Friedel−Crafts‐Type Allylation of Phenol Derivatives Catalyzed by In Situ‐Generated Silyl Cyanometallates

Abstract

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.

Ag-Catalyzed Cyanomethylation of Amines Using Nitromethane as a C1 Source

“…We have already reported that a silyl cyanometallate complex (Me 3 Si)­[Ag­(CN) 2 ] was reversibly generated by the reaction of a silver salt and excess amount of Me 3 SiCN . The complex functioned as a stronger silyl Lewis acid than the less polarized Me 3 SiCN …”

“…15 The complex functioned as a stronger silyl Lewis acid than the less polarized Me 3 SiCN. 16 In situ generated 7a acts as a precursor of iminium B under the acidic conditions, and it accepts cyanide ( − CN) through Strecker-like reaction mechanisms to afford the cyanomethylated product 2a.…”