Optimized Scalable Synthesis of Chiral Iridium Pyridyl‐Phosphinite (Pyridophos) Catalysts
Abstract Iridium catalysts with chiral P,N ligands have greatly enhanced the scope of asymmetric olefin hydrogenation because they do not require a coordinating group near the C=C bond like Rh and Ru catalysts. Pyridophos ligands, possessing a conformationally restricted annulated pyridine framework...
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crwiley:10.1002/hlca.202000181 2024-06-02T07:58:21+00:00 Optimized Scalable Synthesis of Chiral Iridium Pyridyl‐Phosphinite (Pyridophos) Catalysts Müller, Marc‐André Ganić, Adnan Hörmann, Esther Kaiser, Stefan Maywald, Matthias Roseblade, Stephen J. Schrems, Marcus G. Schumacher, Andreas Woodmansee, David Pfaltz, Andreas Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung 2020 http://dx.doi.org/10.1002/hlca.202000181 https://onlinelibrary.wiley.com/doi/pdf/10.1002/hlca.202000181 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/hlca.202000181 en eng Wiley http://onlinelibrary.wiley.com/termsAndConditions#vor Helvetica Chimica Acta volume 103, issue 12 ISSN 0018-019X 1522-2675 journal-article 2020 crwiley https://doi.org/10.1002/hlca.202000181 2024-05-03T11:20:10Z Abstract Iridium catalysts with chiral P,N ligands have greatly enhanced the scope of asymmetric olefin hydrogenation because they do not require a coordinating group near the C=C bond like Rh and Ru catalysts. Pyridophos ligands, possessing a conformationally restricted annulated pyridine framework linked to a phosphinite group, proved to be particularly effective, inducing high enantioselectivities in the hydrogenation of a remarkably broad range of substrates. Here we report the development of an efficient scalable synthesis for the two most versatile Ir‐pyridophos catalysts, derived from 2‐phenyl‐8‐hydroxy‐5,6,7,8‐tetrahydroquinoline or the analogue with a five‐membered carbocyclic ring, respectively, by modification and optimization of the original synthetic route. The optimized route renders both catalysts readily accessible in multi‐gram quantities in analytically pure form in overall yields of 26–37 %, starting from acetophenone and cyclopentanone or cyclohexanone, respectively. A major advantage of the new synthesis is the efficient and practical kinetic resolution of the late‐stage pyridyl alcohol intermediates with commercial immobilized Candida antarctica lipase B, giving access to both enantiomers of these catalysts as essentially enantiopure compounds. The catalysts are obtained as crystalline solids, which are air‐stable and can be stored for years at −20 °C without notable decomposition. Article in Journal/Newspaper Antarc* Antarctica Wiley Online Library Helvetica Chimica Acta 103 12 |
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Wiley Online Library |
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English |
description |
Abstract Iridium catalysts with chiral P,N ligands have greatly enhanced the scope of asymmetric olefin hydrogenation because they do not require a coordinating group near the C=C bond like Rh and Ru catalysts. Pyridophos ligands, possessing a conformationally restricted annulated pyridine framework linked to a phosphinite group, proved to be particularly effective, inducing high enantioselectivities in the hydrogenation of a remarkably broad range of substrates. Here we report the development of an efficient scalable synthesis for the two most versatile Ir‐pyridophos catalysts, derived from 2‐phenyl‐8‐hydroxy‐5,6,7,8‐tetrahydroquinoline or the analogue with a five‐membered carbocyclic ring, respectively, by modification and optimization of the original synthetic route. The optimized route renders both catalysts readily accessible in multi‐gram quantities in analytically pure form in overall yields of 26–37 %, starting from acetophenone and cyclopentanone or cyclohexanone, respectively. A major advantage of the new synthesis is the efficient and practical kinetic resolution of the late‐stage pyridyl alcohol intermediates with commercial immobilized Candida antarctica lipase B, giving access to both enantiomers of these catalysts as essentially enantiopure compounds. The catalysts are obtained as crystalline solids, which are air‐stable and can be stored for years at −20 °C without notable decomposition. |
author2 |
Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung |
format |
Article in Journal/Newspaper |
author |
Müller, Marc‐André Ganić, Adnan Hörmann, Esther Kaiser, Stefan Maywald, Matthias Roseblade, Stephen J. Schrems, Marcus G. Schumacher, Andreas Woodmansee, David Pfaltz, Andreas |
spellingShingle |
Müller, Marc‐André Ganić, Adnan Hörmann, Esther Kaiser, Stefan Maywald, Matthias Roseblade, Stephen J. Schrems, Marcus G. Schumacher, Andreas Woodmansee, David Pfaltz, Andreas Optimized Scalable Synthesis of Chiral Iridium Pyridyl‐Phosphinite (Pyridophos) Catalysts |
author_facet |
Müller, Marc‐André Ganić, Adnan Hörmann, Esther Kaiser, Stefan Maywald, Matthias Roseblade, Stephen J. Schrems, Marcus G. Schumacher, Andreas Woodmansee, David Pfaltz, Andreas |
author_sort |
Müller, Marc‐André |
title |
Optimized Scalable Synthesis of Chiral Iridium Pyridyl‐Phosphinite (Pyridophos) Catalysts |
title_short |
Optimized Scalable Synthesis of Chiral Iridium Pyridyl‐Phosphinite (Pyridophos) Catalysts |
title_full |
Optimized Scalable Synthesis of Chiral Iridium Pyridyl‐Phosphinite (Pyridophos) Catalysts |
title_fullStr |
Optimized Scalable Synthesis of Chiral Iridium Pyridyl‐Phosphinite (Pyridophos) Catalysts |
title_full_unstemmed |
Optimized Scalable Synthesis of Chiral Iridium Pyridyl‐Phosphinite (Pyridophos) Catalysts |
title_sort |
optimized scalable synthesis of chiral iridium pyridyl‐phosphinite (pyridophos) catalysts |
publisher |
Wiley |
publishDate |
2020 |
url |
http://dx.doi.org/10.1002/hlca.202000181 https://onlinelibrary.wiley.com/doi/pdf/10.1002/hlca.202000181 https://onlinelibrary.wiley.com/doi/full-xml/10.1002/hlca.202000181 |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
Helvetica Chimica Acta volume 103, issue 12 ISSN 0018-019X 1522-2675 |
op_rights |
http://onlinelibrary.wiley.com/termsAndConditions#vor |
op_doi |
https://doi.org/10.1002/hlca.202000181 |
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Helvetica Chimica Acta |
container_volume |
103 |
container_issue |
12 |
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1800741665947779072 |