Decarboxylative Mannich Reactions with N‐Alkyl Imines
作者:Marine Pinaud、Leïla Vaïtilingom、Gayathiri Gnanalingam、Tania Xavier、Erwan Le Gall、Marc Presset
DOI:10.1002/ejoc.202300198
日期:2023.5.8
DecarboxylativeMannichreactions with substituted malonic acids half oxyesters as pronucleophiles has been applied to N-alkyl imines. Key to success was the use of an organocatalyst in combination with acid additives to favor the desired pathway. These conditions were also found to be compatible with the in situ generation of the imine, leading to an original multicomponent reaction.
The reaction of [Pt2Me4(mu-SMe2)(2)] (1) with the imine 3-(CF3)C6H4CH=NCH2Ph (2a) yields the cyclometallated compound [PtMe3-(CF3)C6H3CH=NCH2Ph}(SMe2)] (3a) by selective metallation at the less hindered of the two ortho positions of the aryl ring followed by loss of methane. A similar reaction for imine 2-(CF3)C6H4CH=NCH2Ph (2c) yieIds the cyclometallated compound [PtMe2-(CF3)C6H3CH=NCH2Ph} (SMe2)] (3c). The reactions of these compounds with triphenylphosphine in (1 : 1) ratio produce compounds [PtMe3-(CF3)C6H3CH=NCH2Ph}(PPh3)] (4a) and [PtMe2-(CF3)C6H3CH=NCH2Ph}(PPh3)] (4c). The X-ray structure of 4a is reported. An excess of triphenylphosphine produces metallacycle cleavage and [PtMe3-(CF3)C6H3CH=NCH2Ph} (PPh3)(2)] (5a) is formed with the imine acting as a [C-] unidentate ligand. Oxidative addition of methyl iodide to compounds 4a and 4c gives cyclometallated platinum(IV) complexes. Imines 3,5-(CF3)(2)C6H3CH=NCH2Ph (2b) and 2-F-6-(CF3)C6H3CH=NCH2Ph (2d) fail to react with [Pt2Me4(mu-SMe2)(2)] (1). (C) 1998 Elsevier Science Ltd. All rights reserved.