Tandem Catalytic Carbene Addition/Bicyclization of Enynes. One-Step Synthesis of Fluorinated Bicyclic Amino Esters by Ruthenium Catalysis

The reaction of diazo compounds with enynes, containing a fluorinated amino acid moiety, in the presence of the precatalyst Cp*(Cl)Ru(COD) leads to fluorinated alkenyl bicyclo[3.1.0]hexane and [4.1.0]heptane amino acid derivatives. It is remarkable that the catalyst, in situ generated from ruthenium complex and diazo compound, completely inhibits the ring closing metathesis of enyne to the profit of tandem alkenylation/cyclopropanation with high stereoselectivity. The study shows that the Cp*(Cl)Ru moiety in ruthenacyclobutane favors reductive elimination versus expected alkene metathesis.