Dibromoisobenzofuran as a Formal Equivalent of Didehydroisobenzofuran: Reactive Platform for Expeditious Assembly of Polycycles
摘要:
Two-directional annulation of dibromoisobenzofuran, a formal equivalent to didehydroisobenzofuran, was developed. Importantly, selective bromine lithium exchange allows the tandem generation of benzynes and dual cycloadditions with two different arynophiles. Also described is the application to the synthesis of a substituted pentacene.
A new synthetic route to substituted tetracenes and pentacenes via stereoselective [4+2] cycloadditions of 1,4-dihydro-1,4-epoxynaphthalene and isobenzofuran
Stereoselective [4+2] cycloadditions of 1,4-dihydro-1,4-epoxynaphthalene and isobenzofuran were described. Among several possibilities, syn-exo and/or anti-endo isomers were selectively produced depending on the substitution pattern of the reactants. Importantly, the syn-exo isomer underwent acid promoted aromatization, affording the corresponding tetracene. These findings enabled us to prepare a substituted