Ring‐Opening Reactions of Donor‐Acceptor Cyclopropanes withEnolizable 5‐Mercapto‐1H‐tetrazoles

Diversely substituted dimethyl 2‐arylcyclopropane‐1,1‐dicarboxylates react under mild conditions, at ambient temperature in the presence of catalytic scandium triflate, with enolizable 5‐meracaptotetrazoles. Most commonly, this yields the corresponding 1:1 adducts via insertion of the S‐atom into the strained C,C bond, leading to ring‐opening. Control experiments performed with dimethyl 2‐phenylcyclopropane‐1,1‐dicarboxylate and 1‐methyl‐5‐mercapto‐1H‐tetrazole demonstrated that the initial product of the reaction is the corresponding sulfane, formed via S‐insertion. However, thermal rearrangement performed at 60 °C led to the formation of the isomeric N‐insertion product. This rearrangement is accelerated by electron‐donating substituents present at the para‐position of the arene. In contrast, electron‐withdrawing substituents prevent this rearrangement at room temperature, and in these examples the S‐insertion products were formed exclusively.