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Synthesis of Phosphanylferrocenecarboxamides Bearing Guanidinium Substituents and Their Application in the Palladium‐Catalyzed Cross‐Coupling of Boronic Acids with Acyl Chlorides
Author(s) -
Charvátová Hana,
Císařová Ivana,
Štěpnička Petr
Publication year - 2017
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201600461
Subject(s) - chemistry , palladium , catalysis , ligand (biochemistry) , ferrocene , medicinal chemistry , chloride , coupling reaction , aqueous solution , organic chemistry , receptor , biochemistry , electrode , electrochemistry
Phosphanylferrocene donors bearing polar guanidinium substituents, namely acylguanidinium chloride, [Ph 2 PfcCONHC(NH 2 )NH 2 ]Cl ( 1 ), and amidoguanidinium chloride, [Ph 2 PfcCONHCH 2 CH 2 NHC(NH 2 )NH 2 ]Cl ( 2 ; fc = ferrocene‐1,1′‐diyl), have been prepared and characterized. As functional phosphane donors, they were employed in the synthesis of Pd II complexes bearing 2‐[(dimethylamino)methyl‐κ N ]phenyl‐κ C 1 (L NC ) and η 3 ‐allyl supporting ligands, [(L NC )PdCl(L‐κ P )] and [(η 3 ‐C 3 H 5 )PdCl(L‐κ P )] (L = 1 and 2 ), respectively. These defined complexes as well as their surrogates generated in situ from the respective palladium(II) precursor and the phosphanylferrocene ligand were evaluated as catalysts for the coupling of boronic acids with acyl chlorides to give ketones in an aqueous biphasic system. The coupling reaction proceeded best with a simple catalyst formed from Pd(OAc) 2 and ligand 2 , which (at 0.2 mol‐% Pd loading) produced substituted benzophenones from benzoyl chlorides and benzeneboronic acids in very good yields. These yields could then be further improved by a proper choice of the reaction partners. Analogous reactions involving aliphatic substrates generally afforded lower yields.