Ring Opening of Donor-Acceptor Cyclopropanes with Cyanide Ion and Its Surrogates

A straightforward method for ring opening of donor-acceptor cyclopropanes with trimethylsilyl cyanide as a surrogate of cyanide ion in the presence of B(C6F5)(3) or trifluoromethanesulfonic acid as a catalyst has been developed. The methodology provides a short route to gamma-cyanoesters that can be useful synthetic intermediates for the synthesis of diverse bioactive molecules such as glutaric and delta-aminovaleric acid derivatives, 3-arylpiperidines, or other substituted phenethylamines. Oppositely, the attempts to synthesize these gamma-cyanoesters by direct reaction of cyclopropanes with sodium cyanide under typical S(N)2 conditions led to the formation of 2-arylsuccinonitriles.