Formal Deoxygenative Hydrogenation of Lactams Using PNHP-Pincer Ruthenium Complexes under Nonacidic Conditions

Osamu Ogata; Hideki Nara; Kazuhiko Matsumura; Yoshihito Kayaki

doi:10.1021/acs.orglett.9b03878

Formal Deoxygenative Hydrogenation of Lactams Using PN^HP-Pincer Ruthenium Complexes under Nonacidic Conditions

Org Lett. 2019 Dec 20;21(24):9954-9959. doi: 10.1021/acs.orglett.9b03878. Epub 2019 Dec 6.

Authors

Osamu Ogata¹, Hideki Nara¹, Kazuhiko Matsumura¹, Yoshihito Kayaki²

Affiliations

¹ Corporate Research and Development Division , Takasago International Corporation , 1-4-11 Nishi-Yawata , Hiratsuka , Kanagawa 254-0073 , Japan.
² 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: 31809060
DOI: 10.1021/acs.orglett.9b03878

Abstract

A formal deoxygenative hydrogenation of amides to amines with RuCl₂(NHC)(PN^HP) (NHC = 1,3-dimethylimizadol-2-ylidene, PN^HP = bis(2-diphenylphosphinoethyl)amine) is described. Various secondary amides, especially NH-lactams, are reduced with H₂ (3.0-5.0 MPa) to amines at a temperature range of 120-150 °C with 1.0-2.0 mol % of PN^HP-Ru catalysts in the presence of Cs₂CO₃. This process consists of (1) deaminative hydrogenation of secondary amides to generate primary amines and alcohols, (2) dehydrogenative coupling of the transient amines with alcohols to generate imines, and (3) hydrogenation of imines to give the formally deoxygenated secondary amine products.