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Preparation of a Series of Supported Nonsymmetrical PNP‐Pincer Ligands and the Application in Ester Hydrogenation
Author(s) -
Konrath Robert,
Spannenberg Anke,
Kamer Paul C. J.
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201903379
Subject(s) - pincer movement , catalysis , combinatorial chemistry , ligand (biochemistry) , ruthenium , chemistry , pincer ligand , organic chemistry , receptor , biochemistry
In contrast to their symmetrical analogues, nonsymmetrical PNP‐type ligand motifs have been less investigated despite the modular pincer structure. However, the introduction of mixed phosphorus donor moieties provides access to a larger variety of PNP ligands. Herein, a facile solid‐phase synthesis approach towards a diverse PNP‐pincer ligand library of 14 members is reported. Contrary to often challenging workup procedures in solution‐phase, only simple workup steps are required. The corresponding supported ruthenium‐PNP catalysts are screened in ester hydrogenation. Usually, industrially applied heterogeneous catalysts require harsh conditions in this reaction (250–350 °C at 100–200 bar) often leading to reduced selectivities. Heterogenized reusable Ru‐PNP catalysts are capable of reducing esters and lactones selectively under mild conditions.