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Keywords:

  • Fluorine;
  • Silanes;
  • Michael addition;
  • Baylis–Hillman adducts;
  • Chemoselectivity

Abstract

Reactions of acylated Baylis–Hillman adducts bearing nitrile, ester, or ketone groups with C6F5-substituted silicon reagents MenSi(C6F5)4–n (n = 1–3) have been studied. The reactions are initiated by Bu4NOAc (5 mol-%) in MeCN or DMF under mild conditions and afford products of allylic substitution of the acetoxy group by the C6F5 carbanion in good yields. Predominant or exclusive formation of one geometrical isomer was observed in all cases (Z for nitriles, E for esters and ketones). For substrates containing carbonyl groups, nucleophilic attack of the C6F5 carbanion chemoselectively occurred at the C=C bond. Reactions of acylated Baylis–Hillman adducts with Me3SiCF3 were found to be inefficient, as the CF3 carbanion had the propensity to attack the C=O bond of substrates with ester or ketone substituents.