The enantioselective synthesis of silicon-stereogenic benzofuranylmethylidene-benzoxasiloles was achieved with moderate enantioselectivity by the cationic rhodium(I)/(S)-BINAP complex-catalyzed desymmetrization of sym. bis(2-ethynylphenol)silanes, possessing the tert-Bu and Me groups on the silicon atom. This reaction involves 1,2-silicon/1,3-carbon migrations and oxycyclization, and the 1,2-silicon migration constructs the stereogenic silicon center. The thus obtained benzofuranylmethylidene-benzoxasiloles with the electron-donating methoxy, Me, and Ph groups on two benzene rings showed good fluorescence quantum yields in soln. state, on the other hand, that with the electron-withdrawing trifluoromethyl groups on two benzene rings showed good fluorescence quantum yield in solid state. [on SciFinder(R)]
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