Zinc-Diethylaluminium Chloride Induced Coupling Reaction of Dibromofluoroacetate with Carbonyl Compounds. New Efficient and Selective Synthesis of α-Bromo-α-fluoro-β-hydroxy and α-Fluoro-β,β'-dihydroxy Esters
Treatment of ethyl dibromofluoroacetate with aldehydes or ketone in the presence of zinc and diethylaluminium chloride at -20 deg C gave rise to the corresponding α-bromo-α-fluoro-β-hydroxy alkanoic acid ethyl esters in good yields, while the use of two equivalents each of aldehyde, zinc, and diethylaluminium chloride in the reaction resulted in a double coupling reaction affording the 1:2 adducts, α-fluoro-β,β'-dihydroxy esters in high yields.