One-pot sequential Pauson–Khand reaction – transfer hydrogenation

Abstract

The Pauson–Khand reaction of norbornene (1) and phenylacetylene (2) and subsequent RuCl2(PPh3)3-catalyzed transfer hydrogenation of the resulting enone (3) can be carried out in a one-pot sequence if the base is added after an induction period. The desired ketones (4a, 4b) were obtained in good yield as a mixture of diastereomers (diastereomeric ratio (dr.) 58:42). The relative rates of both the Pauson-Khand reaction and the transfer hydrogenation are decreased by a factor of 2 in the sequence, as compared with the isolated reactions.Key words: Pauson–Khand reaction, transfer hydrogenation.