Facile and Selective Oxidation of Benzylic Alcohols to Their Corresponding Carbonyl Compounds with Sodium Nitrate in the Presence of Brønsted Acidic Ionic Liquids

Abstract

A chemoselective and effective procedure for the conversion of benzylic and allylic alcohols into the corresponding ­carbonyl compounds using sodium nitrate-3-methylimidazolinium hydrogensulfate is reported.

Key words

Brønsted acidic ionic liquids - oxidation - alcohols - aldehydes - ketones

References and Notes

• 1 Mehdi H. Bodor A. Lantos D. Horvath IT. De Vos DE. Binnemans K. J. Org. Chem.  2007,  72:  517 
• 2 Welton T. Chem. Rev.  1999,  99:  2071 
• 3 Earle MJ. McCormac PB. Seddon KR. Chem. Commun.  1998,  2245 
• 4 Liu F. Abrams MB. Baker RT. Tumas W. Chem. Commun.  2001, 
• 5 Bates ED. Mayton RD. Ntai I. Davis JH. J. Am. Chem. Soc.  2002,  124:  926 
• 6 Zhu HP. Yang F. Tang J. He MY. Green Chem.  2003,  5:  38 
• 7 Wu HH. Yang F. Pg C. Tang J. He MY. Tetrahedron Lett.  2004,  45:  4963 
• 8 Driver G. Johnson KE. Green Chem.  2003,  5:  163 
• 9 Hajipour AR. Mallakpour SE. Khoee S. Synlett  2000,  740 
• 10 Cornelis A. Herze P. Laszlo P. Tetrahedron Lett.  1982,  23:  5035 
• 11 Li C. Xu Y. Lu M. Zhao Z. Liu L. Zhao Z. Cui Y. Zheng P. Ji X. Gao G. Synlett  2002,  2041 
• 12 Gasparrini F. Giovannoli M. Misiti D. Natile G. Palmieri G. Synth. Commun.  1988,  18:  69 
• 13 Strazzolini P. Runcio A. Eur. J. Org. Chem.  2003,  526 
• 14 Barrett AGM. Braddock DC. McKinnell RM. Waller FJ. Synlett  1999,  1489 
• 15 Lee JC. Lee JY. Lee JM. Bull. Korean Chem. Soc.  2005,  26:  1300 
• 16a Hajipour AR. Mallakpour SE. Imanzadeh G. J. Chem. Res., Synop.  1999,  228 
• 16b Hajipour AR. Mallakpour SE. Adibi H. Chem. Lett.  2000,  460 
• 16c Hajipour AR. Mallakpour SE. Afrousheh A. Tetrahedron  1999,  55:  2311 
• 16d Hajipour AR. Islami F. Indian J. Chem., Sect. B: Org. Chem. Incl. Med. Chem.  1999,  38:  461 
• 16e Hajipour AR. Mallakpour SE. Imanzadeh G. Chem. Lett.  1999,  99 
• 16f Hajipour AR. Hantehzadeh M. J. Org. Chem.  1999,  64:  8475 
• 16g Hajipour AR. Mallakpour SE. Backnejad H. Synth. Commun.  2000,  30:  3855 
• 16h Hajipour AR. Mallakpour SE. Afrousheh A. Phosphorus, Sulfur Silicon Relat. Elem.  2000,  160:  67 
• 16i Hajipour AR. Mallakpour SE. Khoee S. Chem. Lett.  2000,  120 
• 16j Hajipour AR. Mohammadpoor-Baltork I. Nikbaghat K. Imanzadeh Gh. Synth. Commun.  1999,  29:  1697 
• 17 Hajipour AR. Mahboubkhah N. J. Chem. Res., Synop.  1998,  122 
• 18a Mohammadpoor-Baltork I. Hajipour AR. Mohammadi H. Bull. Chem. Soc. Jpn.  1998,  16:  71 
• 18b Hajipour AR. Mahboubkhah N. Synth. Commun.  1998,  28:  3143 
• 18c Hajipour AR. Mohammadpoor-Baltork I. Kianfar G. Bull. Chem. Soc. Jpn.  1998,  71:  2655 
• 18d Hajipour AR. Mohammadpoor-Baltork I. Kianfar G. Indian J. Chem., Sect. B: Org. Chem. Incl. Med. Chem.  1998,  37B:  607 
• 18e Hajipour AR. Mahboubkhah N. Org. Prep. Proced. Int.  1999,  31:  112 
• 18f Hajipour AR. Mohammadpoor-Baltork I. Niknam K. Org. Prep. Proced. Int.  1999,  31:  335 
• 18g Mohammadpoor-Baltork I. Hajipour AR. Haddadi R. J. Chem. Res., Synop.  1999,  102 
• 18h Hajipour AR. Mallakpour SE. Samimi HA. Synlett  2001,  1735 
• 19 Hajipour AR. Ruoho AE. Org. Prep. Proced. Int.  2005,  37:  279 
• 20 Hajipour AR. Adibi H. Ruoho AE. J. Org. Chem.  2003,  68:  4553 
• 23 Mudgal PK. Bansal SP. Gupta KS. Atmos. Environ.  2007,  accepted for publication

21

Preparation of [Hmim]⁺HSO₄ ^-: 1-methylimidazole (0.82 g, 0.01 mol) was placed in a two-necked flask with stirrer and was cooled to 0 °C. MeCN (10 mL) was added and then H₂SO₄ (0.98 g, 0.01 mol) was added slowly with stirring. The mixture was stirred for 30 min and the MeCN was removed by simple decanting.

22

General procedure: In a mortar a mixture of benzylic alcohol (1.0 mmol), sodium nitrate (0.085 g, 1.0 mmol), and [Hmim]⁺HSO₄ ^- (0.25 mmol) was ground with a pestle. The reaction times and temperatures are shown in Table [1] . After completion of the reaction (monitored by TLC, EtOAc-cyclohexane, 25:75), the mixture was cooled to r.t., extracted into Et₂O and washed with H₂O. The organic layer was dried over Na₂SO₄ and evaporated under reduced pressure. Purification of the residue using flash column chromatography (silica gel, EtOAc-cyclohexane, 20:80) provided the pure carbonyl compounds.