Cleavage of N-H Bond of Ammonia via Metal-Ligand Cooperation Enables Rational Design of a Conceptually New Noyori-Ikariya Catalyst

Pavel A Dub; Asuka Matsunami; Shigeki Kuwata; Yoshihito Kayaki

doi:10.1021/jacs.8b12961

Cleavage of N-H Bond of Ammonia via Metal-Ligand Cooperation Enables Rational Design of a Conceptually New Noyori-Ikariya Catalyst

J Am Chem Soc. 2019 Feb 13;141(6):2661-2677. doi: 10.1021/jacs.8b12961. Epub 2019 Feb 4.

Authors

Pavel A Dub¹, Asuka Matsunami¹, Shigeki Kuwata¹, Yoshihito Kayaki¹

Affiliation

¹ Department 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 , Japan.

PMID: 30715874
DOI: 10.1021/jacs.8b12961

Abstract

The asymmetric transfer hydrogenation (ATH) of ketones/imines with Noyori-Ikariya catalyst represents an important reaction in both academia and fine chemical industry. The method allows for the preparation of chiral secondary alcohols/amines with very good to excellent optical purities. Remarkably, the same chiral Noyori-Ikariya complex is also a precatalyst for a wide range of other chemo- and stereoselective reductive and oxidative transformations. Among them are enantioselective sulfonamidation of acrylates (intramolecular aza-Michael reaction) and carboxylation of indoles with CO₂. Development of these catalytic reactions has been inspired by the realized cleavage of the N-H bond of sulfonamides and indoles by the 16e^- amido derivative of the 18e^- precatalyst via metal-ligand cooperation (MLC). This paper summarizes our efforts to investigate N-H bond cleavage of gaseous ammonia in solution via MLC and reports the serendipitous discovery of a new class of chiral tridentate κ³[ N, N', N″] Ru and Ir metallacycles, derivatives of the famous M-FsDPEN catalysts (M = Ru, Ir). The protonation of these metallacycles by strong acids containing weakly coordinating (chiral) anions generates ionic complexes, which were identified as conceptually novel Noyori-Ikariya precatalysts. For example, the ATH of aromatic ketones with some of these complexes proceeds with up to 99% ee.