Synthesis of thiocyanato-containing phenanthrenes and dihydronaphthalenes Lewis acid-activated tandem electrophilic thiocyanation/carbocyclization of alkynes.

A tandem electrophilic thiocyanation and cyclization of arene-alkynes has been developed under mild conditions, affording thiocyanato-substituted phenanthrenes, dihydronaphthalenes, 2-chromenes and dihydroquinolines in moderate to excellent yields. This reaction provides an efficient protocol for the construction of C-SCN and C-C bonds in one step. In this transformation, -thiocyanato reagent serves as a convenient precursor to transfer SCN in the presence of trimethylchlorosilane, and the cyclization exhibited exclusive selectivity. Finally, a gram scale reaction and further derivatizations highlight the utility of this synthetic strategy.