Simple H2-free hydrogenation of unsaturated monoterpenoids catalyzed by Raney nickel

A series of monoterpenoids (citral, carvone, menthone, camphor) as well as cyclohexanone and hex-5-en-2-one were subjected to transfer hydrogenation with PrⁱOH/Raney nickel system at 82 or 150°C. Among monoterpenoids, citral and carvone underwent full conversion at 82°C within 5h.