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Nickel-Catalyzed Denitrogenative Annulation Reactions of 1,2,3-Benzotriazin-4(3H)-ones with 1,3-Dienes and Alkenes Tomoya Miura, Masao Morimoto, Motoshi Yamauchi, and Masahiro Murakami* Department of Synthetic Chemistry and Biological Chemistry, Kyoto University, Katsura, Kyoto 615-8510, Japan
[email protected] Received May 5, 2010
1,2,3-Benzotriazin-4(3H)-ones react with 1,3-dienes in the presence of a nickel(0)/phosphine complex to give a variety of 3,4-dihydroisoquinolin-1(2H)-ones. Oxidative insertion of nickel(0) into the triazinone moiety prompts extrusion of dinitrogen to give a five-membered ring azanickelacyclic intermediate. Subsequent insertion of 1,3-dienes into the nickel-carbon bond followed by allylic amidation affords 3,4-dihydroisoquinolin-1(2H)-ones. Alkenes also undergo insertion into the five-membered ring azanickelacyclic intermediate, and subsequent reductive elimination gives 3-substituted 3,4-dihydroisoquinolin-1(2H)-ones.
Transition-metal-catalyzed annulation reactions provide an efficient synthetic route to heterocyclic compounds.1 Heterometalacyclic complexes are often involved as the key intermediates, which can induce the incorporation of unsaturated molecules into the heterocyclic skeleton. It has been demonstrated that relatively stable heterocyclic compounds act as precursors of heterometalacyclic complexes. Oxidative addition to a low-valent transition metal and extrusion of gaseous molecules such as N2, CO, and CO2 lead to the formation of new heterocyclic systems. For example, pyridotriazoles2 reacted with alkynes in the pre(1) For reviews, see: (a) Nakamura, I.; Yamamoto, Y. Chem. Rev. 2004, 104, 2127. (b) Zeni, G.; Larock, R. C. Chem. Rev. 2004, 104, 2285. (c) D’Souza, D. M.; M€ uller, T. J. J. Chem. Soc. Rev. 2007, 36, 1095. (2) (a) Chuprakov, S.; Hwang, F. W.; Gevorgyan, V. Angew. Chem., Int. Ed. 2007, 46, 4757. (b) Chuprakov, S.; Gevorgyan, V. Org. Lett. 2007, 9, 4463. (3) For related examples, see: (a) Horneff, T.; Chuprakov, S.; Chernyak, N.; Gevorgyan, V.; Fokin, V. V. J. Am. Chem. Soc. 2008, 130, 14972. (b) Miura, T.; Yamauchi, M.; Murakami, M. Chem. Commun. 2009, 1470. (c) Nakamura, I.; Nemoto, T.; Shiraiwa, N.; Terada, M. Org. Lett. 2009, 11, 1055. (d) Chuprakov, S.; Kwok, S. W.; Zhang, L.; Lercher, L.; Fokin, V. V. J. Am. Chem. Soc. 2009, 131, 18034. (e) Grimster, N.; Zhang, L.; Fokin, V. V. J. Am. Chem. Soc. 2010, 132, 2510.
DOI: 10.1021/jo1008756 r 2010 American Chemical Society
Published on Web 07/06/2010
sence of a rhodium catalyst to give indolizine derivatives with extrusion of N2.3 Phthalimide,4a phthalic anhydride,4b and isatoic anhydride4c were also utilized in the nickel-catalyzed annulation reaction with alkynes to form isoquinolin1(2H)-ones, isochromen-1-ones, and quinolin-4(1H)-ones, respectively, with extrusion of CO or CO2.5 We have recently shown that nickel-catalyzed denitrogenative annulation reactions of 1,2,3-benzotriazin-4(3H)-ones with alkynes6a and allenes6b provide new synthetic approaches to isoquinolin-1(2H)-ones and 4-methylene-3,4-dihydroisoquinolin-1(2H)-ones. Thus, 1,2,3-benzotriazin-4(3H)-ones can be exploited as a precursory platform for the synthesis of isoquinolin-1(2H)-one derivatives,7 which are found in a wide variety of plant alkaloids and bioactive compounds. We next examined the possibility of their reactions with other unsaturated molecules to expand the reaction scope. In this paper are described the results of the nickel-catalyzed annulation reactions of 1,2,3-benzotriazin-4(3H)-ones with 1,3dienes and alkenes. The model substrate, N-tolyl-1,2,3-benzotriazin-4(3H)one (1a), was readily prepared from methyl anthranilate in two steps (eq 1);8 methyl anthranilate was diazotized by NaNO2 and then coupled with 4-toluidine to give methyl 2-[3-(4-tolyl)triaz-2-enyl]benzoate. Subsequent heating in refluxing ethanol prompted six-membered ring closure to afford 1a as a white solid (78% yield over two steps).
In addition, we developed an alternative simple route to 1a from commercially available NH-1,2,3-benzotriazin-4(3H)one through direct N-arylation catalyzed by copper (eq 2).9 When NH-1,2,3-benzotriazin-4(3H)-one was treated with 4-iodotoluene (1.5 equiv) in the presence of CuI (10 mol %) and 2-isobutyrylcyclohexanone (20 mol %) in DMSO at 80 °C, an N-arylation reaction took place and 1a was obtained in 95% yield. The isolated 1a was stable at room temperature and could be kept for months without any decomposition.10
We initiated our study by conducting a reaction of 1a with 2,3-dimethylbuta-1,3-diene (2a, 2 equiv) in THF at 60 °C in (4) (a) Kajita, Y.; Matsubara, S.; Kurahashi, T. J. Am. Chem. Soc. 2008, 130, 6058. (b) Kajita, Y.; Kurahashi, T.; Matsubara, S. J. Am. Chem. Soc. 2008, 130, 17226. (c) Yoshino, Y.; Kurahashi, T.; Matsubara, S. J. Am. Chem. Soc. 2009, 131, 7494. (5) For related examples, see: (a) O’Brien, E. M.; Bercot, E. A.; Rovis, T. J. Am. Chem. Soc. 2003, 125, 10498. (b) Wang, C.; Tunge, J. A. J. Am. Chem. Soc. 2008, 130, 8118.
J. Org. Chem. 2010, 75, 5359–5362
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JOC Note SCHEME 1. Ni(0)-Catalyzed Reaction of 1a with 2a Using PMe3 as the Ligand
Miura et al. TABLE 1. Ni(0)-Catalyzed Reaction of 1a with 2a: Screening of Phosphine Ligandsa entry ligand (mol %) yield of 3aa (%) yield of 4aa (%) PMe2Ph (20) PMePh2 (20) PPh3 (20) P(n-Bu)3 (20) P(t-Bu)3 (20) Dppb (10) Dppf (10)
1 2 3 4 5 6 7
21
