Preparation of 2-(N,N-dialkylamino)-2,4,6- cycloheptatrien-1-one derivatives from an isocyanide, a primary amine, propionaldehyde, and tropolone via Ugi-Smiles coupling reaction in the presence of silica nanoparticles

The use of Smiles rearrangement in Ugi-type couplings with tropolone allows very straightforward multicomponent formation of 2-(N ,N-dialkylamino)-2,4,6-cycloheptatrien-1-one derivatives. The 4-component reaction of isocyanides, tropolone (2-hydroxy-2,4,6-cycloheptatrien-1-one), primary amines, and propionaldehyde in the presence of silica nanoparticles (silica NPs, ca. 42 nm) proceeds easily in methanol to form the title compounds in a new Ugi–Smiles-type reaction.