Iron-Catalyzed Oxidative Arylmethylation of Activated Alkenes Using a Peroxide as the Methyl Source

Abstract

A novel, simple route for the synthesis of oxindoles is presented via iron-catalyzed oxidative arylmethylation of activated alkenes with peroxides. This work is realized by the use of a peroxide as the methyl source and 1,4-diazabicyclo[2.2.2]octane as the ligand and represents a new access to oxindoles through an alkene oxidative difunctionalization process.

Key words

iron - alkenes - peroxides - difunctionalization - methylation - oxindoles

• References and Notes


For recent reviews, see:
• 1a Sibbald PA. Palladium-Catalyzed Oxidative Difunctionalization of Alkenes: New Reactivity and New Mechanisms. ProQuest UMI Dissertation Publishing; Cambridge: 2011
• 1b Jacques B, Muiñz K In Catalyzed Carbon–Heteroatom Bond Formation . Yudin AK. Wiley-VCH; Weinheim: 2011: 119-135
• 1c Bergmeier SC. Tetrahedron 2000; 56: 2561
• 1d Beccalli EM, Broggini G, Martinelli M, Sottocornola S. Chem. Rev. 2007; 107: 5318
• 1e Kotov V, Scarborough CC, Stahl SS. Inorg. Chem. 2007; 46: 1910
• 1f Li G, Kotti SR. S. S, Timmons C. Eur. J. Org. Chem. 2007; 2745
• 1g Muñiz K. Angew. Chem. Int. Ed. 2009; 48: 9412
• 1h McDonald RI, Liu G, Stahl SS. Chem. Rev. 2011; 111: 2981
• 1i Xie Y.-X, Song R.-J, Xiang J.-N, Li J.-H. Chin. J. Org. Chem. 2012; 32: 1555
• 1j Zhang C, Tang C, Jiao N. Chem. Soc. Rev. 2012; 41: 3464
• 2 Wu T, Mu X, Liu G.-S. Angew. Chem. Int. Ed. 2011; 50: 12578
• 3a Wei W.-T, Zhou M.-B, Fan J.-H, Liu W, Song R.-J, Liu Y, Hu M, Xie P, Li J.-H. Angew. Chem. Int. Ed. 2013; 52: 3638
• 3b Zhou M.-B, Wang C.-Y, Song R.-J, Liu Y, Wei W.-Y, Li J.-H. Chem. Commun. 2013; 49: 10817
• 3c Zhou M.-B, Song R.-J, Ouyang X.-H, Liu Y, Wei W.-T, Deng G.-B, Li J.-H. Chem. Sci. 2013; 4: 2690
• 4a Meng Y, Guo L.-N, Wang H, Duan X.-H. Chem. Commun. 2013; 49: 7540
• 4b Zhou Z.-Z, Hua H.-L, Luo J.-Y, Chen Z.-S, Zhou P.-X, Liu X.-Y, Liang Y.-M. Tetrahedron 2013; 69: 10030
• 4c Zhou S.-L, Guo L.-N, Wang H, Duan X.-H. Chem. Eur. J. 2013; 19: 12970

For selected papers on the other oxidative C–H fuctionalization/carbocyclization of alkenes, see:
• 5a Jaegli S, Dufour J, Wei H.-L, Piou T, Duan X.-H, Vors J.-P, Neuville L, Zhu J. Org. Lett. 2010; 12: 4498
• 5b Mu X, Wu T, Wang H.-Y, Guo Y.-L, Liu G.-S. J. Am. Chem. Soc. 2012; 134: 878
• 5c Zhang H, Chen P, Liu G.-S. Synlett 2012; 23: 2749
• 5d Wu T, Zhang H, Liu G.-S. Tetrahedron 2012; 68: 5229
• 5e Li Y.-M, Sun M, Wang H.-L, Tian Q.-P, Yang S.-D. Angew. Chem. Int. Ed. 2013; 52: 3972
• 5f Wang H, Guo L.-N, Duan X.-H. Adv. Synth. Catal. 2013; 355: 2222
• 5g Wei X.-H, Li Y.-M, Zhou A.-X, Yang T.-T, Yang S.-D. Org. Lett. 2013; 15: 4158
• 5h Matcha K, Narayan R, Antonchick AP. Angew. Chem. Int. Ed. 2013; 52: 7985
• 5i Xie J, Xu P, Li H.-M, Xue Q.-C, Jin H.-M, Cheng Y.-X, Zhu C.-J. Chem. Commun. 2013; 49: 5672
• 5j Cui Z, Shang X, Shao X.-F, Liu Z.-Q. Chem. Sci. 2012; 3: 2853
• 5k Li Y.-M, Wei X.-H, Li X.-A, Yang S.-D. Chem. Commun. 2013; 49: 1170 ; and references cited therein
• 5l Yang F, Klumphu P, Liang Y.-M, Lipshutz BH. Chem. Commun. 2014; 50: 936
• 6a Zhang Y, Feng J, Li C.-J. J. Am. Chem. Soc. 2008; 130: 2900
• 6b Xia Q.-Q, Liu X.-L, Zhang Y.-J, Chen C, Chen W.-Z. Org. Lett. 2013; 15: 3326

For a special reviews on the methylation reactions, see:
• 7a Schönherr H, Cernak T. Angew. Chem. Int. Ed. 2013; 52: 12256

For selected recent papers, see:
• 7b Zhang S.-Y, Li Q, He G, Nack WA, Chen G. J. Am. Chem. Soc. 2013; 135: 12135
• 7c Kano T, Hayashi Y, Maruoka K. J. Am. Chem. Soc. 2013; 135: 7134
• 7d Zhang S.-Y, He G, Nack WA, Zhao Y.-S, Li Q, Chen G. J. Am. Chem. Soc. 2013; 135: 2124
• 7e Yu D.-G, Wang X, Zhu R.-Y, Luo S, Zhang X.-B, Wang B.-Q, Wang L, Shi Z.-J. J. Am. Chem. Soc. 2012; 134: 14638
• 7f Yao B, Song R.-J, Liu Y, Xie Y.-X, Li J.-H, Wang M.-K, Tang R.-Y, Zhang X.-G, Deng C.-L. Adv. Synth. Catal. 2012; 354: 1890
• 8 Typical Experimental Procedure for the Iron-Catalyzed Oxidative Arylmethylation of Alkenes with Peroxides To a Schlenk tube were added alkenes 1 (0.3 mmol), Fe(OAc)₂ (5 mol%), DABCO (10 mol%), DCP 2d (2 equiv), and DMSO (2 mL). Then the tube was charged with argon and was stirred at 120 °C (oil-bath temp) for the indicated time until complete consumption of starting material as monitored by TLC and GC–MS analysis. After the reaction was finished, the reaction mixture was cooled to r.t., diluted with EtOAc, and washed with brine. The aqueous phase was re-extracted with EtOAc. The combined organic extracts were dried over Na₂SO₄ and concentrated in vacuum, and the resulting residue was purified by silica gel column chromatography (hexane–EtOAc, 20:1) to afford the desired products 3. 3-Ethyl-1,3-dimethylindolin-2-one (3aa)^5d Yield 35.2 mg, 62%; yellow oil. ¹H NMR (400 MHz, CDCl₃): δ = 7.26 (t, J = 6.4 Hz, 1 H), 7.17 (d, J = 7.2 Hz, 1 H), 7.07 (t, J = 7.2 Hz, 1 H), 6.84 (d, J = 8.0 Hz, 1 H), 3.22 (s, 3 H), 1.97–1.89 (m, 1 H), 1.82–1.73 (m, 1 H), 1.35 (s, 3 H), 0.59 (t, J = 7.6 Hz, 3 H). ¹³C NMR (100 MHz, CDCl₃): δ = 180.8, 143.5, 133.9, 127.6, 122.5, 122.4, 107.8, 48.9, 31.4, 26.0, 23.3, 8.8. IR (KBr): 1722, 1461 cm^–1. LRMS (EI, 70 eV): m/z (%) = 189 (21) [M⁺], 161 (100), 190 (6). ESI-HRMS: m/z calcd for C₁₂H₁₆NO [M + H]⁺: 190.1154; found: 190.1161.