A rhodium-catalyzed direct C−H arylation of naphthalene and anthracene was developed with the assistance of a thioether directing group. The reaction proceeded with exclusive peri-selectivity, and the series of coupling products were readily transformed into the corresponding sulfur-containing polyaromatics. Charge-transport properties of the provided dithiapyrenes were evaluated by computational studies.

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A benzo [b]thiophene synthesis by Rhcatalyzed three-component coupling reaction of arylboronic acids, alkynes, and elemental sulfur (S 8 ) is developed. A notable feature of this protocol is that the thienannulation (thiophene annulation) proceeds with high regioselectivity via the sequential alkyne insertion, CÀ H activation, and then sulfur atom transfer to the metallacycle intermediate. In a similar manner, dibenzothiophenes can be synthesized from the parent biarylboronic acids and S 8 .

A rhodium-catalyzed oxidative annulation of benzimidates with elemental sulfur for the direct construction of isothiazole rings is reported. The proposed reaction mechanism involving Rh­(I)/Rh­(III) redox is supported by a stoichiometric reaction of metallacycle species as well as DFT calculations. This method is also applicable to selenium cyclization to produce isoselenazole derivatives. The alkoxy substituent at C3 can be used for further functionalization of the azole core.

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