Visible-Light-Driven Oxidative Mono- and Dibromination of Benzylic­ sp³ C–H Bonds with Potassium Bromide/Oxone at Room Temperature

^◊ M.Z. and M.L. contributed equally to this work.

Abstract

Benzylic sp³ C–H bonds have been successfully brominated with potassium bromide by using Oxone as an oxidant in water/dichloromethane under visible light at room temperature. Toluene, ethylbenzene and other alkylbenzenes bearing an electron-withdrawing group, such as Br, Cl, COMe, CO₂Et, CO₂H, CN or NO₂, provide the corresponding benzylic monobromides in good to excellent yields in this reaction. Dibromides can also be produced in the presence of excess potassium bromide in a prolonged reaction time. Control of the illuminance of visible light (~500 lux) is crucial to achieving both high yield and high selectivity in these brominations. Mono- and difluorides can be conveniently prepared through nucleophilic substitutions of the benzylic bromides with potassium fluoride.

Key words

benzylic C–H bond - bromination - oxidation - photochemistry - room temperature

• References

• 1a Lin R. Amrute AP. Pérez-Ramírez J. Chem. Rev. 2017; 117: 4182
• 1b Lu W. Zhou L. Oxidation of C–H Bonds . John Wiley & Sons, Inc; Hoboken: 2017
• 1c Shimojo H. Moriyama K. Togo H. Synthesis 2015; 47: 1280
• 2a Djerassi C. Chem. Rev. 1948; 43: 271
• 2b Huyser ES. J. Am. Chem. Soc. 1960; 82: 391
• 2c Avramoff M. Weiss J. Schächter O. J. Org. Chem. 1963; 28: 3256
• 2d Shaw H. Perlmutter HD. Gu C. Arco SD. Quibuyen TO. J. Org. Chem. 1997; 62: 236
• 2e Kikuchi D. Sakaguchi S. Ishii Y. J. Org. Chem. 1998; 63: 6023
• 2f Smirnov VV. Zelikman VM. Beletskaya IP. Levitskii MM. Kazankova MA. Mendeleev Commun. 2000; 10: 175
• 2g Shibatomi K. Zhang Y. Yamamoto H. Chem. Asian J. 2008; 3: 1581
• 2h Nishina Y. Hashimoto H. Kimura N. Miyata N. Fujii T. Ohtani B. Takada J. RSC Adv. 2012; 2: 6420
• 2i Cantillo D. de Frutos O. Rincon JA. Mateos C. Kappe CO. J. Org. Chem. 2014; 79: 223
• 3a Podgoršek A. Zupan M. Iskra J. Angew. Chem. Int. Ed. 2009; 48: 8424
• 3b Amati A. Dosualdo G. Zhao L. Bravo A. Fontana F. Minisci F. Bjørsvik HR. Org. Process Res. Dev. 1998; 2: 261
• 3c Podgoršek A. Stavber S. Zupan M. Iskra J. Tetrahedron 2009; 65: 4429
• 3d Yin L. Wu J. Xiao J. Cao S. Tetrahedron Lett. 2012; 53: 4418
• 4a Mataka S. Kurisu M. Takahashi K. Tashiro M. Chem. Lett. 1984; 1969
• 4b Kulangiappar K. Karthik G. Kulandainathan MA. Synth. Commun. 2009; 39: 2304
• 4c Pingali SR. K. Upadhyay SK. Jursic BS. Green Chem. 2011; 13: 928
• 5 Moriyama K. Takemura M. Togo H. Org. Lett. 2012; 14: 2414
• 6a Zhao M. Lu W. Org. Lett. 2017; 19: 4560
• 6b Zhao, M.; Lu, W. unpublished results.
• 7 Cui L. Liu K. Zhang C. Org. Biomol. Chem. 2011; 9: 2258
• 8 Kochergin PM. Bushueva KS. Zh. Obshch. Khim. 1962; 32: 3033
• 9 Snyder HR. Merica EP. Force CG. White EG. J. Am. Chem. Soc. 1958; 80: 4622
• 10 Adimurthy S. Ghosh S. Patoliya PU. Ramachandraiah G. Agrawal M. Gandhi MR. Upadhyay SC. Ghosh PK. Ranu BC. Green Chem. 2008; 10: 232
• 11 Spickett RG. W. Timmis GM. J. Chem. Soc. 1954; 2887
• 12 Soran L. Coman V. Soran A. Silvestru C. Cent. Eur. J. Chem. 2004; 2: 563
• 13 Daub GH. Castle RN. J. Org. Chem. 1954; 19: 1571
• 14 Summers JB. Gunn BP. Martin JG. Martin MB. Mazdiyasni H. Stewart AO. Young PR. Bouska JB. Goetze AM. Dyer RD. Brooks DW. Carter GW. J. Med. Chem. 1988; 31: 1960
• 15 Thiessen W. Wolff T. Des. Monomers Polym. 2011; 14: 287
• 16 Nagarapu L. Apuri S. Gaddam C. Bantu R. Org. Prep. Proced. Int. 2009; 41: 243
• 17 Zysman-Colman E. Arias K. Siegel JS. Can. J. Chem. 2009; 87: 440
• 18 Lambooy JP. J. Am. Chem. Soc. 1950; 72: 2804
• 19 Rogers RB. Herrero MP. EP 101288, 1983
• 20 Xi H. Gibb CL. D. Gibb BC. J. Org. Chem. 1999; 64: 9286
• 21 Di Mola A. Caruso T. De Caprariis P. Massa A. ARKIVOC 2016; (iv): 10
• 22 Makosza M. Owczarczyk Z. J. Org. Chem. 1989; 54: 5094
• 23 Blessley G. Holden P. Walker M. Brown JM. Gouverneur V. Org. Lett. 2012; 14: 2754
• 24 Beguin C. Meary-Tertian A. Bull. Soc. Chim. Fr. 1967; 795
• 25 Aikawa K. Serizawa H. Ishii K. Mikami K. Org. Lett. 2016; 18: 3690