Phenylation Reaction of α-Acylnitromethanes To Give 1,2-Diketone Monooximes: Involvement of Carbon Electrophile at the Position α to the Nitro Group

Abstract

The generality and the effects of substituents on phe­nylation reactions of α-acylnitromethanes catalyzed by trifluoromethanesulfonic acid have been studied. α-Aroylnitromethanes afforded benzil monooximes in good yield. In the case of aliphatic α-acylnitromethane, a similar phenylation reaction proceeded, but the yield of the phenylated 1,2-dione monooxime was low. These phenylation reactions represent examples of the generation of carbocation electrophiles at the α-position of a nitro group.

Key words

α-ketonitromethane - 1,2-dione monooxime - electrophilic aromatic substitutions - umpolung - protonation

References

• 1 Rosini G. In Comprehensive Organic Synthesis   Vol. 2:  Heathcock CH. Pergamon Press; Oxford: 1991.  Chap. 1.10. p.321 
• 2a Hawthorne MF. J. Am. Chem. Soc.  1957,  79:  2510 
• 2b Kornblum N. Brown RA. J. Am. Chem. Soc.  1965,  87:  1742 
• 2c Kornblum N. Brown RA. J. Am. Chem. Soc.  1964,  86:  2681 
• 2d Edward JT. Tremaine PH. Can. J. Chem.  1971,  49:  3483 
• 3 Ohwada T. Yamagata N. Shudo K. J. Am. Chem. Soc.  1991,  113:  1364 
• 4 Kearney T. Harris PA. Jackson A. Joule JA. Synthesis  1992,  769 
• 5 Katritzky AR. Zhang Y. Singh SK. Synthesis  2003,  2795 
• 6 Katritzky AR. Abdel-Fattah AAA. Gromova AV. Witek R. Steel PJ. J. Org. Chem.  2005,  70:  9211 
• 7a Coustard J.-M. Jacquesy J.-C. Violeau B. Tetrahedron Lett.  1991,  32:  3075 
• 7b Coustard J.-M. Jacquesy J.-C. Violeau B. Tetrahedron Lett.  1992,  33:  8085 
• 7c Shimizu T. Hayashi Y. Teramura K. Bull. Chem. Soc. Jpn.  1985,  58:  2519 
• 8 McMurry J. Melton J. J. Org. Chem.  1973,  38:  4367 

9

Detection of ^¹H-NOE between the CH₃ group and the aromatic ortho-protons supported the assignment of the E-geometry of the olefin of 6b.

10

The reaction of 2a also proceeded with substituted benzenes, p-xylene and anisole, to give the corresponding oximes in comparable yields (see ref 3).