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Synthesis 2018; 50(10): 1965-1972
DOI: 10.1055/s-0036-1591767
paper
© Georg Thieme Verlag Stuttgart · New York

One-Pot Synthesis of Isoquinuclidines via 2,6-Diaryl-1,2-dihydropyridines using (E,E)-Cinnamylideneacetophenones as Templates

Authors


Thanks are due to the University of Aveiro and FCT/MCT for the financial support of the project PT-DZ/0005, the QOPNA research Unit (FCT UID/QUI/00062/2013), and CICECO–Aveiro Institute of Materials (POCI-01-0145-FEDER-007679 – FCT UID /CTM/50011/2013) through national founds and, where applicable, co-financed by the FEDER, within the PT2020 Partnership Agreement, and to the Portuguese NMR Network. E. M. P. Silva acknowledges funding from FEDER – Operational Competitiveness and Internationalization Programme (COMPETE 2020) through project NORTE-01-0145-FEDER-000011. D. H. A. Rocha is thankful for the research grant BI/UI51/4889/2016 of the project PT-DZ/0005.
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Publication History

Received: 31 December 2017

Accepted after revision: 29 January 2018

Publication Date:
07 March 2018 (online)

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Graphical Abstract

‡ Both authors contributed equally to this work.

Abstract

Diastereoselective Diels–Alder reactions of 2,6-diaryl-1,2-dihydropyridines with N-methylmaleimide afford highly substituted isoquinuclidines in good chemical yield (30–50%). This sequential one-pot synthesis is performed under microwave irradiation and involves, primarily, the synthesis of 2,6-diaryl-1,2-dihydropyridines by a 6π-azaelectrocyclisation involving an intermediate α,β,γ,δ-di-unsaturated imine, obtained by condensation of (E,E)-cinnamylideneacetophenones with amines. This procedure easily converts unstable 2,6-diaryl-1,2-dihydropyridines into, otherwise inaccessible, isoquinuclidines without any kind of manipulation.

Key words

nitrogen heterocycles - Schiff bases - electrocyclic reactions - microwave chemistry - Diels–Alder reaction

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