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.
Department of Chemistry, Imperial College London, Exhibition Road, South Kensington, London SW7 2AZ, UK. mike.hill@imperial.ac.uk
Michael S
MS
Hill
Peter B
PB
Hitchcock
Stephen M
SM
Mansell
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