Platinum-catalyzed consecutive C–N bond formation-[1,3] shift of carbamoyl and ester groups

The reaction of ortho-alkynylphenylureas 1 having a carbamoyl group attached to the nitrogen atom proceeded in the presence of catalytic amounts of PtI4, affording corresponding indole-3-carbamides 2 in moderate to high yields. In addition, the platinum-catalyzed cyclization of ortho-alkynylphenyl carbamates 3 afforded corresponding indole-3-carboxylates 4 in good yields. The present reaction proceeds through the intramolecular addition of carbon–nitrogen bonds to triple bonds, the so-called carboamination.