We successfully demonstrated that Friedel−Crafts‐type allylation of phenol derivatives and allylic phosphates is catalyzed by the AgTFA/trimethylsilyl cyanide (Me3SiCN) and Pd(OAc)2/Me3SiCN combined systems to afford the C‐allylated product in a highly regioselective manner. The corresponding silyl cyanometallates generated in situ are proposed to be the active catalytic species. Lewis acidity of the reversibly formed ion pairs is appropriately regulated for this reaction. The para‐allylated anisole and phenol derivatives are selectively obtained. The para‐substituted ones are converted to the ortho‐allylated products. The reactivity of the catalytic systems is strongly dependent on the electronic nature of both electrophile and nucleophile. Substitution of an aromatic ring on the allylic phosphate is essential for the reaction. Thus, the competitive reaction of a 1 : 1 mixture of cinnamyl and simple allyl phosphates affords only the cinnamyl‐substituted product.
3-Aryloxindole derivatives were synthesized through the Friedel–Crafts-type cyclization. The reaction was catalyzed by a trimethylsilyl tricyanopalladate complex generated in situ from trimethylsilyl cyanide and Pd(OAc)2. Wide varieties of diethylphosphates derived from N-arylmandelamides were almost quantitatively converted to the oxindols. When N,N;-dibenzylamide was used instead of the anilide substrates, the benzo-fuzed δ-lactam was obtained. The oxindole product was applied to the substitution reactions to afford the 3,3-diaryloxindoles with two different aryl groups.
A new
methodology to afford α-amino nitriles through oxidative
cyanomethylation of amines using nitromethane as the methylene source
in the presence of Me3SiCN without the addition of an external
oxidant was developed. A catalytic amount of AgCN and a stoichiometric
amount of LiBF4 cooperatively promoted the transformation.
A wide variety of the amines, including both aromatic compounds and
aliphatic ones, which are labile under oxidative conditions, were
applicable to the reaction.
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