A Facile Synthesis of Highly Functionalized Unsymmetrical Heterobiaryls Utilizing the Intramolecular Ullmann Coupling Reaction Directed by Salicyl Alcohol as a Template

The cyclic heterobiaryls (3) containing a thenoyl or furoyl group were synthesized in good yields by regioselective acylations of salicyl alcohol (1), followed by the intramolecular Ullmann coupling reaction of the diesters (2). The cleavage of the two ester bonds of 3 by hydrogenolysis or nucleophilic substitution reactions proceeded regioselectively to afford the highly functionalized unsymmetrical heterobiaryls (4-6) in good yields