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An Organocatalytic Asymmetric Friedel–Crafts Addition/Fluorination Sequence: Construction of Oxindole–Pyrazolone Conjugates Bearing Vicinal Tetrasubstituted Stereocenters

Organic LettersPublished 16 October 2015
Xiaoze Bao, Baomin Wang, Longchen Cui, Guodong Zhu, Yuli He, Jingping Qü
Citations123
SJR quartileQ1
SJR score1.24
SNIP1.03

TL;DR

This reaction sequence delivers novel oxindole-pyrazolone adducts featuring vicinal tetrasubstituted stereocenters with a 0.5 mol % catalyst loading in high yield with excellent enantio- and diastereocontrol.

Abstract

A highly efficient and practical one-pot sequential process, consisting of an organocatalytic enantioselective Friedel-Crafts-type addition of 4-nonsubstituted pyrazolones to isatin-derived N-Boc ketimines and a subsequent diastereoselective fluorination of the pyrazolone moiety, is developed. This reaction sequence delivers novel oxindole-pyrazolone adducts featuring vicinal tetrasubstituted stereocenters with a 0.5 mol % catalyst loading in high yield with excellent enantio- and diastereocontrol. Notably, chloro, bromo, and thioether functionalities can be readily incorporated, rendering a broad diversity of the product.

Keywords

ChemistryBiochemistry, Genetics and Molecular BiologyPharmacology, Toxicology and Pharmaceutics