Abstract
Background: The versatile 2-alkynylbenzamde has been reported to produce many privileged skeletons, like isoquinolin-1-ones, isocoumarin-1-imines, isoindolin-1-ones, and isobenzofuran- 1-imines. Recently, we reported the projected transformation using copper salt (CuCl2) as a catalyst under the O2 atmosphere. To expand the scope of the reaction, we used another inexpensive metal salt, MnO2, as a catalyst.
Methods: The paper aims to explore a manganese-catalyzed reaction of 2-alkynylbenzamide under an O2 balloon for the synthesis of 3-hydroxylisoquinolin-1,4-dione.
Results: Results on reaction scope shows the 10 mol% MnO2 in O2 atmosphere and DCE solvent catalyzed the cyclization of 2-alkynylbenzamide to produce 3-hydroxylisoquinolin-1,4-diones in 40-68% isolated yields. The reaction proceeds through a regioselective N-center radical 6-endo-dig aza-cyclization pathway.
Conclusion: We have developed a manganese-catalyzed cyclization of 2-alkynlbenzamide for the synthesis of 3-hydroxylisoquinolin-1,4-diones under an O2 balloon. It is believed that the N-center radical-based 6-endo dig aza-cyclization proceeded in a regioselective manner.
Keywords: 2-Alkynylbenzamide, manganese catalysis, hydroxyliosoquinolin-1, 4-dione, 6-endo-dig cyclization, catalyst, MnO2.
Graphical Abstract
[http://dx.doi.org/10.1039/C9CS00478E]
(b) Sun, K.; Shan, H.; Lu, G.; Cai, C.; Beller, M. Synthesis of N-heterocycles via oxidation-free dehydrocyclization of alcohol using heter-ogenerous catalysts. Angew. Chem. Int. Ed., 2021.
[http://dx.doi.org/10.1002/anie.2021104979]
[http://dx.doi.org/10.1002/cssc.202101586] [PMID: 34402206]
(b) Gao, Y.; Zhao, Q.; Li, L.; Ma, Y. Synthesis of six-membered N-heterocycles frameworks based on intramolecular metal-free N-centered radical chemistry. Chem. Rec., 2022, 22(2), e202100218.
[http://dx.doi.org/10.1002/tcr.202100218]
[http://dx.doi.org/10.1021/acs.accounts.9b00472] [PMID: 31774646]
(b) Kumar, G.; Pradhan, S.; Chatterjee, I. N-centered radical directed remote C-H bond functionalization via hydrogen atom transfer. Chem. Asian J., 2020, 15(6), 651-672.
[http://dx.doi.org/10.1002/asia.201901744] [PMID: 32011095]
[http://dx.doi.org/10.1039/C7CS00017K] [PMID: 29125611]
(b) Margrey, K.A.; Nicewicz, D.A. A general approach to catalytic alkene anti-markovnikov hydrofunctionalization reactions via acridini-um photoredox catalysis. Acc. Chem. Res., 2016, 49(9), 1997-2006.
[http://dx.doi.org/10.1021/acs.accounts.6b00304] [PMID: 27588818]
[http://dx.doi.org/10.1021/acs.chemrev.5b00514] [PMID: 27111159]
(b) Pirnot, M.T.; Wang, Y.M.; Buchwald, S.L. Copper hydride catalyzed hydroamination of alkenes and alkynes. Angew. Chem. Int. Ed. Engl., 2016, 55(1), 48-57.
[http://dx.doi.org/10.1002/anie.201507594] [PMID: 26661678]
(c) Yoshida, H. Borylation of alkynes under base/coinage metal catalysis: Some recent developments. ACS Catal., 2016, 6, 1799-1811.
[http://dx.doi.org/10.1021/acscatal.5b02973]
[http://dx.doi.org/10.1039/C4OB01618A] [PMID: 25297655]
[http://dx.doi.org/10.1002/tcr.201500219] [PMID: 26493018]
(b) Qiu, G.; Kuang, Y.; Wu, J. N-Imide Ylide-Based Reactions: C-H functionalization, nucleophilic addition and cycloaddition. Adv. Synth. Catal., 2014, 356, 3483-3504.
[http://dx.doi.org/10.1002/adsc.201400631]
(c) Wu, X.F. Toward greener oxidative transformations: Base-metal catalysts and metal-free reactions. Chem. Rec., 2015, 15(5), 949-963.
[http://dx.doi.org/10.1002/tcr.201500207] [PMID: 26403603]
[http://dx.doi.org/10.1039/C7CC01861D] [PMID: 28443851]
(b) Chary, R.G.; Dhananjaya, G.; Prasad, K.V.; Vaishaly, S.; Ganesh, Y.S.; Dulla, B.; Kumar, K.S.; Pal, M. A simple access to N-(un)substituted isoquinolin-1(2H)-ones: Unusual formation of regioisomeric isoquinolin-1(4H)-ones. Chem. Commun. (Camb.), 2014, 50(51), 6797-6800.
[http://dx.doi.org/10.1039/c4cc01580k] [PMID: 24837646]
(c) Yang, Y.; Liu, Y.; Zhu, R.; Liu, C.; Zhang, D. Theoretical insight into the mechanism and origin of divergent reactivity in the synthesis of benzo-heterocycles from o-alkynylbenzamides catalyzed by gold and platinum complexes. J. Org. Chem., 2019, 84(15), 9705-9713.
[http://dx.doi.org/10.1021/acs.joc.9b01441] [PMID: 31246456]
[http://dx.doi.org/10.1002/ejoc.201500797]
(b) Álvarez, R.; Martínez, C.; Madich, Y.; Denis, J.G.; Aurrecoechea, J.M.; de Lera, Á.R. A general synthesis of alkenyl-substituted benzo-furans, indoles, and isoquinolones by cascade palladium-catalyzed heterocyclization/oxidative Heck coupling. Chemistry, 2010, 16(42), 12746-12753.
[http://dx.doi.org/10.1002/chem.201001535] [PMID: 20859966]
[http://dx.doi.org/10.1021/acs.joc.7b02903] [PMID: 29457724]
(b) Bantreil, X.; Bourderioux, A.; Mateo, P.; Hagerman, C.E.; Selkti, M.; Brachet, E.; Belmont, P. Phosphine-triggered selectivity switch in silver-catalyzed o-alkynylbenzohydroxamic acid cycloisomerizations. Org. Lett., 2016, 18(19), 4814-4817.
[http://dx.doi.org/10.1021/acs.orglett.6b02235] [PMID: 27618124]
[http://dx.doi.org/10.1002/ejoc.201403534]
(b) Mehta, S.; Yao, T.; Larock, R.C. Regio- and stereoselective synthesis of cyclic imidates via electrophilic cyclization of 2-(1-alkynyl)benzamides. A correction. J. Org. Chem., 2012, 77(23), 10938-10944.
[http://dx.doi.org/10.1021/jo301958q] [PMID: 23110553]
(c) Schlemmer, C.; Andernach, L.; Schollmeyer, D.; Straub, B.F.; Opatz, T. Iodocyclization of o-alkynylbenzamides revisited: Formation of isobenzofuran-1(3H)-imines and 1H-isochromen-1-imines instead of lactams. J. Org. Chem., 2012, 77(22), 10118-10124.
[http://dx.doi.org/10.1021/jo3017378] [PMID: 23088716]
[http://dx.doi.org/10.1039/C8OB00779A] [PMID: 29873384]
(b) Wang, Y-H.; Ouyang, B.; Qiu, G.; Zhou, H.; Liu, J-B. Oxidative oxy-cyclization of 2-alkynylbenzamide enabled by TBAB/Oxone: Switchable synthesis of isocoumarin-1-imines and isobenzofuran-1-imine. Org. Biomol. Chem., 2019, 17(17), 4335-4341.
[http://dx.doi.org/10.1039/C9OB00320G] [PMID: 30976768]
[http://dx.doi.org/10.1002/ejoc.201900321]
[http://dx.doi.org/10.1021/acs.joc.9b01643] [PMID: 31436089]
[http://dx.doi.org/10.1002/ejoc.201600018]
(b) Liang, H.; Ji, Y-X.; Wang, R-H.; Zhang, Z-H.; Zhang, B. Visible-light-initiated manganese-catalyzed E-selective hydrosilylation and hydrogermylation of alkynes. Org. Lett., 2019, 21(8), 2750-2754.
[http://dx.doi.org/10.1021/acs.orglett.9b00701] [PMID: 30931573]
(c) Allen, B.D.W.; Hareram, M.D.; Seastram, A.C.; McBride, T.; Wirth, T.; Browne, D.L.; Morrill, L.C. Manganese-catalyzed electrochemi-cal deconstructive chlorination of cycloalkanols via alkoxy radicals. Org. Lett., 2019, 21(22), 9241-9246.
[http://dx.doi.org/10.1021/acs.orglett.9b03652] [PMID: 31687826]
(d) Liu, W.; Groves, J.T. Manganese-catalyzed oxidative benzylic C-H fluorination by fluoride ions. Angew. Chem. Int. Ed. Engl., 2013, 52(23), 6024-6027.
[http://dx.doi.org/10.1002/anie.201301097] [PMID: 23616443]