Regioselective Synthesis of Polyheterohalogenated Naphthalenes via the Benzannulation of Haloalkynes

Independent control of halide substitution at six of the seven naphthalene positions of 2-arylnaphthalenes is achieved through the regioselective benzannulation of chloro-, bromo-, and iodoalkynes. The modularity of this approach is demonstrated through the preparation of 44 poly-heterohalogenated naphthalene products, most of which are difficult to access through known naphthalene syntheses. The outstanding regioselectivity of the reaction is both predictable and proven unambiguously by single-crystal Xray diffraction for many examples. This synthetic method enables the rapid preparation of complex aromatic systems poised for further derivatization using established cross-coupling methods. The power and versatility of this approach makes substituted naphthalenes highly attractive building blocks for new organic materials and diversity-oriented synthesis.