Enamide Derivatives: Versatile Building Blocks for Highly Functionalized α,β-Substituted Amines

Guillaume Bernadat; Geraldine Masson

doi:10.1055/s-0034-1379166

Synlett, Table of Contents

Synlett 2014; 25(20): 2842-2867
DOI: 10.1055/s-0034-1379166

account

Enamide Derivatives: Versatile Building Blocks for Highly Functionalized α,β-Substituted Amines

Guillaume Bernadat

Centre de Recherche de Gif, Institut de Chimie des Substances Naturelles CNRS, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France Fax: +33(1)69077247 Email: Geraldine.Masson@cnrs.fr

,

Geraldine Masson*

Centre de Recherche de Gif, Institut de Chimie des Substances Naturelles CNRS, 1 Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, France Fax: +33(1)69077247 Email: Geraldine.Masson@cnrs.fr

› Author Affiliations

Abstract

All articles of this category

Abstract

As demonstrated by earlier successes with enamines, nitrogen-activated C=C double bonds have considerable potential for use in the construction of various nitrogen-containing products. To expand the applications of this class of substrates, we focused on studying the reactivity of enamides and enecarbamates as promising representatives. Starting from the well-known Povarov reaction, we gradually developed other cycloaddition reactions and, more generally, an extended range of methods for α,β-difunctionalization. Our most recent work, which involves radical processes, has contributed to a significant increase in the diversity of scaffolds accessible from these nitrogenous substrates and is potentially applicable to various natural and bioactive synthetic targets.

1 Introduction

2 General Design

3 Asymmetric Brønsted Acid-Catalyzed α,β-Difunctionalization of Enamides

3.1 Intramolecular α,β-Difunctionalization of Enamides Through Cycloaddition Reactions

3.1.1 Povarov Reactions

3.1.2 Diels–Alder Reactions of 1-Azadienes

3.2 Intermolecular α,β-Difunctionalization of Enamides

3.2.1 Mannich Reactions

3.2.2 Addition to Azo Compounds

3.2.3 Halogenation Reactions

4 Radical Tandem Difunctionalization: β-Alkylation Followed by α-Functionalization of Enamides

4.1 Photoredox-Mediated Tandem α,β-Difunctionalization of Enamides

4.1.1 Oxyalkylation

4.1.2 Oxy-, Amino- and Carbotrifluoromethylation

4.2 Single-Electron Transfer-Mediated Tandem α,β-Difunctionalization of Enamides

5 Conclusion

Key words

enamides - enecarbamates - chiral phosphoric acid - photoredox catalysis - radical reaction

Full Text

References

References

1a For a recent review on chiral amine synthesis, see Chiral Amine Synthesis. Methods, Developments and Applications, Nugent T. C. Wiley-VCH; Weinheim: 2010
1b Nugent TC, El-Shazly M. Adv. Synth. Catal. 2010; 352: 753

For selected reviews on difunctionalization of alkenes, see:

2a Muñiz K. Chem. Soc. Rev. 2004; 33: 166
2b Wolfe JP. Synlett 2008; 2913
2c Jensen KH, Sigman MS. Org. Biomol. Chem. 2008; 6: 4083
2d Cardona F, Goti A. Nat. Chem. 2009; 1: 269
2e McDonald RI, Liu G, Stahl SS. Chem. Rev. 2011; 111: 2981
2f Wolfe JP. Angew. Chem. Int. Ed. 2012; 51: 10224
2g Xue Q, Xie J, Xu P, Hu K, Cheng Y, Zhu C. ACS Catal. 2013; 3: 1365

3 For tandem vicinal difunctionalizations involving cyclic enamides, see: Maryanoff BE, Zhang H.-C, Cohen JH. Turchi I. J, Maryanoff CA. Chem. Rev. 2004; 104: 1431

For monographs on asymmetric organocatalysis, see:

4a Enantioselective Organocatalysis: Dalko P. I. Wiley-VCH; Weinheim: 2006
4b Special Issue: Asymmetric Organocatalysis, Top. Curr. Chem. 2009; 291: 1

For selected reviews on enamine catalysis, see:

4c Mukherjee S, Yang JW, Hoffmann S, List B. Chem. Rev. 2007; 107: 5471
4d Enders D, Grondal C, Hüttl MR. M. Angew. Chem. Int. Ed. 2007; 46: 1570
4e MacMillan DW. C. Nature 2008; 455: 304
4f Melchiorre P, Marigo M, Carlone A, Bartoli G. Angew. Chem. Int. Ed. 2008; 47: 6138
4g Bertelsen S, Jørgensen KA. Chem. Soc. Rev. 2009; 38: 2178
4h Jensen KL, Dickmeiss G, Jiang H, Albrecht Ł, Jørgensen KA. Acc. Chem. Res. 2012; 45: 248
4i Meninno S, Lattanzi A. Chem. Commun. 2013; 49: 3821

5a Matsubara R, Kobayashi S. Acc. Chem. Res. 2008; 41: 292
5b Carbery DR. Org. Biomol. Chem. 2008; 6: 3455
5c Gopalaiah K, Kagan HB. Chem. Rev. 2011; 111: 4599

6 Stevens RV. Acc. Chem. Res. 1977; 10: 193

7a Eberson L, Malmberg M, Nyberg K. Acta Chem. Scand., Ser. B 1984; 38: 391
7b Meth-Cohn O, Westwood KT. J. Chem. Soc., Perkin Trans. 1 1984; 1173
7c Shono T, Matsumura Y, Tsubata K, Suihara Y, Yamane S, Kanazawa T, Aoki T. J. Am. Chem. Soc. 1982; 104: 6697

For selected examples, see:

8a Matsubara R, Nakamura Y, Kobayashi S. Angew. Chem. Int. Ed. 2004; 43: 1679
8b Matsubara R, Nakamura Y, Kobayashi S. Angew. Chem. Int. Ed. 2004; 43: 3258
8c Fossey JS, Matsubara R, Vital P, Kobayashi S. Org. Biomol. Chem. 2005; 3: 2910
8d Matsubara R, Kawai N, Kobayashi S. Angew. Chem. Int. Ed. 2006; 45: 3814
8e Kiyohara H, Matsubara R, Kobayashi S. Org. Lett. 2006; 8: 5333
8f Matsubara R, Doko T, Uetake R, Kobayashi S. Angew. Chem. Int. Ed. 2007; 46: 3047
8g Berthiol F, Matsubara R, Kawai N, Kobayashi S. Angew. Chem. Int. Ed. 2007; 46: 7803

For other selected examples, see:

9a Terada M, Machioka K, Sorimachi K. Angew. Chem. Int. Ed. 2006; 45: 2254
9b Terada K, Machioka K, Sorimachi K. J. Am. Chem. Soc. 2007; 129: 10336
9c Terada M, Soga K, Momiyama N. Angew. Chem. Int. Ed. 2008; 47: 4122
9d Zu L, Xie H, Li H, Wang J, Yu X, Wang W. Chem. Eur. J. 2008; 14: 6333
9e Terada M, Machioka K, Sorimachi K. Angew. Chem. Int. Ed. 2009; 48: 2553
9f Yang L, Wang D.-X, Huang Z.-T, Wang MX. J. Am. Chem. Soc. 2009; 131: 10390
9g Hayashi Y, Gotoh H, Masui R, Ishikawa H. Angew. Chem. Int. Ed. 2010; 47: 4012

For vicinal difunctionalization of enamides, see:

10a Seebach D, Stucky G, Pfammatter E. Chem. Ber. 1989; 122: 2377
10b Wieber GM, Hegedus LS, Åkermark B, Michalson ET. J. Org. Chem. 1989; 54: 4649
10c Masters JJ, Hegedus LS, Tamariz J. J. Org. Chem. 1991; 56: 5666
10d Harrison T, Dake GR. Org. Lett. 2004; 6: 5023
10e Matos MN, Afonso CA. M, Batey RA. Tetrahedron 2005; 61: 1221

For recent reviews on catalysis by chiral phosphoric acids, see:

11a Akiyama T, Itoh J, Fuchibe K. Adv. Synth. Catal. 2006; 348: 999
11b Akiyama T. Chem. Rev. 2007; 107: 5744
11c Terada M. Chem. Commun. 2008; 4097
11d Terada M. Synthesis 2010; 1929
11e Zamfir A, Schenker S, Freund M, Tsogoeva SB. Org. Biomol. Chem. 2010; 8: 5262
11f Kampen D, Reisinger CM, List B. Top. Curr. Chem. 2010; 291: 395
11g Terada M. Bull. Chem. Soc. Jpn. 2010; 83: 101
11h Rueping M, Kuenkel A, Atodiresei I. Chem. Soc. Rev. 2011; 40: 4539

12 Akiyama T, Itoh J, Yokota K, Fuchibe K. Angew. Chem. Int. Ed. 2004; 43: 1566
13 Uraguchi D, Terada M. J. Am. Chem. Soc. 2004; 126: 5356
14 Akiyama T. US 20060276329, 2006

15a Buonora P, Olsen J.-C, Oh T. Tetrahedron 2001; 57: 6099
15b Heintzelman GR, Meigh IR, Mahajan YR, Weinreb SM. Org. React. (N. Y.) 2005; 65: 141
15c Rowland GB, Rowland EB, Zhang Q, Antilla JC. Curr. Org. Chem. 2006; 10: 981
15d Kouznetsov VV. Tetrahedron 2009; 65: 2721
15e Girling PR, Kiyoi T, Whiting A. Org. Biomol. Chem. 2011; 9: 3105
15f Jiang XX, Wang R. Chem. Rev. 2013; 113: 5515
15g Masson G, Lalli C, Benohoud M, Dagousset G. Chem. Soc. Rev. 2013; 42: 902

16a Povarov LS. Russ. Chem. Rev 1967; 36: 656
16b Glushkov VA, Tolstikov AG. Russ. Chem. Rev. 2008; 77: 137
16c Bello D, Ramόn R, Lavilla R. Curr. Org. Chem. 2010; 14: 332
16d Fochi M, Caruana L, Bernardi L. Synthesis 2014; 46: 135

17a Bazin M, Kuhn C. J. Comb. Chem. 2005; 7: 302 ; and references cited therein
17b Sridharan V, Suryavanshi PA, Menendez JC. Chem. Rev. 2011; 111: 7157

For the first examples of Povarov reactions using eneamide derivatives, see:

17c Leeson PD, Carling RW, Moore KW, Moseley AM, Smith JD, Stevenson G, Chan T, Baker R, Foster AC, Grimwood S, Kemp JA, Marshall GR, Hoogsteen K. J. Med. Chem. 1992; 35: 1954
17d Hadden M, Stevenson PJ. Tetrahedron Lett. 1999; 40: 1215
17e Batey RA. Simoncic P. D. Lin D, Smyj RP, Lough AJ. Chem. Commun. 1999; 651

18a Witherup KM, Ransom RW, Graham AC, Bernard MJ, Salvatore AM, Lumma WC, Anderson PS, Pitzenberger SM, Varga SL. J. Am. Chem. Soc. 1995; 117: 6682
18b Gentry AH, Cook KJ. Ethnopharmacol. 1984; 11: 337
18c Blakeney JS, Reid RC, Le GT, Fairlie DP. Chem. Rev. 2007; 107: 2960

19 Carling RW, Leeson PD, Moseley AM, Smith JD, Saywell K, Tricklebank MD, Kemp JA, Marshall GR, Foster AC, Grimwood S. Bioorg. Med. Chem. Lett. 1993; 3: 65

20a Damon DB, Dugger RW. EP 1125929, 2001 ; US 6313142, 2001
20b Damon DB, Dugger RW, Scott RW. S 6689897, 2004
20c Damon DB, Dugger RW, Magnus-Aryitey G, Ruggeri RB, Wester RT, Tu M, Abramov Y. Org. Process Res. Dev. 2006; 10: 464
20d Damon DB. Dugger R. W, Hubbs SE, Scott JM, Scott RW. Org. Process Res. Dev. 2006; 10: 472
20e Guinó M, Phua PH, Caille J.-C, Hii KK. J. Org. Chem. 2007; 72: 6290

21a Ishitani H, Kobayashi S. Tetrahedron Lett. 1996; 37: 7357
21b Sundararajan G, Prabagaran N, Varghese B. Org. Lett. 2001; 3: 1973
21c Akiyama T, Morita H, Fuchibe K. J. Am. Chem. Soc. 2006; 128: 13070

22 Liu H, Dagousset G, Masson G, Retailleau P, Zhu J. J. Am. Chem. Soc. 2009; 131: 4598
23 Dagousset G, Zhu J, Masson G. J. Am. Chem. Soc. 2011; 133: 14804

24a De Rosa M, Issac RP, Houghton G. Tetrahedron Lett. 1995; 36: 9261
24b Cirrincione G, Almerico AM, Diana P, Barraja P, Mingoia F, Grimaudo S, Dattolo G, Aiello E. J. Heterocycl. Chem. 1996; 33: 161
24c De Rosa M, Issac RP, Marquez M, Orozco M, Luque FJ, Timken MD. J. Chem. Soc., Perkin Trans. 2 1999; 1433

For examples of enantioselective processes combining a chiral phosphoric acid and a Pd catalyst, see:

25a Mukherjee S, List B. J. Am. Chem. Soc. 2007; 129: 11336
25b Chai Z, Rainey TJ. J. Am. Chem. Soc. 2012; 134: 3615

26 Brioche J, Courant T, Alcaraz L, Stocks M, Furber M, Zhu J, Masson G. Adv. Synth. Catal. 2014; 356: 1719
27 Batey RA, Powell DA. Chem. Commun. 2001; 2362
28 Dagousset G, Retailleau P, Masson G, Zhu J. Chem. Eur. J. 2012; 18: 5869

For examples with enamides and enecarbamates, see:

29a Xu H, Zuend SJ, Woll MG, Tao Y, Jacobsen EN. Science 2010; 327: 986
29b Wang C, Han ZY, Luo HW, Gong LZ. Org. Lett. 2010; 12: 2266
29c Lin JH, Zong GQ, Du RB, Xiao JC, Liu SB. Chem. Commun. 2012; 48: 7738
29d Min C, Mittal N, Sun DX, Seidel D. Angew. Chem. Int. Ed. 2013; 52: 14084
29e Caruana L, Fochi M, Ranieri S, Mazzanti A, Bernardi L. Chem. Commun. 2013; 49: 880
29f Huang D, Xu F, Chen T, Wang Y, Lin X. RSC Adv. 2013; 3: 573

For examples with enamines, see:

29g Chen ZL, Wang BL, Wang ZB, Zhu GY, Sun JW. Angew. Chem. Int. Ed. 2013; 52: 2027
29h Luo CS, Huang Y. J. Am. Chem. Soc. 2013; 135: 8193

30 Bergonzini G, Gramigna L, Mazzanti A, Fochi M, Bernardi L, Ricci A. Chem. Commun. 2010; 46: 327

31a He L, Bekkaye M, Retailleau P, Masson G. Org. Lett. 2012; 14: 3158
31b Shi F, Xing G.-J, Tao Z.-L, Luo S.-W, Tu S.-J, Gong L.-Z. J. Org. Chem. 2012; 77: 6970
31c Shi F, Xing G.-J, Zhu R.-Y, Tan W, Tu S. Org. Lett. 2013; 15: 128

For a concerted mechanism, see:

32a Beifuss U, Ledderhose S, Ondrus V. ARKIVOC 2005; (v): 147
32b Stevenson PJ, Nieuwenhuyzen M, Osborne D. ARKIVOC 2007; (xi): 12

See also:

32c McCarrick MA, Wu Y.-D, Houk KN. J. Org. Chem. 1993; 58: 3330
32d Whiting A, Windsor CM. Tetrahedron 1998; 54: 6035

For a stepwise mechanism, see:

33a Kobayashi S, Ishitani H, Nakagawa S. Synthesis 1995; 1195
33b Hermitage S, Jay DA, Whiting A. Tetrahedron Lett. 2002; 43: 9633
33c Stevenson PJ, Graham I. ARKIVOC 2003; (vii): 139
33d Carranco I, Díaz JL, Jiménez O, Lavilla R. Tetrahedron Lett. 2003; 44: 8849
33e Sridharan V, Avendaño C, Menéndez JC. Synthesis 2008; 1039
33f Alves MJ, Azoia NG, Fortes AG. Tetrahedron 2007; 63: 727
33g Shindoh N, Tokuyama H, Takemoto Y, Takasu K. J. Org. Chem. 2008; 73: 7451

For examples of interrupted Povarov reactions, see:

34a Anniyappan M, Muralidharan D, Perumal PT. Tetrahedron 2002; 58: 10301
34b Yadav JS, Subba Reddy BV, Madhuri C, Sabitha G, Jagannadh B, Kiran Kumar S, Kunwar AC. Tetrahedron Lett. 2001; 42: 6381
34c Jiménez O, de la Rosa G, Lavilla R. Angew. Chem. Int. Ed. 2005; 44: 6521
34d Isambert N, Cruz M, Arévalo MJ, Gómez E, Lavilla R. Org. Lett. 2007; 9: 4199
34e Wang J, Xu X.-F, Lin X.-F, Wang Y.-G. Tetrahedron Lett. 2008; 49: 5208
34f Bernardi L, Comes-Franchini M, Fochi M, Leo V, Mazzanti A, Ricci A. Adv. Synth. Catal. 2010; 352: 3399
34g Rueping M, Lin M.-Y. Chem. Eur. J. 2010; 16: 4169
34h Zhang Y, Dong S, Liu X, Xie M, Zhu Y, Lin L, Feng X. Chem. Eur. J. 2011; 17: 13684
34i Preciado S, Vicente-García E, Llabrés S, Luque FJ, Lavilla R. Angew. Chem. Int. Ed. 2012; 51: 6874
34j Wang G, Li B, Lou Q, Li Z, Meng X. Adv. Synth. Catal. 2013; 355: 303
34k Wu H, He Y.-P, Gong L.-Z. Org. Lett. 2013; 15: 460
34l Cala L, Mendoza A, Fañanás FJ, Rodríguez F. Chem. Commun. 2013; 49: 2715

35 Simón L, Goodman JM. J. Org. Chem. 2011; 76: 1775

36a Michael JP In The Alkaloids: Chemistry and Biology . Vol. 55. Cordell GA. Academic Press; San Diego: 2001: 91
36b Bailey PD, Millwood PA, Smith PD. Chem. Commun. 1998; 633
36c Lillelund VH, Jensen HH, Liang XF, Bols M. Chem. Rev. 2002; 102: 515
36d Weintraub PM, Sabol JS, Kane JM, Borcherding DR. Tetrahedron 2003; 59: 2953
36e Buffat MG. P. Tetrahedron 2004; 60: 1701
36f Felpin F.-X, Lebreton J. Curr. Org. Synth. 2004; 1: 83
36g Zanatta N, Fernandes da Silva L, Nachtigall FM, Coelho HS, Amaral SS, Flores AF. C, Bonacorso HG, Martins MA. P. Eur. J. Org. Chem. 2009; 1435 ; and references cited therein
36h Huang X, Zhang A, Chen D, Jia Z, Li X. Bioorg. Med. Chem. Lett. 2010; 20: 2859

For an example of a catalytic enantioselective inverse electron-demand aza-Diels–Alder (IEDADA) reaction using 1-azadienes and chiral Lewis acids, see:

37a Esquivias J, Gómez Arrayás R, Carretero JC. J. Am. Chem. Soc. 2007; 129: 1480

For examples of catalytic enantioselective IEDADA reactions using 1-azadienes and chiral covalent organocatalysts, see:

37b He M, Struble JR, Bode JW. J. Am. Chem. Soc. 2006; 128: 8418
37c Li J.-L, Liu T.-Y, Chen Y.-C. Acc. Chem. Res. 2012; 45: 1491
37d Li Q.-Z, Ma L, Dong L, Chen Y.-C. ChemCatChem 2012; 4: 1139
37e Simal C, Lebl T, Slawin AM. Z, Smith AD. Angew. Chem. Int. Ed. 2012; 51: 3653
37f Jiang X, Shi X, Wang S, Sun T, Cao Y, Wang R. Angew. Chem. Int. Ed. 2012; 51: 2084
37g Deng Y, Liu L, Sarkisian RG, Wheeler K, Wang H, Xu Z. Angew. Chem. Int. Ed. 2013; 52: 3663
37h Jian T.-Y, Shao P.-L, Ye S. Chem. Commun. 2011; 47: 2381
37i Hu P, Hu J, Jiao J, Tong X. Angew. Chem. Int. Ed. 2013; 52: 5319
37j Wan J.-P, Loh CC. J, Pan F, Enders D. Chem. Commun. 2012; 48: 10049

38a Nishimura Y, Satoh T, Adachi H, Kondo S, Takeuchi T, Azetaka M, Fukuyasu H, Lizuka Y. J. Med. Chem. 1997; 40: 2626
38b Knapp S, Zhao D. Org. Lett. 2000; 2: 4037
38c Shitara E, Nishimura Y, Nerome K, Hiramoto Y, Takeuchi T. Org. Lett. 2000; 2: 3837

39 He L, Laurent G, Retailleau P, Folléas B, Brayer J.-L, Masson G. Angew. Chem. Int. Ed. 2013; 52: 11088
40 Whitesell JK, Whitesell MA. Synthesis 1983; 517

41a Gonzalez J, Houk KN. J. Org. Chem. 1992; 57: 3031
41b Domingo LR. Tetrahedron 2002; 58: 3765
41c Parr RG, von Szentpály L, Liu S. J. Am. Chem. Soc. 1999; 121: 1922

42 For stepwise mechanisms, see: Domingo LR, Sáez JA. Org. Biomol. Chem. 2009; 7: 3576

For examples of bioactive natural 1,3-amines, see:

43a Jahn T, König GM, Wright AD. Tetrahedron Lett. 1997; 38: 3883
43b Franklin AS, Ly SK, Mackin GH, Overman LE, Shaka AJ. J. Org. Chem. 1999; 64: 1512
43c Cohen F, Overman LE. J. Am. Chem. Soc. 2001; 123: 10782
43d When PM, Du Bois J. J. Am. Chem. Soc. 2002; 124: 12950

For examples of bioactive 1,3-amines of non-natural origin, see:

43e Bergeron RJ, Feng Y, Weimar WR, McManis JS, Dimova H, Porter C, Raisler B, Phanstiel O. J. Med. Chem. 1997; 40: 1475
43f Erickson J, Neidhart DJ, VanDrie J, Kempf DJ, Wang XC, Norbeck DW, Plattner JJ, Rittenhouse JW, Turon M, Wideburg N, Kohlbrenner WE, Simmer R, Helfrich R, Paul DA, Knigge M. Science 1990; 249: 527

For examples of 1,3-amines as ligands or auxiliaries for asymmetric catalysis, see:

43g Busscher GF, Rutjes FP. J. T, van Delft FL. Chem. Rev. 2005; 105: 775
43h Hems WP, Groarke M, Zanotti-Gerosa A, Grasa GA. Acc. Chem. Res. 2007; 40: 1340
43i Kizirian J.-C. Chem. Rev. 2008; 108: 140

44a Zhao C.-H, Liu L, Wang D, Chen Y.-J. Eur. J. Org. Chem. 2006; 2977
44b Giampitro NC, Wolfe JP. J. Am. Chem. Soc. 2008; 130: 12907
44c Lu S.-F, Du D.-M, Xu J, Zhang S.-W. J. Am. Chem. Soc. 2006; 128: 7418
44d Wang J, Li H, Zu L, Jiang W, Wang W. Adv. Synth. Catal. 2006; 348: 2047
44e Anderson JC, Blake AJ, Mills M, Ratcliffe PD. Org. Lett. 2008; 10: 4141
44f Rabalakos C, Wulff WD. J. Am. Chem. Soc. 2008; 130: 13524
44g Yang X, Zhou X, Lin L, Chang L, Liu X, Feng X. Angew. Chem. Int. Ed. 2008; 47: 7079
44h Kurokawa T, Kim M, Du Bois J. Angew. Chem. Int. Ed. 2009; 48: 2777
44i Trost BM, Malhotra S, Olson DE, Maruniak A, Du Bois J. J. Am. Chem. Soc. 2009; 131: 4190
44j Morgen M, Bretzke S, Li P, Menche D. Org. Lett. 2010; 12: 4494
44k Liew SK, He Z, St Denis JD, Yudin AK. J. Org. Chem. 2013; 78: 11637

45 Dagousset G, Drouet F, Masson G, Zhu J. Org. Lett. 2009; 11: 5546

46a Welch WM, Kraska AR, Sarges R, Koe BK. J. Med. Chem. 1984; 27: 1508
46b Lautens M, Rovis T. J. Org. Chem. 1997; 62: 5246
46c Garcia AE, Ouizem S, Cheng X, Romanens P, Kündig EP. Adv. Synth. Catal. 2010; 352: 2306

47 Dagousset G, Erb W, Zhu J, Masson G. Org. Lett. 2014; 16: 2554

For examples of imine/enamine isomerization, see:

48a Katritzky AR, Rachwal B, Rachwal S. J. Org. Chem. 1995; 60: 3993
48b Crousse B, Bégué J.-P, Bonnet-Delpon D. J. Org. Chem. 2000; 65: 5009
48c Talukdar S, Chen C.-T, Fang J.-M. J. Org. Chem. 2000; 65: 3148
48d Yadav JS, Subba Reddy BV, Srinivas R, Madhuri C, Ramalingam T. Synlett 2001; 240
48e Hadden M, Nieuwenhuyzen M, Osborne D, Stevenson PJ, Thompson N, Walker AD. Tetrahedron 2006; 62: 3977
48f Yan R, Liu X, Pan C, Zhou X, Li X, Kang X, Huang G. Org. Lett. 2013; 15: 4876

49a Matsubara R, Kobayashi S. Angew. Chem. Int. Ed. 2006; 45: 7993
49b Chang L, Kuang Y, Qin B, Zhou X, Liu X, Lin L, Feng X. Org. Lett. 2010; 12: 2214

50 Lu M, Lu Y, Zeng X, Li X, Zhong G. Angew. Chem. Int. Ed. 2010; 49: 8588
51 For selected pioneering work on asymmetric α-amination using azodicarboxylates as sources of electrophilic nitrogen, see: Evans DA, Nelson SG. J. Am. Chem. Soc. 1997; 119: 6452
52 Drouet F, Lalli C, Liu H, Masson G, Zhu J. Org. Lett. 2011; 13: 94

53a Hatano M, Moriyama K, Maki T, Ishihara K. Angew. Chem. Int. Ed. 2010; 49: 3823
53b Klussmann M, Ratjen L, Hoffmann S, Wakchaure V, Goddard R, List B. Synlett 2010; 2189

54 Hatano M, Ikeno T, Matsumura T, Torii S, Ishihara K. Adv. Synth. Catal. 2008; 350: 1776

For recent reviews on combining metal and Brønsted acid catalysis, see:

55a Rueping M, Koenigs RM, Atodiresei I. Chem. Eur. J. 2010; 16: 9350
55b Shao ZH, Zhang HB. Chem. Soc. Rev. 2009; 38: 2745
55c Lacour J, Moraleda D. Chem. Commun. 2009; 7073

For selected examples of catalysis by chiral Ca(II) salts, see:

56a Suzuki T, Yamagiwa N, Matsuo Y, Sakamoto S, Yamaguchi K, Shibasaki M, Noyori R. Tetrahedron Lett. 2001; 42: 4669
56b Kumaraswamy G, Jena N, Sastry MN. V, Padmaja M, Markondaiah B. Adv. Synth. Catal. 2005; 347: 867
56c Saito S, Tsubogo T, Kobayashi S. J. Am. Chem. Soc. 2007; 129: 5364
56d Tsubogo T, Saito S, Seki K, Yamashita Y, Kobayashi S. J. Am. Chem. Soc. 2008; 130: 13321
56e Kobayashi S, Tsubogo T, Saito S, Yamashita Y. Org. Lett. 2008; 10: 807
56f Poisson T, Tsubogo T, Yamashita Y, Kobayashi S. J. Org. Chem. 2010; 75: 963
56g Kobayashi S, Yamashita Y. Acc. Chem. Res. 2011; 44: 58
56h Parra A, Reboredo S, Martin Castro AM, Aleman J. Org. Biomol. Chem. 2012; 10: 5001

For a review, see:

57a Harder S. Chem. Rev. 2010; 110: 3852

For an example of a monomeric structure of a Ca complex, see:

57b Mashima K, Sugiyama JH, Kanehisa N, Kai Y, Yasuda H, Nakamura A. J. Am. Chem. Soc. 1994; 116: 6977

58 For an example of a phosphoramide/calcium complex, see: Rueping M, Theissmann T, Kuenkel A, Koenigs RM. Angew. Chem. Int. Ed. 2008; 47: 6798
59 Fluorination of enamides, see: Phipps RJ, Hiramatsu K, Toste FD. J. Am. Chem. Soc. 2012; 134: 8376

For reviews, see:

60a Li G, Kotti SR. S. S, Timmons C. Eur. J. Org. Chem. 2007; 2745
60b Rauniyar V, Lackner AD, Hamilton GL, Toste FD. Science 2011; 334: 1681
60c Denmark SE, Kuester WE, Burk MT. Angew. Chem. Int. Ed. 2012; 51: 10938
60d Chemler SR, Bovino MT. ACS Catal. 2013; 3: 1076
60e Cheng YA, Yu W, Yeung Y.-Y. Org. Biomol. Chem. 2014; 12: 2333

61a Goodman M, Chorev M. Acc. Chem. Res. 1979; 12: 1
61b Chorev M, Goodman M. Acc. Chem. Res. 1993; 26: 266
61c Chorev M, Goodman M. Trends Biotechnol. 1995; 13: 438
61d Fletcher MD, Campbell MM. Chem. Rev. 1998; 98: 763

62 For a review, see: Kataja AO, Masson G. Tetrahedron 2014; in press, DOI: 10.1016/j.tet.2014.06.101
63 Danion-Bougot R, Francis G. Tetrahedron Lett. 1990; 31: 3739

64a Coleman RS, Carpenter AJ. J. Org. Chem. 1992; 57: 5813
64b Coleman RS, Kong J.-S, Richardson TE. J. Am. Chem. Soc. 1999; 121: 9088

65a Matsumura Y, Terauchi J, Yamamoto T. Tetrahedron 1993; 49: 8503
65b Levraud C, Calvet-Vitale S, Bertho G, Dhimane H. Eur. J. Org. Chem. 2008; 1901

66a Kraus GA, Neuenschwander R. Tetrahedron Lett. 1980; 21: 3841
66b Quiroz T, Corona D, Covarruvias A, Avila-Zárraga JG, Romero-Ortega M. Tetrahedron Lett. 2007; 48: 1571

67 Allix A, Lalli C, Retailleau P, Masson G. J. Am. Chem. Soc. 2012; 134: 10389
68 Honjo T, Phipps RJ, Rauniyar V, Toste FD. Angew. Chem. Int. Ed. 2012; 51: 9684

For reviews on organocatalytic asymmetric α-alkylation of aldehydes, see:

69a Alba A.-N, Viciano M, Rios R. ChemCatChem 2009; 1: 437
69b Melchiorre P. Angew. Chem. Int. Ed. 2009; 48: 1360
69c Vesely J, Rios R. ChemCatChem 2012; 4: 942

70 Renaud P, Schubert S. Synlett 1990; 624
71 Curran DP, Eichenberger E, Collis M, Roepel MG, Thoma G. J. Am. Chem. Soc. 1994; 116: 4279
72 Friestad GK, Wu Y. Org. Lett. 2009; 11: 819

For radical additions to enamines, see:

73a Russell GA, Kulkarni SV, Khanna RK. J. Org. Chem. 1990; 55: 1080
73b Russell GA, Wang K. J. Org. Chem. 1991; 56: 3475
73c Narasaka K, Iwakura K, Okauchi T. Chem. Lett. 1991; 20: 423
73d Barton DH. R, Jaszberenyi JC, Theodorakis EA. Tetrahedron 1992; 48: 2613
73e Renaud P, Björup P, Carrupt P.-A, Schenk K, Schubert S. Synlett 1992; 211
73f Schubert S, Renaud P, Carrupt P.-A, Schenk K. Helv. Chim. Acta 1993; 76: 2473
73g Chuang C.-P, Wu Y.-L. Tetrahedron 2004; 60: 1841
73h Tsai A.-I, Chuang C.-P. Tetrahedron 2006; 62: 2235
73i Aurrecoechea JM, Coy CA, Patiño OJ. J. Org. Chem. 2008; 73: 5194

For radical additions to enamides, see:

73j Clark AJ. Chem. Soc. Rev. 2002; 31: 1
73k Curran DP, Guthrie DB, Geib SJ. J. Am. Chem. Soc. 2008; 130: 8437

For recent reviews on photoredox catalysis, see:

74a Zeitler K. Angew. Chem. Int. Ed. 2009; 48: 9785
74b Yoon TP, Ischay MA, Du J. Nat. Chem. 2010; 2: 527
74c Narayanam JM. R, Stephenson CR. J. Chem. Soc. Rev. 2011; 40: 102
74d Teplý F. Collect. Czech. Chem. Commun. 2011; 76: 859
74e Maity S, Zheng N. Synlett 2012; 1851
74f Xuan J, Xiao W.-J. Angew. Chem. Int. Ed. 2012; 51: 6828
74g Tucker JW, Stephenson CR. J. J. Org. Chem. 2012; 77: 1617
74h Shi L, Xia W. Chem. Soc. Rev. 2012; 41: 7687
74i Xi HY. Y, Lei A. Org. Biomol. Chem. 2013; 11: 2387
74j Yoon TP. ACS Catal. 2013; 3: 895
74k Prier CK, Rankic DA, MacMillan DW. C. Chem. Rev. 2013; 113: 5322

75 Courant T, Masson G. Chem. Eur. J. 2012; 18: 423
76 Carboni A, Dagousset G, Magnier E, Masson G. Org. Lett. 2014; 16: 1240

77a Mita T, Kudo Y, Mizukoshi T, Hotta H, Maeda K, Takii S. WO 2004018410, 2004
77b Mita T, Kudo Y, Mizukoshi T, Hotta H, Maeda K, Takii S. JP 2005272452, 2005
77c Rano TA, Kuo G.-H. Org. Lett. 2009; 11: 2812
77d Kawai H, Okusu S, Tokunaga E, Sato H, Shiro M, Shibata N. Angew. Chem. Int. Ed. 2012; 51: 4959
77e Kawai H, Yuan Z, Kitayama T, Tokunaga E, Shibata N. Angew. Chem. Int. Ed. 2013; 52: 5575

For examples of fluorinated amino acids and peptidomimetics, see:

77f Sani M, Bruché L, Chiva G, Fustero S, Piera J, Volonterio A, Zanda M. Angew. Chem. Int. Ed. 2003; 42: 2060
77g Ogu K, Matsumoto S, Akazome M, Ogura K. Org. Lett. 2005; 7: 589
77h Jakowiecki J, Loska R, Makosza M. J. Org. Chem. 2008; 73: 5436
77i Fustero S, Chiva G, Piera J, Sanz-Cervera JF, Volonterio A, Zanda M, Ramirez de Arellano C. J. Org. Chem. 2009; 74: 3122
77j Benhaim C, Bouchard L, Pelletier G, Sellstedt J, Kristofova L, Daigneault S. Org Lett. 2010; 12: 2008

For examples of drugs, see:

77k Fustero S, Albert L, Aceña JL, Sanz-Cervera JF, Asensio A. Org. Lett. 2008; 10: 605
77l Feng C, Loh T.-P. Chem. Sci. 2012; 3: 3458

78a Nagib DA, Scott ME, MacMillan DW. C. J. Am. Chem. Soc. 2009; 131: 10875
78b Pham PV, Nagib DA, MacMillan DW. C. Angew. Chem. Int. Ed. 2011; 50: 6119
78c Nguyen JD, Tucker JW, Konieczynska MD, Stephenson CR. J. J. Am. Chem. Soc. 2011; 133: 4160
78d Studer A. Angew. Chem. Int. Ed. 2012; 51: 8950
78e Wallentin C, Nguyen JD, Finkbeiner P, Stephenson CR. J. J. Am. Chem. Soc. 2012; 134: 8875
78f Iqbal N, Choi S, Kim E, Cho EJ. J. Org. Chem. 2012; 77: 11383
78g Yasu Y, Koike T, Akita M. Angew. Chem. Int. Ed. 2012; 51: 9567
78h Yasu Y, Koike T, Akita M. Org. Lett. 2013; 15: 2136
78i Yasu Y, Koike T, Akita M. Chem. Commun. 2013; 49: 2037
78j Mizuta S, Verhoog S, Engle KM, Khotavivattana T, O’Duill M, Wheelhouse K, Rassias G, Médebielle M, Gouverneur V. J. Am. Chem. Soc. 2013; 135: 2505
78k Kim E, Choi S, Kim H, Cho EJ. Chem. Eur. J. 2013; 19: 6209
78l Mizuta S, Engle KM, Verhoog S, Galicia-López O, O’Duill M, Médebielle M, Wheelhouse K, Rassias G, Thompson AL, Gouverneur V. Org. Lett. 2013; 15: 1250
78m Jiang H, Cheng Y, Zhang Y, Yu S. Eur. J. Org. Chem. 2013; 5485
78n Wilger DJ, Gesmundo NJ, Nicewicz DA. Chem. Sci. 2013; 4: 3160
78o Xu P, Xie J, Xue Q, Pan C, Cheng Y, Zhu C. Chem. Eur. J. 2013; 19: 14039
78p Iqbal N, Jung J, Park S, Cho EJ. Angew. Chem. Int. Ed. 2014; 53: 539
78q Mizuta S, Verhoog S, Wang X, Shibata N, Gouverneur V, Médebielle M. J. Fluorine Chem. 2013; 155: 124

79 For an example of Cu-catalyzed oxytrifluoromethylation of α-substituted enamides, see: Feng C, Loh T.-P. Chem. Sci. 2012; 3: 3458
80 Matoušek V, Pietrasiak E, Schwenk R, Togni A. J. Org. Chem. 2013; 78: 6763
81 Furst L, Matsuura BS, Narayanam JM. R, Tucker JW, Stephenson CR. J. Org. Lett. 2010; 12: 3104
82 Wang A, Fang Y, Long L, Song Y, Yu W, Zhao W, Cifuentes MP, Humphrey MG, Zhang C. Chem. Eur. J. 2013; 19: 13989

83a Beeson TD, Mastracchio A, Hong J.-B, Ashton K, MacMillan DW. C. Science 2007; 316: 582
83b Mastracchio A, Warkentin AA, Walji AM, MacMillan DW. C. Proc. Natl. Acad. Sci. U. S. A. 2010; 107: 20648 ; and references cited therein

For highlights, see:

83c Wessig P. Angew. Chem. Int. Ed. 2006; 45: 2168
83d Mukherjee S, List B. Nature 2007; 447: 152
83e Bertelsen S, Nielsen M, Jørgensen KA. Angew. Chem. Int. Ed. 2007; 46: 7356

84a Sibi MP, Hasegawa M. J. Am. Chem. Soc. 2007; 129: 4124
84b Van Humbeck JF, Simonovich SP, Knowles RR, MacMillan DW. C. J. Am. Chem. Soc. 2010; 132: 10012
84c Akagawa K, Fujiwara T, Sakamoto S, Kudo K. Org. Lett. 2010; 12: 1804
84d Simonovich SP, Van Humbeck JF, MacMillan DW. C. Chem. Sci. 2012; 3: 58

For selected reviews of the use of CAN as a single-electron oxidant, see:

85a Nair V, Deepthi A. Chem. Rev. 2007; 107: 1862
85b Nair V, Balagopal L, Rajan R, Mathew J. Acc. Chem. Res. 2004; 37: 21

86a Clift MD, Taylor CN, Thomson RJ. Org. Lett. 2007; 9: 4667
86b Avetta CT. Jr, Konkol LC, Taylor CN, Dugan KC, Stern CL, Thomson RJ. Org. Lett. 2008; 10: 5621
86c Konkol LC, Jones BT, Thomson RJ. Org. Lett. 2009; 11: 5550

For intramolecular α-alkylation of aldehydes, see:

87a Comito RJ, Finelli FG, MacMillan DW. C. J. Am. Chem. Soc. 2013; 135: 9358

For Intramolecular α-allylation of aldehydes, see:

87b Pham PV, Ashton K, MacMillan DW. C. Chem. Sci. 2011; 2: 1470

For α-enolation of aldehydes, see:

87c Jang H.-Y, Hong J.-B, MacMillan DW. C. J. Am. Chem. Soc. 2007; 129: 7004

88 Bekkaye M, Masson G. Org. Lett. 2014; 16: 1510
89 Devery JJ. III, Conrad JC, MacMillan DW. C, Flowers RA. II. Angew. Chem. Int. Ed. 2010; 49: 6106
90 Sunazuka T, Yoshida K, Kojima N, Shirahata T, Hirose T, Handa M, Yamamoto D, Harigaya Y, Kuwajima I, Ōmura S. Tetrahedron Lett. 2005; 46: 1459
91 Chanon M, Rajzmann M, Chanon F. Tetrahedron 1990; 46: 6193
92 Drouet F, Zhu J, Masson G. Adv. Synth. Catal. 2013; 355: 3563
93 Bekkaye M, Su Y, Masson G. Eur. J. Org. Chem. 2013; 3978