Tandem Cyclopropanation/Vinylogous Cloke–Wilson Rearrangement for the Synthesis of Heterocyclic Scaffolds

Cyclopropanation of 1,3-dienes with ethyl 2-formyldiazoacetate under rhodium catalysis results in either a tandem cyclopropanation/Cloke–Wilson rearrangement or a vinylogous variant, depending on the diene used. These adducts may be subjected to an oxygen to nitrogen substitution with various amines under palladium catalysis. The substrate scope and mechanistic reasoning is presented.