The acid-promoted reactions of phenyliodonium ylides with substituted anilines and their applications to the synthesis of indoles.

The N-substituted anilines 1 react readily with phenyliodonium ylides 2 derived from 1,3-dicarbonyl compounds in the presence of a catalytic amount of BF(3).Et(2)O, forming the C-N coupling products 3, which are precursors for the synthesis of indoles. On the basis of this result, the direct synthesis of indoles from 1 and 2 under thermal conditions and photochemical conditions was explored. The transformations could be achieved in a one-pot way under thermal conditions or in a tandem manner under photochemical conditions.