New ortho-quinone methide formation: Application to three-component coupling of isocyanides, aldehydes and phenols

A new three - component formation method of heterocyclic scaffolds based on a one - pot process from simple phenols is reported. The important step involved in the process is the formation of ortho - quinon ( o - quinon ) methide under alkyative conditions using Mannich adducts. The transient o - quinon methide has been trapped in situ with indole and diketone using lithium percholate as catalyst. The Mannich addition of phenols has been performed with stoichiometric amounts of amounts of aldehydes either in refluxing toluene or neat at 140 ° C, which constitutes the scheme 1 of the process. Elimination of the piperazine as an insoluble ammonium salt makes that process irreversible. Mannich adduct is prepared to observe intramolecular cycloaddition. This formation reaction is a new general efficient three - component coupling of phenols with aldehydes and various nucleophiles.