Optically active cyclopalladated derivatives of arylimines. Crystal structures of (+)-[{Pd[p-MeOC6H3CHNCH2-(1S,2R,5S)CHCH2CH2CHC(Me)2CHCH2](µ-X)}2] (X = Cl or Br), (+)-[Pd{p-MeOC6H3CHNCH2-(1S,2R,5S)-CHCH2CH2CHC(Me)2CHCH2}Cl(PPh3)] and (+)-[{Pd[p-MeOC6H3CHNCH2-(1S,2R,5S)-CHCH2CH2CHC(Me)2CHCH2]Cl}2{Fe(δ5-C5H4PPh2

Abstract

4-Methoxybenzaldehyde reacted with (–)-(1S,2R,5S)-2-aminomethyl-6,6-dimethylbicyclo[3.1.1]heptane in

benzene to give the new chiral arylimine p-MeOC₆H₄CHNCH₂-(1S,2R,5S)-CHCH₂CH₂CHC(CH₃)₂CHCH₂ [(–)-I]. Cyclopalladation of the imine with Pd(O₂CMe)₂ in MeCO₂H, followed by treatment with LiCl, LiBr or KI, gave the corresponding di-µ-halide-bridged organometallics (+)-[{Pd[p-MeOC₆H₃CHNCH₂-(1S,2R,5S)-CHCH₂CH₂CHC(Me)₂CHCH₂](µ-X)}₂] [X = Cl (+)-1a, Br (+)-1b or I (+)-1c]. Subsequent treatment of these compounds with triphenylphosphine, pyridine (py) or 1,1′-bis(diphenylphosphino)ferrocene (dppf) in acetone yielded the corresponding cyclopalladated derivatives (+)-[Pd{p-MeOC₆H₃CHNCH₂-(1S,2R,5S)-CHCH₂CH₂CHC(Me)₂CHCH₂}X(PPh₃)] [X = Cl (+)-2a, Br (+)-2b or I (+)-2c], (+)-[Pd{p-MeOC₆H₃CHNCH₂-(1S,2R,5S)-CHCH₂CH₂CHC(CH₃)₂CHCH₂}X(py)] [X = Cl (+)-3a, Br (+)-3b or I (+)-3c] and (+)-[{Pd[p-MeOC₆H₃CHNCH₂-(1S,2R,5S)-CHCH₂CH₂CHC(Me)₂CHCH₂)]X}₂(dppf)] [X = Cl (+)-4a, Br (+)-4b or I (+)-4c], which have been characterized by NMR and mass spectrometry, optical rotation and elemental analysis. The crystal structures of (+)-1a, (+)-1b, (+)-2a and (+)-4b·CH₂Cl₂ have been determined.