Regioselective synthesis of 1,3,5-tri- and 1,3,4,5-tetrasubstituted pyrazoles from N-arylhydrazones and nitroolefins.
Two general protocols are developed for the regioselective synthesis of 1,3,5-tri- and 1,3,4,5-tetrasubstituted pyrazoles by the reaction of electron-deficient N-arylhydrazones with nitroolefins. Studies on the stereochemistry of the key pyrazolidine intermediate suggest a stepwise cycloaddition mechanism.
Deng
Xiaohu
X
Johnson & Johnson Pharmaceutical Research & Development, L.L.C., 3210 Merryfield Row, San Diego, California 92121, USA. xdeng@prdus.jnj.com
Mani
Neelakandha S
NS
D000475:Alkenes / Q000737:chemistry*; D003500:Cyclization; D006835:Hydrazones / Q000737:chemistry*; D009574:Nitro Compounds / Q000737:chemistry*; D011720:Pyrazoles / Q000138:chemical synthesis*
D000475:Alkenes; D006835:Hydrazones; D009574:Nitro Compounds; D011720:Pyrazoles