One-pot stereoselective synthesis of trifluoromethylated penta(2Z,4E)-dieneniariles via double olefination

A novel double olefination via sequential transformation of diethyl (1-cyan oethyl)phosphonate and its application to the synthesis of substituted trif luoromethylated pentadienenitriles with 2Z,4E-isomers formed exclusively in 71-85% yield are described. This reaction is of broad scope since R may be alkyl, aryl or a heterocyclic group. The configuration of the products was ascertained on the basis of X-ray crystallographic analysis. The stereoche mical results are rationalized by the proposed mechanism.