Development of an axially chiral sp3P/sp3NH/sp2N-combined linear tridentate ligand—fac-selective formation of Ru(II) complexes and application to ketone hydrogenation. Issue 26 (30th June 2016)

• Record Type: Journal Article
• Authors: Yamamura, Tomoya; Nakane, Satoshi; Nomura, Yuko; Tanaka, Shinji; Kitamura, Masato
• Is Part Of: Tetrahedron. Volume 72:Issue 26(2016)
• Page Start: 3781
• Page End: 3789
• Publication Date: 2016-06-30
• Subjects: Chiral ligand -- Tridentate -- fac-Ru complex -- Catalysis -- Hydrogenation; Chemistry, Organic -- Periodicals; 547.005
• DOI: 10.1016/j.tet.2016.02.007
• Languages: English
• ISSNs: 0040-4020

Abstract

Abstract: A newly developed chiral linear tridentate ligand, R-PN(H)N (R=H or Ph), possesses Ph2 P and PyCH2 NH groups at C(2) and C(2′) positions of the 1, 1′-binaphthyl skeleton without or with a C(3)-Ph substituent. The steric effect of C(3)-Ph and the electronic effect of the DMSO co-ligand realize the facial selective generation of fac -RuCl2 (Ph-PN(H)N)(dmso) and fac -[Ru(H-PN(H)N)(dmso)3 ](BF4 )2, respectively. Both an H–Ru⋯sp 3 N–H reaction site responsible for the donor–acceptor bifunctional catalyst (DACat) and a fence/plane chiral context were constructed by means of the following advantageous points: i) the sp 3 P, sp 3 N, and sp 2 N ligating atoms have different electronic properties; ii) DMSO trans to sp 3 N strongly coordinates to Ru and is fixed by a PyC(6)H⋯OS hydrogen bond; and iii) the single NH function simplifies the DACat reaction site. The synergistic effect has led to success in the asymmetric hydrogenation of sterically demanding ketones. Structural characteristics of first-row transition metal complexes of R-PN(H)N have been also investigated. Graphical abstract: