Cobalt–Catalyzed Oxidative α-Cyanation of Tertiary Aromatic Amines with Trimethylsilyl Cyanide and tert-Butyl Hydroperoxide

Norio Sakai; Akihiro Mutsuro; Reiko Ikeda; Takeo Konakahara

doi:10.1055/s-0033-1338937

Synlett, Table of Contents

Synlett 2013; 24(10): 1283-1285
DOI: 10.1055/s-0033-1338937

letter

Cobalt–Catalyzed Oxidative α-Cyanation of Tertiary Aromatic Amines with Trimethylsilyl Cyanide and tert-Butyl Hydroperoxide

Authors

Norio Sakai*

Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science (RIKADAI), Noda, Chiba 278-8510, Japan Fax: +81(4)71239890 Email: sakachem@rs.noda.tus.ac.jp
Akihiro Mutsuro

Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science (RIKADAI), Noda, Chiba 278-8510, Japan Fax: +81(4)71239890 Email: sakachem@rs.noda.tus.ac.jp
Reiko Ikeda

Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science (RIKADAI), Noda, Chiba 278-8510, Japan Fax: +81(4)71239890 Email: sakachem@rs.noda.tus.ac.jp
Takeo Konakahara

Department of Pure and Applied Chemistry, Faculty of Science and Technology, Tokyo University of Science (RIKADAI), Noda, Chiba 278-8510, Japan Fax: +81(4)71239890 Email: sakachem@rs.noda.tus.ac.jp

Abstract

All articles of this category

Abstract

In this Letter is described that a cobalt(II)–tert-butyl hydroperoxide oxidizing system was used to catalyze the α-cyanation of aromatic tertiary amines in the presence of trimethylsilyl cyanide to produce the corresponding α-aminonitriles in good yields.

Key words

cobalt - oxidation - cyanation - aminonitriles - tertiary amines

Full Text

References

References and Notes

1a North M. Angew. Chem. Int. Ed. 2004; 43: 4126
1b Enders D, Shilvock JP. Chem. Soc. Rev. 2000; 29: 359

2a Chiba T, Saitoh I, Okimoto M, Tanase T, Yano S. J. Org. Chem. 1999; 64: 2516
2b Kantlehner W, Haug E, Frick W, Speh P, Bräuner H.-J. Synthesis 1984; 358
2c Bredereck H, Simchen G, Kantlehner W. Chem. Ber. 1971; 104: 924
2d Deyrup JA, Greenwald RB. J. Am. Chem. Soc. 1965; 87: 4538

Selected reviews for asymmetric Strecker-type reaction, see:

3a Wang J, Liu X, Feng X. Chem. Rev. 2011; 111: 6947
3b Das B, Damodar K, Shashikanth B, Srinivas Y, Kalavathi I. Synlett 2008; 3133
3c Gröger H. Chem. Rev. 2003; 103: 2795

4a Murahashi S.-I, Zhang D. Chem. Soc. Rev. 2008; 37: 1490
4b Murahashi S.-I, Nakae T, Terai H, Komiya N. J. Am. Chem. Soc. 2008; 130: 11005
4c Murahashi S.-I, Komiya N, Terai H. Angew. Chem. Int. Ed. 2005; 44: 6931
4d Murahashi S.-I, Komiya N, Terai H, Nakae T. J. Am. Chem. Soc. 2003; 125: 15312
4e Murahashi S.-I, Naota T, Miyaguchi N, Nakato T. Tetrahedron Lett. 1992; 33: 6991
4f Murahashi S, Naota T, Kuwabara T, Saito T, Kumobayashi H, Akutagawa S. J. Am. Chem. Soc. 1990; 112: 7820

5a Singhal S, Jain SL, Sain B. Adv. Synth. Catal. 2010; 352: 1338
5b Singhal S, Jain SL, Sain B. Chem. Commun. 2009; 2371

6a Zhang Y, Peng H, Zhang M, Cheng Y, Zhu C. Chem. Commun. 2011; 47: 2354
6b Han W, Ofial AR. Chem. Commun. 2009; 5024

7 Alagiri K, Prabhu KR. Org. Biomol. Chem. 2012; 10: 835
8 Rueping M, Zhu S, Koenigs RM. Chem. Commun. 2011; 47: 12709 ; and references cited therein

For selected metal-free oxidative α-cyanation, see:

9a Allen JM, Lambert TH. J. Am. Chem. Soc. 2011; 133: 1260
9b Liu L, Wang Z, Fu X, Yan C.-H. Org. Lett. 2012; 14: 5692

10 Murahashi S.-i, Komiya N. EP 1174419A1, 2002 ; Chem. Abstr. 2002, 136, 118063.
11 During this study, Doyle and co-workers reported that a Co(OAc)₂-TBHP oxidizing system undertook an oxidative Mannich-type reaction through a single electron transfer, see: Ratnikov MO, Doyle MP. J. Am. Chem. Soc. 2013; 135: 1549
12 General Procedure To a 5 mL screw vial containing freshly distilled MeOH (0.6 mL) were successively added 1.0 M CoCl₂ in a MeOH solution (6.0 μL, 0.0060 mmol), aromatic tertiary amine (0.60 mmol), TMSCN (188 μL, 2.50 mmol), and 5.5 M TBHP in decane solution (164 μL, 0.900 mmol) under an ambient atmosphere. The resultant mixture was stirred at 60 °C (bath temperature), and consumption of the starting amine was monitored by GC analysis. After the reaction the resultant mixture was quenched with a aqueous solution of Na₂CO₃. The aqueous layer was extracted with CH₂Cl₂, then the organic phases were dried over anhyd Na₂SO₄, filtered, and evaporated under a reduced pressure. The crude product was purified by silica chromatography (hexane–EtOAc, 4:1) to give the corresponding α-aminonitrile. Selected Data for the Prepared Aminonitriles N-Methyl-N-(4-methylphenyl)aminoacetonitrile (1) ¹H NMR (500 MHz, CDCl₃): δ = 2.28 (s, 3 H), 2.95 (s, 3 H), 4.12 (s, 2 H), 6.78 (d, 2 H, J = 9.0 Hz), 7.11 (d, 2 H, J = 9.0 Hz). ¹³C NMR (125 MHz, CDCl₃): δ = 20.3, 39.4, 42.8, 115.3, 115.4, 129.8, 129.9, 145.6. MS (EI): m/z (%) = 160 (100) [M⁺]. N-Methyl-N-(4-bromophenyl)aminoacetonitrile (7) ¹H NMR (500 MHz, CDCl₃): δ = 2.99 (s, 3 H), 4.15 (s, 2 H), 6.72 (d, 2 H, J = 9.0 Hz), 7.38 (d, 2 H, J = 9.0 Hz). ¹³C NMR (125 MHz, CDCl₃): δ = 39.3, 42.1, 112.5, 115.1, 116.4, 132.2, 146.7. MS (EI): m/z (%) = 224 (100) [M⁺]. The characterization of other α-aminonitriles was confirmed by ¹H NMR and ¹³C NMR spectroscopic analysis.

13a Li Z, Bohle DS, Li C.-J. Proc. Natl. Acad. Sci. U.S.A. 2006; 103: 8928
13b Boess E, Schmitz C, Klussmann M. J. Am. Chem. Soc. 2012; 134: 5317

14 One reviewer pointed out that a reaction of CoCl₂ with TBHP initially generated Co(III)Cl₂(OH) and a tert-butyloxy radical (t-BuO^•, Equation 1, a). Those species are acceptable. However, both species would be promptly oxidized by an excess amount of TBHP to finally produce a tert-butylperoxy radical (t-BuOO^•) through the following plausible oxidation steps (Equation 1, b and c). Also, several groups reported that ruthenium-, rhodium-, or copper-catalyzed oxidative substitution of amines with TBHP, producing not the N,O-aminal derivative, but the amino peroxide derivative.^4f,13b,15 Moreover, Doyle et al. showed that Co(OAc)₂ converted TBHP into the tert-butylperoxy radical.¹¹ Therefore, we proposed the initial formation of the tert-butylperoxy radical by CoCl₂ as the plausible reaction path.
15 Catino AJ, Nichols JM, Nettles BJ, Doyle MP. J. Am. Chem. Soc. 2006; 128: 5648