Ligand-Free, Copper-Catalyzed Aerobic Benzylic sp³ C–H Oxygenation

Abstract

A ligand-free and operationally simple copper-catalyzed aerobic benzylic sp³ C–H oxygenation was developed. The addition of tert-butyl hydroperoxide, either in a catalytic or stoichiometric amount, was key for activating stable C–H bonds under mild conditions to furnish the corresponding ketones or esters in moderate to excellent yield.

Key words

sp³ C–H oxygenation - copper - oxygen - ligand-free - benzylic oxidation

• References and Notes

• 1a Yang L. Huang H. Chem. Rev. 2015; 115: 3468
• 1b Wencel-Delord J. Dröge T. Liu F. Glorius F. Chem. Soc. Rev. 2011; 40: 4740
• 1c Liu C. Yuan J. Gao M. Tang S. Li W. Shi R. Lei A. Chem. Rev. 2015; 115: 12138
• 1d He G. Wang B. Nack WA. Chen G. Acc. Chem. Res. 2016; 49: 635
• 1e Brückl T. Baxter RD. Ishihara Y. Baran PS. Acc. Chem. Res. 2012; 45: 826
• 1f Newhouse T. Baran PS. Angew. Chem. Int. Ed. 2011; 50: 3362
• 1g Osberger TJ. Rogness DC. Kohrt JT. Stepan AF. White MC. Nature 2016; 537: 214
• 1h Neufeldt SR. Sanford MS. Acc. Chem. Res. 2012; 45: 936
• 1i Chen MS. White MC. Science 2007; 318: 783
• 1j White MC. Science 2012; 335: 807
• 2a Zhu X. Chiba S. Chem. Soc. Rev. 2016; 45: 4504
• 2b Guo X.-X. Gu D.-W. Wu Z. Zhang W. Chem. Rev. 2015; 115: 1622
• 2c Gunasekarana N. Adv. Synth. Catal. 2015; 357: 1990
• 2d Iosub AV. Stahl SS. ACS Catal. 2016; 6: 8201
• 2e Klussmann M. Schweitzer-Chaput B. Synlett 2016; 27: 190
• 3a Güell I. Ribas X. Eur. J. Org. Chem. 2014; 3188
• 3b Hussain I. Capricho J. Yawerc MA. Adv. Synth. Catal. 2016; 358: 3320
• 3c Corcoran EB. Pirnot MT. Lin S. Dreher SD. DiRocco DA. Davies IW. Buchwald SL. MacMillan DW. C. Science 2016; 355: 279

Representative examples for Cr:
• 4a Chung A. Miner MR. Richert KJ. Rieder CJ. Woerpel KA. J. Org. Chem. 2015; 80: 266

Representative examples for Co:
• 4b da Silva MJ. Robles-Dutenhefner P. Menini L. Gusevskaya EV. J. Mol. Catal. A: Chem. 2003; 201: 71
• 4c Pei L. Alper H. J. Mol. Catal. 1992; 72: 143

Representative examples for Cu:
• 4d Li J. Zhang X. Yi H. Liu C. Liu R. Zhang H. Zhuo K. Lei A. Angew. Chem. Int. Ed. 2015; 54: 1261
• 4e Yu J.-W. Mao S. Wang Y.-Q. Tetrahedron Lett. 2015; 56: 1575
• 4f Xu W. Jiang Y. Fu H. Synlett 2012; 23: 801
• 4g De Houwer J. Tehrani KA. Maes BU. W. Angew. Chem. Int. Ed. 2012; 51: 2745

Representative examples for Mo:
• 4h Murphy EF. Schneider M. Mallat T. Baiker A. Synthesis 2001; 547

Representative examples for Fe:
• 4i Miao C. Zhao H. Zhao Q. Xia C. Sun W. Catal. Sci. Technol. 2016; 6: 1378

Transition-metal-free conditions:
• 4j Tada N. Ban K. Yoshida M. Hirashima S.-i. Miura T. Itoh A. Tetrahedron Lett. 2010; 51: 6098
• 4k Ishii Y. Nakayama K. Takeno M. Sakaguchi S. Iwahama T. Nishiyama T. J. Org. Chem. 1995; 60: 3934
• 4l Rusch F. Schober J.-C. Brasholz M. ChemCatChem 2016; 8: 2881
• 4m Ren L. Wang L. Lv Y. Gao S. Org. Lett. 2015; 17: 2078
• 4n Dos Santos A. Kaim LE. Grimaud L. Org. Biomol. Chem. 2013; 11: 3282
• 4o Zhang X. Ji X. Jiang S. Liu L. Weeks BL. Zhang Z. Green Chem. 2011; 13: 1891
• 4p Wang H. Wang Z. Huang H. Tan J. Xu K. Org. Lett. 2016; 18: 5680
• 4q Zhang Z. Gao Y. Liu Y. Li J. Zie H. Li H. Wang W. Org. Lett. 2015; 17: 5492
• 4r Ma J. Hu Z. Li M. Zhao W. Hu X. Mo W. Hu B. Sun N. Shen Z. Tetrahedron 2015; 71: 6733
• 4s Yi H. Bian C. Hu X. Niu L. Lei A. Chem. Commun. 2015; 51: 14046
• 5a Jiang JA. Chen C. Huang JG. Liu HW. Cao S. Ji YF. Green Chem. 2014; 16: 1248
• 5b Romano AM. Ricci M. J. Mol. Catal. A: Chem. 1997; 120: 71
• 5c Sterckx H. Houwer JD. Mensch C. Caretti I. Tehrani KA. Herrebout WA. Doorslaer SV. Maes BU. W. Chem. Sci. 2016; 7: 346
• 5d Liu J. Zhang X. Yi H. Liu C. Liu R. Zhang H. Zhuo K. Lei A. Angew. Chem. Int. Ed. 2015; 54: 1261
• 5e Zhang L. Ang GY. Chiba S. Org. Lett. 2011; 13: 1622
• 5f Hayashi Y. Komiya N. Suzuki K. Murahashi S. Tetrahedron Lett. 2013; 54: 2706
• 5g Yu J.-W. Mao S. Wang Y.-Q. Tetrahedron Lett. 2015; 56: 1575
• 5h Wang Y.-F. Zhang F.-L. Chiba S. Synthesis 2012; 44: 1526
• 6 Cu-Catalyzed Aerobic C–H Oxygenation of 1a; Typical Procedure: To a test tube charged with CuCl (2.0 mg, 0.02 mmol) and isochroman (1a; 251 μL, 2.0 mmol) in t-BuOH (20 mL) was added TBHP (5.0–6.0 M in decane, 10.9 μL, 0.6 mmol) and the mixture was stirred and heated at 50 °C for 12 h under open air. After cooling to room temperature, the reaction was quenched with 25% aqueous ammonia solution and water then the mixture was extracted with EtOAc. The separated organic layer was dried over Na₂SO₄ and products were concentrated after filtration. The residue was purified by silica gel column chromatography (EtOAc/hexane, 1:10) to give isochromanone (2a) as a colorless oil in 83% yield.

NMR data of all products were consistent with previously reported data.
• 7a For 2a–e: Dohi T. Takenaga N. Goto A. Fujioka H. Kita Y. J. Org. Chem. 2008; 73: 7365
• 7b For 2g, 2b, and 2c: Komagawa H. Maejima Y. Nagano T. Synlett 2016; 27: 789
• 7c For 2f: Zhao B. Lu X. Org. Lett. 2006; 8: 5987
• 7d For 2h: Mineno T. Nikaido N. Kansui H. Chem. Pharm. Bull. 2009; 57: 1167
• 7e For 2i: Gao HY. Ha CY. Synth. Commun. 2006; 36: 3283
• 7f For 2k: Yanai H. Taguchi T. Chem. Commun. 2012; 48: 8967
• 7g For 2j: Kinder MA. Kopf J. Margaretha P. Tetrahedron 2000; 56: 6763
• 7h For 2l, 2m, 2n, and 2o: Zhang Z. Gao Y. Liu Y. Li J. Xie H. Li H. Wang W. Org. Lett. 2015; 17: 5492
• 7i For 2p: Kobayashi K. Kondo Y. Org. Lett. 2009; 11: 2035
• 7j For 2q: Yamamoto Y. Hasegawa H. Yamataka H. J. Org. Chem. 2011; 76: 4652
• 7k For 3: Catino AJ. Nichols JM. Choi H. Gottipamula S. Doyle MP. Org. Lett. 2005; 7: 5167
• 8 Boess E. Wolf LM. Malakar S. Salamone M. Bietti M. Thiel W. Klussmann M. ACS Catal. 2016; 6: 3253
• 9 Boess E. Schmitz C. Klussmann M. J. Am. Chem. Soc. 2012; 134: 5317
• 10 Mukaiyama T. Miyoshi N. Kato J. Ohshima M. Chem. Lett. 1986; 1385
• 11 For a review of organic peroxide rearrangement, see: Yaremenko IA. Vil VA. Demchuk DV. Terentev AO. Beilstein J. Org. Chem. 2016; 12: 1647