Hydrogenation of nitroarenes bearing aldehyde containing side chains over palladium and platinum catalysts: a new route to medium and large heterocyclic compounds

A wide range of nitroarenes bearing aldehyde containing side chains, readily available by hydroformylation of the corresponding alkenes have been hydrogenated over heterogeneous palladium or platinum catalysts to give medium and large heterocycles either resulting from direct cyclisation or by the formation of dimers. The yields of monomers and dimers are discussed as a function of ring size and the pattern of heteroatom substitution in the substrates; in general the greater the number of heteroatoms in the chain, the greater the yield of cyclic compounds.