Racemic N-aryl bis(amidines) and bis(amidinates): on the trail of enantioselective organolanthanide catalysts.
A series of racemic N-aryl-substituted trans-1,2-diaminocyclohexyl (t-1,2-DACH)-linked bis(amidines) were synthesised and their solution behaviour, and solid-state structures were investigated. The amidine functionalities within these compounds were extremely sterically hindered, with ortho-aryl substitution found to hinder N-Ar bond rotation. The results of these studies were used to rationalise the lack of reactivity of these compounds with [Y{N(SiMe(3))(2)}(3)]. Dilithiation of the t-1,2-DACH linked bis(amidines) did, however, proceed easily and the solution behaviour and solid-state structures of the resulting THF-solvated lithium amidinates were investigated. All the compounds showed similar structures in the solid-state, while NMR experiments indicated that the solid-state structures were likely to be maintained in solution. Attempted metathesis reactions with YCl(3) did not, however, yield the desired yttrium chloride complexes.
Hill
Michael S
MS
Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, UK. mike.hill@imperial.ac.uk
Hitchcock
Peter B
PB
Mansell
Stephen M
SM
D000578:Amidines / Q000138:chemical synthesis / Q000737:chemistry*; D002384:Catalysis; D018360:Crystallography, X-Ray; D003514:Cyclohexylamines / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D013237:Stereoisomerism; D015019:Yttrium / Q000737:chemistry*
D000578:Amidines; D003514:Cyclohexylamines; D009942:Organometallic Compounds; D015019:Yttrium; C030435:1,2-cyclohexanediamine