In search of diamine analogs of the α,α-diphenyl prolinol privileged chiral organocatalyst. Synthesis of diamine derivatives of α,α-diphenyl-(S)-prolinol and their application as organocatalysts in the asymmetric Michael and Mannich reactions

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• 作者：Gloria Reyes-Rangel ; Jorge Vargas-Caporali ; Eusebio Juaristi ; ^{juaristi@relaq.mx" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Organocatalysis ; Proline derivatives ; Thorpe&ndash ; Ingold effect ; Asymmetric Michael addition ; Asymmetric Mannich reaction ; Water effect
• 刊名：Tetrahedron
• 出版年：2016
• 出版时间：21 January 2016
• 年：2016
• 卷：72
• 期：3
• 页码：379-391
• 全文大小：1783 K

文摘

This paper describes improved reaction conditions for the substitution of the hydroxyl group in (S)-diphenyl(pyrrolidin-2-yl)methanol by the azide group, which was then reduced to the diamine derivative. We examined two protecting groups (N-Bn and N-Boc) on the pyrrolidine nitrogen in order to functionalize the primary amino group into various amide, alkylated amine, sulfonamide, thiourea and triazole derivatives. Notably, carefully controlled conditions were required to generate the desired derivatives from the sterically hindered benzhydrylamine moiety. Unexpectedly, upon removal of the N-protecting group in derivatives containing electrophilic polar double bonds (CS, CO) cyclization took place, affording products such as amidines. The target compounds were evaluated as bifunctional organocatalysts in the asymmetric Michael and Mannich addition reactions. (S)-2-(Azidodiphenylmethyl)pyrrolidine (S)-7 was identified as the most efficient organocatalyst among the various diamine derivatives of α,α-diphenyl-(S)-prolinol prepared in this work.