Abstract

An organocatalytic interrupted three-component Ugi reaction for the synthesis of α,α–diaryl α–amino acid derivatives is described. The transformation proceeds with a range of isocyanides and 3-aryl isoindolinone alcohols using Brønsted acid catalysts to afford products in good to excellent yields. Based on the obtained results, a reaction mechanism is proposed and discussed.

Highlights

  • T HE quaternary carbon stereocenter is a structure that represents a minimalistic molecular framework with enhancedchemical stability and embedded propensity to encode directionality in the three-dimensional space

  • It was reported that rhodium[6] and palladium[7] can catalyze the addition of arylboronic acids to five-membered cyclic N-sulfonyl ketimines substituted with an ester group to give α,α–diaryl α–amino acid derivatives

  • In order to generate α,α–diaryl α–amino acid derivatives, diaryl ketones are required as a carbonyl component

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Summary

INTRODUCTION

T HE quaternary carbon stereocenter is a structure that represents a minimalistic molecular framework with enhanced (bio)chemical stability and embedded propensity to encode directionality in the three-dimensional space. The most efficient strategy is the addition of carbon nucleophiles to α–imino esters, since it can simultaneously construct a carbon skeleton and a quaternary carbon center,[4] and syntheses providing α,α–dialkyl and α,α–alkyl-aryl substituted α–amino acid derivatives have been developed.[5]. It was reported that rhodium[6] and palladium[7] can catalyze the addition of arylboronic acids to five-membered cyclic N-sulfonyl ketimines substituted with an ester group to give α,α–diaryl α–amino acid derivatives. Isoindolinone cores are a common motif to a variety of compounds with potent biological activities. Melting points were determined using an Electro-thermal 9100 apparatus in open capillaries and are uncorrected Compound names are those generated by ChemBioDraw Ultra 12.0 following IUPAC conventions. Substrates, 3-aryl 3-hydroxyisoindolinones, were synthesized in high yields from readily available starting materials, by employing addition of a Grignard or organolithium reagent to phthalimide or 5,6-dichlorophthalimide.[20]

General Procedure
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