Synthesis 2023; 55(11): 1714-1723
DOI: 10.1055/s-0042-1751383
paper
Special Issue dedicated to Prof. Cristina Nevado, recipient of the 2021 Dr. Margaret Faul Women in Chemistry Award

Synthesis of 1H-Isochromenes and 1,2-Dihydroisoquinolines by Indium(III)-Catalyzed Cycloisomerization of ortho-(Alkynyl)benzyl Derivatives

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Financial support was provided by the Ministerio de Ciencia, Innovación y Universidades (PGC2018-097792-B-I00 and PID2021-122335NB-I00), the Consellería de Cultura, Educación e Ordenación Universitaria, Xunta de Galicia (GRC2018/039 and GRC2022/039) and the European Regional Development Fund (EDRF).


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This article is dedicated to Prof. Cristina Nevado in celebration of the Dr. Margaret Faul Women in Chemistry Award.

Abstract

1H-Isochromenes and 1,2-dihydroisoquinolines are synthesized by regioselective indium(III)-catalyzed intramolecular hydrofunctionalization of o-(alkynyl)benzyl derivatives. The reaction with o-(alkynyl)benzyl alcohols and amines proceeds using indium triiodide (5–10 mol%) in toluene at 80–100 °C via regioselective 6-endo-dig intramolecular alkyne hydroalkoxylation or hydroamination in good yields. Alternatively, the cycloisomerization reaction of o-(alkynyl)benzaldehydes and imine derivatives using InI3 (5 mol%) and the Hantzsch ester (120 mol%) takes place, under milder reaction conditions, to give a variety of functionalized 1H-isochromenes and 1,2-dihydroisoquinolines through a domino cycloisomerization/reduction approach.

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Publikationsverlauf

Eingereicht: 14. August 2022

Angenommen: 21. September 2022

Artikel online veröffentlicht:
17. November 2022

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