SYNTHESIS OF FLUORO NITRO ETHERS BY MICHAEL ADDITION-REACTIONS TO ACTIVATED BETA,BETA-DIFLUOROOLEFINS

The ferric chloride catalyzed reaction of isobutyryl chloride with 1,1-difluoroethylene gave l-chloro-l, l-di-fluoro-4-methyl-3-pentanone (1), which was oxidized with m-chloroperbenzoic acid to isopropyl 3-chloro-3,3-difluoropropionate (2). β,β-Difluoroolefms l, l-difluoro-4-methyl-l-penten-3-one (3) and isopropyl 3,3-difluoroacrylate (4) were prepared by dehydrohalogenation of 1 and 2 with amine bases. Unlike their non-fluorinated analogues, 3 and 4 gave no stable Michael adducts with the salts of nitroalkanes, but with β-nitroalcohols such as 2,2-di-nitropropanol (7), fluorodinitroethanol (10), and 2-fluoro-2-nitropropane-l,3-diol (13), the corresponding fluoro nitro ethers were obtained in high yields. Reaction of sodium azide with 1,2, and 2-chloro-2,2-difluoroacetophenone gave l-azido-l,l-difluoro-4-methyl-3-pentanone (17), isopropyl 3-azido-3,3-difluoropropionate (18), and 2-azi-do-2,2-difluoroacetophenone (19). © 1990, American Chemical Society. All rights reserved.