Didehydroisobenzofuran: A New Reactive Intermediate for Construction of Isoacenofuran.

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).

Catalytic generation of arynes and trapping by nucleophilic addition and iodination.

A fair exchange: in the title reaction, alkynyllithium serves as an initiator for benzyne generation through an iodine-lithium exchange. When performed in the presence of stoichiometric amounts of a nucleophile, the generated benzyne undergoes attack by lithio nucleophiles to generate aryllithium, which is then iodinated by iodoalkyne to give the iodoarenes 1.