Process for the preparation of 1,4-diaryl-2-fluoro-4-cyano-2-butenes and intermediates useful therefor

A process for the preparation of a compound of formula I

• wherein
• Ar is phenyl unsubstituted or substituted with any combination of from one to three halogen, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy or C1-C4haloalkoxy groups, or 1- or 2-naphthyl unsubstituted or substituted with any combination of from one to three halogen, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy or C1-C4haloalkoxy groups;
• R is hydrogen, C1-C4alkyl, C1-C4haloalkyl, C3-C6cycloalkyl or C3-C6halocycloalkyl;
• and
• Ar1 is phenoxyphenyl unsubstituted or substituted with any combination of from one to six halogen, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy or C1-C4haloalkoxy groups,
• phenyl unsubstituted or substituted with any combination of from one to five halogen, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy or C1-C4haloalkoxy groups,
• biphenyl unsubstituted or substituted with any combination of from one to five halogen, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy or C1-C4haloalkoxy groups,
• phenoxypyridyl unsubstituted or substituted with any combination of from one to five halogen, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy or C1-C4haloalkoxy groups,
• benzylpyridyl unsubstituted or substituted with any combination of from one to five halogen, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy or C1-C4haloalkoxy groups,
• benzylphenyl unsubstituted or substituted with any combination of from one to five halogen, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy or C1-C4haloalkoxy groups,
• benzoylphenyl unsubstituted or substituted with any combination of from one to five halogen, C1 -C4 alkyl, C1 -C4 haloalkyl, C1 -C4 alkoxy or C1 haloalkoxy groups,
• 1- or 2-naphthyl unsubstituted or substituted with any combination of from one to three halogen, C1-C4alkyl, C1-C4haloalkyl, C1-C4alkoxy or C1-C4haloalkoxy groups;
• or
• the optical isomers thereof;
• or
• the cis and trans isomers thereof,
• which process comprises the following steps:
• a) reacting an intermediate of formula II
• wherein Ar1 is defined as above and X is chloro, bromo, iodo, tosyloxy, mesyloxy or the like with a cyanide delivering reagent in a first solvent to afford a cyano intermediate of formula III
• b) reacting said cyano intermediate III with an aldehyde of formula IV
• in the presence of a base in a second solvent to yield an anion which is acidified to afford a diene of formula V
• c) reacting said diene of formula V with magnesium in the presence of a third solvent to give the desired formula I product.