BF3.Et2O-catalyzed direct carbon-carbon bond formation of alpha-EWG Ketene-(S,S)-acetals and alcohols and synthesis of unsymmetrical biaryls

A highly efficient BF3.OEt2-catalyzed formal dehydration C-C coupling reaction between readily available alpha-EWG ketene-(S,S)-acetals and various alcohols via direct substitution of the hydroxy group in alcohols has been developed. On the basis of this C-C coupling reaction, a series of alkylated alpha-EWG ketene-(S,S)-acetals and functionalized 1,4-pentanedienes were prepared in high to excellent yields and the unsymmetrical biaryls were synthesized in good yields from the generated 1,4-pentanedienes and nitroalkanes through a one-pot annulation-aromatization process.