Molecules, Vol. 26, Pages 1165: New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2 ′-Bis(aminomethyl)-1,1′-Binaphthyl

Molecules, Vol. 26, Pages 1165: New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2′-Bis(aminomethyl)-1,1′-Binaphthyl
Molecules doi: 10.3390/molecules26041165
Authors:
Yasuhiro Sato
Yuichi Kawata
Shungo Yasui
Yoshihito Kayaki
Takao Ikariya

As a candidate for bifunctional asymmetric catalysts containing a half-sandwich C–N chelating Ir(III) framework (azairidacycle), a dinuclear Ir complex with an axially chiral linkage is newly designed. An expedient synthesis of chiral 2,2′-bis(aminomethyl)-1,1′-binaphthyl (1) from 1,1-bi-2-naphthol (BINOL) was accomplished by a three-step process involving nickel-catalyzed cyanation and subsequent reduction with Raney-Ni and KBH4. The reaction of (S)-1 with an equimolar amount of [IrCl2Cp*]2 (Cp* = h5–C5(CH3)5) in the presence of sodium acetate in acetonitrile at 80 °C gave a diastereomeric mixture of new dinuclear dichloridodiiridium complexes (5) through the double C–H bond cleavage, as confirmed by 1H NMR spectroscopy. A loss of the central chirality on the Ir centers of 5 was demonstrated by treatment with KOC(CH3)3 to generate the corresponding 16e amidoiridium complex 6. The following hydrogen transfer from 2-propanol to 6 provided diastereomers of hydrido(amine)iridium retaining the bis(azairidacycle) architecture. The dinuclear chlorido(amine)iridium 5 can serve as a catalyst precursor for the asymmetric transfer hydrogenation of acetophenone with a substrate to a...

Source: Molecules - February 22, 2021 Category: Chemistry Authors: Yasuhiro Sato Yuichi Kawata Shungo Yasui Yoshihito Kayaki Takao Ikariya Tags: Article Source Type: research