Synthesis and characterization of bisoxazolines- and pybox-copper(ii) complexes and their application in the coupling of α-carbonyls with functionalized amines

Abstract

Binuclear complexes [{(DMOX)CuCl}2(μ-Cl)2] (1), mononuclear complexes [(DMOX)CuBr2] (2) (DMOX = 4,5-dihydro-2-(4,5-dihydro-4,4-dimethyloxazol-2-yl)-4,4-dimethyloxazole) and the pybox Cu(II) complex [(Dm-Pybox)CuBr2] (3) (Dm-Pybox = 2,6-bis[4',4'-dimethyloxazolin-2'-yl]pyridine) were obtained by reactions of CuX2 (X = Cl, Br) with DMOX and Dm-Pybox ligands, respectively. The molecular structures of 1, 2 and 3 have been determined by single-crystal X-ray diffraction analyses. The complexes 2 and 3 are efficient in catalyzing α-amination of ketones and esters through α-bromo carbonyl intermediate. The procedures are environmentally benign methods using molecular oxygen as an oxidant with water as the only byproduct.

Recent advances in the synthesis of α-amino ketones

“…In 2014, Huang and co-workers showed that the use of a non-commercial dimethyl-Pybox ligand with MacMillan's conditions marginally increased the yields for comparable substrates. 42 And in 2017, Truong and Nguyen reported a novel copper-based metal-organic framework that functioned as an Scheme 1 Importance of α-amino ketones in synthetic and medicinal chemistry.…”

Umkehr der Polarität: α‐Aminierungen von Carbonylverbindungen mit Stickstoffnukleophilen

“…Bemerkenswerterweise wurde diese Umwandlung auf die Synthese des biologisch relevanten β‐Lactamgerüstes angewendet. Im gleichen Jahr beschrieb die Gruppe von Huang eine Kupfer‐katalysierte aerobe Aminierung von Ketonen unter Verwendung von cyclischen sekundären Aminen . Die Reaktion wird durch die Verwendung von pybox und anderen Bisoxazolin‐Liganden möglich, wodurch Arylketone mit guten bis hervorragenden Ausbeuten in die entsprechenden α‐Aminoketone umgewandelt werden.…”

Two cadmium(II) complexes with oxazoline-based ligands as effective catalysts for C–N cross-coupling reactions

“…Within the past years, reports about pincer and bisoxazolines transition metal complexes' exceptional catalytic abilities have been reported [2][3][4][5][6][7][8]. Continuing our research interests in bisoxazolines and pincer complexes due to their rich chemistry [9][10][11], we seek to discover new transition metal complexes and hope to exploit their chemistry in a variety of potential catalytic applications.…”