New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2′-Bis(aminomethyl)-1,1′-Binaphthyl
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 (<b>1</b>) from...
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MDPI AG
2021-02-01
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| Series: | Molecules |
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| Online Access: | https://www.mdpi.com/1420-3049/26/4/1165 |
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doaj-a8c1c7d4ff54452383f780a4bde7a0762021-02-23T00:04:41ZengMDPI AGMolecules1420-30492021-02-01261165116510.3390/molecules26041165New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2′-Bis(aminomethyl)-1,1′-BinaphthylYasuhiro Sato0Yuichi Kawata1Shungo Yasui2Yoshihito Kayaki3Takao Ikariya4Department of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, JapanDepartment of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, JapanDepartment of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, JapanDepartment of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, JapanDepartment of Chemical Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, 2-12-1-E4-1 O-okayama, Meguro-ku, Tokyo 152-8552, JapanAs 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 (<b>1</b>) 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 KBH<sub>4</sub>. The reaction of (<i>S</i>)-<b>1</b> with an equimolar amount of [IrCl<sub>2</sub>Cp*]<sub>2</sub> (Cp* = h<sup>5</sup>–C<sub>5</sub>(CH<sub>3</sub>)<sub>5</sub>) in the presence of sodium acetate in acetonitrile at 80 °C gave a diastereomeric mixture of new dinuclear dichloridodiiridium complexes (<b>5</b>) through the double C–H bond cleavage, as confirmed by <sup>1</sup>H NMR spectroscopy. A loss of the central chirality on the Ir centers of <b>5</b> was demonstrated by treatment with KOC(CH<sub>3</sub>)<sub>3</sub> to generate the corresponding 16e amidoiridium complex <b>6</b>. The following hydrogen transfer from 2-propanol to <b>6</b> provided diastereomers of hydrido(amine)iridium retaining the bis(azairidacycle) architecture. The dinuclear chlorido(amine)iridium <b>5</b> can serve as a catalyst precursor for the asymmetric transfer hydrogenation of acetophenone with a substrate to a catalyst ratio of 200 in the presence of KOC(CH<sub>3</sub>)<sub>3</sub> in 2-propanol, leading to (<i>S</i>)-1-phenylethanol with up to an enantiomeric excess (ee) of 67%.https://www.mdpi.com/1420-3049/26/4/1165bifunctional catalystmetal-ligand cooperationdinuclear complexiridacyclecyclometalationasymmetric transfer hydrogenation |
| collection |
DOAJ |
| language |
English |
| format |
Article |
| sources |
DOAJ |
| author |
Yasuhiro Sato Yuichi Kawata Shungo Yasui Yoshihito Kayaki Takao Ikariya |
| spellingShingle |
Yasuhiro Sato Yuichi Kawata Shungo Yasui Yoshihito Kayaki Takao Ikariya New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2′-Bis(aminomethyl)-1,1′-Binaphthyl Molecules bifunctional catalyst metal-ligand cooperation dinuclear complex iridacycle cyclometalation asymmetric transfer hydrogenation |
| author_facet |
Yasuhiro Sato Yuichi Kawata Shungo Yasui Yoshihito Kayaki Takao Ikariya |
| author_sort |
Yasuhiro Sato |
| title |
New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2′-Bis(aminomethyl)-1,1′-Binaphthyl |
| title_short |
New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2′-Bis(aminomethyl)-1,1′-Binaphthyl |
| title_full |
New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2′-Bis(aminomethyl)-1,1′-Binaphthyl |
| title_fullStr |
New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2′-Bis(aminomethyl)-1,1′-Binaphthyl |
| title_full_unstemmed |
New Bifunctional Bis(azairidacycle) with Axial Chirality via Double Cyclometalation of 2,2′-Bis(aminomethyl)-1,1′-Binaphthyl |
| title_sort |
new bifunctional bis(azairidacycle) with axial chirality via double cyclometalation of 2,2′-bis(aminomethyl)-1,1′-binaphthyl |
| publisher |
MDPI AG |
| series |
Molecules |
| issn |
1420-3049 |
| publishDate |
2021-02-01 |
| description |
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 (<b>1</b>) 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 KBH<sub>4</sub>. The reaction of (<i>S</i>)-<b>1</b> with an equimolar amount of [IrCl<sub>2</sub>Cp*]<sub>2</sub> (Cp* = h<sup>5</sup>–C<sub>5</sub>(CH<sub>3</sub>)<sub>5</sub>) in the presence of sodium acetate in acetonitrile at 80 °C gave a diastereomeric mixture of new dinuclear dichloridodiiridium complexes (<b>5</b>) through the double C–H bond cleavage, as confirmed by <sup>1</sup>H NMR spectroscopy. A loss of the central chirality on the Ir centers of <b>5</b> was demonstrated by treatment with KOC(CH<sub>3</sub>)<sub>3</sub> to generate the corresponding 16e amidoiridium complex <b>6</b>. The following hydrogen transfer from 2-propanol to <b>6</b> provided diastereomers of hydrido(amine)iridium retaining the bis(azairidacycle) architecture. The dinuclear chlorido(amine)iridium <b>5</b> can serve as a catalyst precursor for the asymmetric transfer hydrogenation of acetophenone with a substrate to a catalyst ratio of 200 in the presence of KOC(CH<sub>3</sub>)<sub>3</sub> in 2-propanol, leading to (<i>S</i>)-1-phenylethanol with up to an enantiomeric excess (ee) of 67%. |
| topic |
bifunctional catalyst metal-ligand cooperation dinuclear complex iridacycle cyclometalation asymmetric transfer hydrogenation |
| url |
https://www.mdpi.com/1420-3049/26/4/1165 |
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