Low catalyst loading enabled organocatalytic synthesis of chiral bis-heterocyclic frameworks containing pyrazole and isoxazole

Abstract

A low-catalyst loading Michael addition reaction of pyrazolyl nitroalkenes with 1,3-dicarbonyl derivatives has been carried out under mild reaction conditions to afford 4-substituted pyrazole derivatives in 60-87% yields and 82-96% ee. These pyrazolyl derivatives are further transformed into chiral bis-heterocyclic derivatives in up to 82% yields and up to 99% ee. The synthesized pyrazole and isoxazole based bis-heterocyclic derivatives are potential bio-active molecules expected to have significant applications. Additionally, synthesis of these bis-heterocycles can efficiently be carried out in one-pot without any loss of enantiopurity, which further adds to its significance.