An efficient synthetic method of 1,3-bis(arylethynyl)isobenzofurans is developed. Nucleophilic addition of alkynyllithium to benzocyclobutenone and subsequent oxidative ring cleavage of the four-membered ring gave a keto-aldehyde, which, in turn, accepted the second nucleophile to produce isobenzofurans after acid treatment.
An efficient generation method of didehydroisobenzofuran, a new heteroaryne species, was developed by bromine/lithium exchange of the dibromoisobenzofuran. The reactive intermediate, thus generated, was trapped by appropriate arynophile to give the [2+2], [2+3], and [2+4] cycloadducts, respectively. Moreover, the reaction could be applied to the syntheses of isoanthracenofurans (anthra[2,3‐c]furans), a new class of heteroacenes, with isoelectoronic structure to the corresponding acenoheteroles (anthra[2,3‐b]furans).
The nucleophilic addition of in situ generated alkynyllithiums to benzocyclobutenone (V) followed by an oxidative ring cleavage affords aldehydes (VIII), which are converted into desired symmetrical and unsymmetrical 1,3‐bis(arylethynyl)isobenzofurans (X) and (XII).
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