Reaction of Baylis–Hillman Adducts with Fluorinated Silanes

Reactions of acylated Baylis–Hillman adducts bearing nitrile, ester, or ketone groups with C 6 F 5 ‐substituted silicon reagents Me n Si(C 6 F 5 ) 4– n ( n = 1–3) have been studied. The reactions are initiated by Bu 4 NOAc (5 mol‐%) in MeCN or DMF under mild conditions and afford products of allylic substitution of the acetoxy group by the C 6 F 5 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 C 6 F 5 carbanion chemoselectively occurred at the C=C bond. Reactions of acylated Baylis–Hillman adducts with Me 3 SiCF 3 were found to be inefficient, as the CF 3 carbanion had the propensity to attack the C=O bond of substrates with ester or ketone substituents.