RHODIUM-CATALYZED CARBONYLATION OF 2-ALKYNYLANILINE - SYNTHESES OF 1,3-DIHYDROINDOL-2-ONES

Rhodium-catalyzed carbonylation of 2-alkynylanilines under water-gas s hift reaction conditions gives 3-alkyl-1,3-dihydroindol-2-ones 2 in go od yields along with a small amount of 2-quinolone derivatives 4. The reaction under carbonylation conditions without additive water yields 3-(E)-alkylidene-1,3-dihydroindol-2-ones 3, indicating that the format ion of 2 involves two steps; simultaneous cyclization With carbonylati on of a triple bond by the participation of an adjacent amino group an d subsequent hydrogenation.