Asymmetric Synthesis of Amino-Bis-Pyrazolone Derivatives via an Organocatalytic Mannich Reaction



: Chauhan P, Mahajan S, Kaya U, Peuronen A, Rissanen K, Enders D

Publisher: AMER CHEMICAL SOC

: 2017

: Journal of Organic Chemistry

: JOURNAL OF ORGANIC CHEMISTRY

: J ORG CHEM

: 82

: 13

: 7050

: 7058

: 9

: 0022-3263

DOI: https://doi.org/10.1021/acs.joc.7b01113


A new series of N-Boc ketimines derived from pyrazolin-5-ones have been used as electrophiles in asymmetric Mannich reactions with pyrazolones. The amino-bis-pyrazolone products are obtained in excellent yields and stereo-selectivities by employing a very low loading of 1 mol % of a bifunctional squaramide organocatalyst. Depending on the substitution at position 4 of the pyrazolones, the new protocol allows for the generation of one or two tetrasubstituted stereocenters, including a one-pot version combing the Mannich reaction with a base-mediated halogenation.



Last updated on 2024-26-11 at 10:29