. J. Am. Chem. Soc. 2004; 126: 7450
• 2a Frontier AJ, Collison C. Tetrahedron 2005; 61: 7577
• 2b Grant TN, Rieder CJ, West FG. Chem. Commun. 2009; 5676
• 2c Nakanishi W, West FG. Curr. Opin. Drug Discov. Dev. 2009; 12: 732
• 2d Shimada N, Stewart C, Tius MA. Tetrahedron 2011; 67: 5851
• 2e Vaidya T, Eisenberg R, Frontier AJ. ChemCatChem 2011; 3: 1531
• 3a Lohse AG, Hsung RP. Chem. Eur. J. 2011; 17: 3812
• 3b Harmata M. Chem. Commun. 2010; 46: 8904
• 3c Harmata M. Chem. Commun. 2010; 46: 8886
• 3d Foley DA, Maguire AR. Tetrahedron 2010; 66: 1131
• 3e Harmata M. Adv. Synth. Catal. 2006; 348: 2297
• 3f Battiste MA, Pelphrey PM, Wright DL. Chem. Eur. J. 2006; 12: 3438
• 3g Niess B, Hoffmann HM. R. Angew. Chem. Int. Ed. 2005; 44: 26
• 3h Hartung IV, Hoffmann HM. R. Angew. Chem. Int. Ed. 2004; 43: 1934
• 3i Harmata M, Rashatasakhon P. Tetrahedron 2003; 59: 2371
• 3j Harmata M. Acc. Chem. Res. 2001; 34: 595
• 4a Krenske EH, He SZ, Huang J, Du YF, Houk KN, Hsung RP. J. Am. Chem. Soc. 2013; 135: 5242
• 4b Li H, Hughes RP, Wu J. J. Am. Chem. Soc. 2014; 136: 6288
• 4c Li H, Wu J. Synthesis 2015; 47: 22
• 5a Fort AW. J. Am. Chem. Soc. 1962; 84: 2620
• 5b Freter K. Justus Liebigs Ann. Chem. 1978; 1357
• 5c Föhlisch B, Joachimi R. Chem. Ber. 1987; 120: 1951
• 5d Leitich J, Heise I. Eur. J. Org. Chem. 2001; 2707
• 5e Harmata M, Huang C, Rooshenas P, Schreiner PR. Angew. Chem. Int. Ed. 2008; 47: 8696
• 5f Tang Q, Chen X, Tiwari B, Chi YR. Org. Lett. 2012; 14: 1922
• 5g Wal MN. V, Dilger AK, MacMillan DW. C. Chem. Sci. 2013; 4: 3075
• 5h Luo J, Zhou H, Hu JW, Wang R, Tang Q. RSC Adv. 2014; 4: 17370
• 6a Ayala CE, Dange NS, Fronczek FR, Kartika R. Angew. Chem. Int. Ed. 2015; 54: 4641
• 6b Dange NS, Stepherson JR, Ayala CE, Fronczek FR, Kartika R. Chem. Sci. 2015; 6: 6312
• 7a Masuya K, Domon K, Tanino K, Kuwajima I. J. Am. Chem. Soc. 1998; 120: 1724
• 7b Lee JC, Cha JK. J. Am. Chem. Soc. 2001; 123: 3243
• 7c Lee JC, Cha JK. Tetrahedron 2000; 56: 10175
• 7d Chung WK, Lam SK, Lo B, Liu LL, Wong W.-T, Chiu P. J. Am. Chem. Soc. 2009; 131: 4556
• 8a Johnson F. Chem. Rev. 1968; 68: 375
• 8b Hoffmann RW. Chem. Rev. 1989; 89: 1841
• 9a Wu Y.-K, West FG. Org. Lett. 2014; 16: 2534
• 9b Wu Y.-K, Dunbar CR, McDonald R, Ferguson MJ, West FG. J. Am. Chem. Soc. 2014; 136: 14903
• 9c Kwon Y, Scadeng O, McDonald R, West FG. Chem. Commun. 2014; 50: 5558
• 9d Kwon Y, McDonald R, West FG. Angew. Chem. Int. Ed. 2013; 52: 8616
• 9e Wu Y.-K, McDonald R, West FG. Org. Lett. 2011; 13: 3584
• 9f Yaji K, Shindo M. Synlett 2009; 2524
• 9g Song D, Rostami A, West FG. J. Am. Chem. Soc. 2007; 129: 12019
• 9h Dhoro F, Kristensen TE, Stockmann V, Yap GP. A, Tius MA. J. Am. Chem. Soc. 2007; 129: 7256
• 9i White TD, West FG. Tetrahedron Lett. 2005; 46: 5629
• 9j Dhoro F, Tius MA. J. Am. Chem. Soc. 2005; 127: 12472
• 10a Liu Y, Han S.-J, Liu W.-B, Stoltz BM. Acc. Chem. Res. 2015; 48: 740
• 10b Reeves CM, Behenna DC, Stoltz BM. Org. Lett. 2014; 16: 2314
• 10c Zhang P, Le H, Kyne RE, Morken JP. J. Am. Chem. Soc. 2011; 133: 9716
• 10d Mohr JT, Behenna DC, Harned AM, Stoltz BM. Angew. Chem. Int. Ed. 2005; 44: 6924
• 10e Liu W.-B, Reeves CM, Virgil SC, Stoltz BM. J. Am. Chem. Soc. 2013; 135: 10626
• 10f Li J, Lee D. Chem. Sci. 2012; 3: 3296
• 10g Hong AY, Krout MR, Jensen T, Bennett NB, Harned AM, Stoltz BM. Angew. Chem. Int. Ed. 2011; 50: 2756
• 10h Behenna DC, Liu Y, Yurino T, Kim J, White DE, Virgil SC, Stoltz BM. Nat. Chem. 2012; 4: 130