Synthesis 2017; 49(07): 1613-1622
DOI: 10.1055/s-0036-1588107
paper
© Georg Thieme Verlag Stuttgart · New York

Towards a Series of Chiral Primary Amines Bearing α-Amino Acid and Benzo[d]imidazole Pendants, and Their Application in Asymmetric Aldol Reactions

Pravinkumar Hansraj Mohite
Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 53210, Czech Republic   eMail: filip.bures@upce.cz
,
Pavel Drabina
Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 53210, Czech Republic   eMail: filip.bures@upce.cz
,
Filip Bureš*
Institute of Organic Chemistry and Technology, Faculty of Chemical Technology, University of Pardubice, Studentská 573, Pardubice 53210, Czech Republic   eMail: filip.bures@upce.cz
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Publikationsverlauf

Received: 03. Oktober 2016

Accepted after revision: 02. November 2016

Publikationsdatum:
08. Dezember 2016 (online)


Abstract

A straightforward reaction path towards chiral primary amines bearing α-amino acid and benzo[d]imidazole pendants has been developed. Six starting essential α-amino acids were converted into the target chiral amines in a four-step synthesis. The prepared amines were screened as organocatalysts in the direct asymmetric aldol reaction between 4-nitrobenzaldehyde or isatin and acetone or cyclohexanone. The aldol adducts were obtained in good chemical yields, diastereoselectivity­ up to 97:3 (reactions with cyclohexanone), and enantioselectivity up to 71% ee. Trifluoroacetic acid and benzoic acid proved to be the best cocatalysts for the aldol process on 4-nitrobenzaldehyde and isatin, respectively.

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