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Aldehyde- and Ketone-Induced Tandem Decarboxylation-Coupling (Csp3-Csp) of Natural r-Amino Acids and Alkynes Hai-Peng Bi,†,‡ Qingfeng Teng,‡ Min Guan,‡ Wen-Wen Chen,† Yong-Min Liang,*,‡ Xiaojun Yao,*,‡ and Chao-Jun Li*,† † Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montreal, Quebec H3A 2K6, Canada and ‡State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, People’s Republic of China
[email protected];
[email protected];
[email protected] Received October 29, 2009
An interesting aldehyde- and ketone-induced intermolecular tandem decarboxylation-coupling (Csp3-Csp) catalyzed by copper with use of natural R-amino acids as starting materials is developed under neutral conditions with the production of CO2 and H2O as the only byproducts. Various functionalized nitrogen-containing compounds were obtained by this method. In these processes, interesting regioselectivites of the alkylation were observed, which has been rationalized by the relative stability of proposed resonance structures based on computation methods.
Introduction The transition metal-catalyzed cross-coupling reactions (e.g., Negishi,1 Stille,2 Suzuki-Miyaura,3 Sonogashira,4 and Kumada5 couplings) have been established as convenient, practical, and effective methods for constructing C-C bonds in modern organic synthesis.6 Although they have been employed in a broad range of applications,7 there are still disadvantages such as the requirement of usually expensive (1) (a) Negishi, E.; Valente, L. F.; Kobayashi, M. J. Am. Chem. Soc. 1980, 102, 3298–3299. (b) Negishi, E. Acc. Chem. Res. 1982, 15, 340–348. (c) Zeng, X.; Quian, M.; Hu, Q.; Negishi, E. Angew. Chem., Int. Ed. 2004, 43, 2259– 2263. (2) Farina, V.; Krishnamurthy, V.; Scott, W. J. Org. React. 1997, 50, 1–652. (3) (a) Miyaura, N.; Suzuki, A. Chem. Rev. 1995, 95, 2457–2483. (b) Littke, A. F.; Fu, G. C. Angew. Chem., Int. Ed. 1998, 37, 3387–3388. (c) Wolfe, J. P.; Buchwald, S. P. Angew. Chem., Int. Ed. 1999, 38, 2413–2416. (d) Zapf, A.; Ehrentraut, A.; Beller, M. Angew. Chem., Int. Ed. 2000, 39, 4153–4155. (e) Molander, G. A.; Biolatto, B. J. Org. Chem. 2003, 68, 4302–4314. (4) (a) Sonogashira, K. J. Organomet. Chem. 2002, 653, 46–49. (b) Negishi, E.; Anastasia, L. Chem. Rev. 2003, 103, 1979–2017. (5) (a) Tamao, K.; Sumitani, K.; Kumada, M. J. Am. Chem. Soc. 1972, 94, 4374–4376. (b) Corriu, R. J. P.; Masse, J. P. J. Chem. Soc., Chem. Commun. 1972, 144a. (c) Kumada, M. Pure Appl. Chem. 1980, 52, 669–679. (6) (a) Diederich, F.; Stang, P. J., Eds. Metal-Catalyzed Cross-Coupling Reactions; Wiley-VCH: New York, 1998. (b) de Meijere, A.; Diederich, F., Eds. Metal Catalyzed Cross-Coupling Reactions, 2nd ed.; Wiley-VCH: Chichester, UK, 2004; Vols. 1 and 2. (7) Nicolaou, K. C.; Bulger, P. G.; Sarlah, D. Angew. Chem., Int. Ed. 2005, 44, 4442–4489.
DOI: 10.1021/jo902319h r 2010 American Chemical Society
Published on Web 01/07/2010
transition metal catalysts and producing stoichiometric quantities of unwanted metal/metalloid byproducts in the transmetalation steps. Recently, interest in the area of decarboxylative coupling has increased rapidly due to the fact that these reactions occur under relatively neutral conditions, avoiding the use of preformed “organometallic reagents” that are typically necessary for transmetalation and eliminating the stoichiometric quantities of unwanted metal/ metalloid byproducts.8,9 (8) (a) Myers, A. G.; Tanaka, D.; Mannion, M. R. J. Am. Chem. Soc. 2002, 124, 11250–11251. (b) Tanaka, D.; Romeril, S. P.; Myers, A. G. J. Am. Chem. Soc. 2005, 127, 10323–10333. (c) Rayabarapu, D. K.; Tunge, J. A. J. Am. Chem. Soc. 2005, 127, 13510–13511. (d) Gooβen, L. J.; Deng, G.; Levy, L. M. Science 2006, 313, 662–664. (e) Burger, E. C.; Tunge, J. A. J. Am. Chem. Soc. 2006, 128, 10002–10003. (f) Forgione, P.; Brochu, M.-C.; St-Onge, M.; Thesen, K. H.; Bailey, M. D.; Bilodeau, F. J. Am. Chem. Soc. 2006, 128, 11350–11351. (g) Waetzig, S. R.; Tunge, J. A. J. Am. Chem. Soc. 2007, 129, 4138–4139. (h) Gooβen, L. J.; Rodriguez, N.; Melzer, B.; Linder, C.; Deng, G.; Levy, L. M. J. Am. Chem. Soc. 2007, 129, 4824–4833. (i) Waetzig, S. R.; Tunge, J. A. J. Am. Chem. Soc. 2007, 129, 14860–14861. (j) Gooβen, L. J.; Rodrı´ guez, N.; Linder, C. J. Am. Chem. Soc. 2008, 130, 15248–15249. (k) Knight, J. G.; Ainge, S. W.; Harm, A. M.; Harwood, S. J.; Maughan, H. I.; Armour, D. R.; Hollinshead, D. M.; Jaxa-Chamiec, A. A. J. Am. Chem. Soc. 2000, 122, 2944–2945. (l) Trost, B. M.; Xu, J. J. Am. Chem. Soc. 2005, 127, 17180–17181. (m) Bourgeois, D.; Craig, D.; King, N. P.; Mountford, D. M. Angew. Chem., Int. Ed. 2005, 44, 618–621. (n) Mohr, J. T.; Nishimata, T.; Behenna, D. C.; Stoltz, B. M. J. Am. Chem. Soc. 2006, 128, 11348–11349. (9) For a review, see: Gooβen, L. J.; Rodriguez, N.; Gooβen, K. Angew. Chem., Int. Ed. 2008, 47, 3100–3120.
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JOC Article SCHEME 1. Copper-Catalyzed Oxidative Decarboxylative Coupling of Tertiary R-Amino Acids (Path A) and AldehydeInduced Decarboxylation-Coupling of Secondary R-Amino Acids (Path B)
To date, while seeking selective methods to functionalize the R Csp3-H bond of nitrogen-containing compounds,10 we have developed various Cross-DehydrogenativeCoupling (CDC) by directly utilizing two different C-H bonds.11 While these reactions provided the simplest and most direct approach to generate such compounds, the scope of the reactions and the regioselectivity of the C-C bond to be formed are still relatively limited. Alternatively, the carboxylic group of R-amino acids provides the possibility for site-specific functionalization of R-amino acids skeletons, using decarboxylative coupling reactions to generate amine derivatives. In the meantime, R-amino acids are often more readily accessible than other compounds in nature and are among the most attractive synthons for cross-coupling.12 With this notion in mind, very recently, we have developed a C-C bond-forming reaction based on a copper- and ironcatalyzed oxidative decarboxylative coupling of sp3-hybridized carbons of R-amino acids (Scheme 1, path A).13 Although these results provide new and alternative ways to construct different Csp3-Csp, Csp3-Csp2, and Csp3-Csp3 bonds, there are still several limitations for these methods. First, a stoichiometric quantity of peroxide was used. Avoiding the use of peroxide would offer a more atom-economical and much safer process.14 Second, the tertiary R-amino acids described by Path A (protected by benzyl groups) require preparation in separate steps in advance, which also generates waste. Finally, the oxidative coupling methods are not applicable to secondary R-amino acids, which are more prevalent in nature. Thus, the direct R-functionalization of existing secondary R-amino acids is highly desirable and synthetically useful. To address these challenges, herein (10) Godula, K.; Sames, D. Science 2006, 312, 67–72. (11) (a) Li, Z.; Li, C.-J. J. Am. Chem. Soc. 2004, 126, 11810–11811. (b) Li, Z.; Bohle, D. S.; Li, C.-J. Proc. Natl. Acad. Sci. U.S.A. 2006, 103, 8928–8933. (c) Zhao, L.; Li, C.-J. Angew. Chem., Int. Ed. 2008, 47, 7075–7078. (d) Zhao, L.; Basle, O.; Li, C.-J. Proc. Natl. Acad. Sci. U.S.A. 2009, 106, 4106–4111. For an account, see: (e) Li, C.-J. Acc. Chem. Res. 2009, 42, 335–344. (12) (a) Tyrrell, E.; Brookes, P. Synthesis 2004, 469–483. (b) Handy, S. T.; Sabatini, J. J. Org. Lett. 2006, 8, 1537–1539. (c) Flegeau, E. F.; Popkin, M. E.; Greaney, M. F. Org. Lett. 2006, 8, 2495–2498. (d) Moon, J.; Jeong, M.; Nam, H.; Ju, J.; Moon, J. H.; Jung, H. M.; Lee, S. Org. Lett. 2008, 10, 945–948. (13) (a) Bi, H.-P.; Zhao, L.; Liang, Y.-M.; Li, C.-J. Angew. Chem., Int. Ed. 2009, 48, 792–795. (b) Bi, H.-P.; Chen, W.-W.; Liang, Y.-M.; Li, C.-J. Org. Lett. 2009, 11, 3246–3249. (14) (a) Trost, B. M. Science 1991, 254, 1471–1477. (b) Trost, B. M. Acc. Chem. Res. 2002, 35, 695–705. (15) We also developed other methods for the synthesis of propargylamines, see: (a) Li, C.-J.; Wei, C. Chem. Commun. 2002, 268–269. (b) Wei, C.; Li, C.-J. J. Am. Chem. Soc. 2003, 125, 9584–9585. For accounts, see: (c) Wei, C.; Li, Z.; Li, C.-J. Synlett 2004, 1472–1483. (d) Li, C.-J. Acc. Chem. Res. accepted for publication.
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Bi et al. TABLE 1.
Optimization of Reaction Conditionsa
entry
catalyst
temp (°C)
NMR yieldb (%)
1 2 3 4 5 6 7 8 9 10
Au(PPh3)Cl AuCl3 Ag(PPh3)F CuOTf Cu(OTf)2 CuBr2 CuBr CuI CuI CuI
100 100 100 100 100 100 100 100 130 130
