108791-92-0Relevant articles and documents
Further Studies of the Kinetic Template Effect in the Metal Ion-catalysed Reactions of ortho-Donor-substituted Aryl Halides with Tertiary Phosphines. Structural Requirements of the Template
Allen, David W.,Cropper, Paul E.,Smithurst, Peter G.,Ashton, Peter R.,Taylor, Brian F.
, p. 1989 - 1994 (2007/10/02)
The reactions of a series of Schiff's bases, derived from ortho-chloro-, bromo- or iodo-benzaldehydes and p-anisidine, with tertiary phosphines in the presence of nickel(II) bromide in refluxing ethanol proceed with displacement of the ortho-halogen to form the related ortho-substituted arylphosphonium salts.These reactions appear to be examples of a kinetic template effect in which the Schiff's base moiety aids the catalytic role of the metal ion in promoting the substitution reaction.Introduction of a second donor atom into the substituent group present at the nitrogen of related Schiff's bases inhibits the reactions due to diversion of the metal ion in other modes of coordination.The reactions are also inhibited by steric crowding at the imino-nitrogen.A range of other aryl halides bearing ortho-substituents having the potential to act as co-ordination templates has been prepared and their reactions with phosphines in the presence of metal ions studied enabling the rather critical nature of effective template groups to be defined.Detailed 13C n.m.r. data are also reported for the Schiff's bases and related arylphosphonium salts.
