Synthesis, complexation chemistry and a case of self-recognition of chiral phosphite ligands

Reaction of (R)-(-)-1-phenyl-2,2,3-trimethylbutane-1,3-diol with PCl3 affords trans-(S)-2-chloro-4,4,5,5-tetramethyl-6-(R)-phenyl-1,3,2-dioxaphosphorinane, which couples smoothly with catechol, resorcinol, 2,2-dimethyl-1,3-propanediol and fluorenedimethanol to form the corresponding diphosphites. By three different methods (oxidation to phosphates, electrospray mass spectrometry with deuterium labelled samples, and NMR spectroscopic analysis of borane adducts) it was shown that on use of racemic materials a degree, less than absolute, of self-recognition is involved in the formation of the diphosphite obtained with catechol. No self-recognition is involved in the assembly of the product with resorcinol. Determination of the degree of self-recognition was made difficult by the identity of the NMR spectra of the meso and racemic forms of the diphosphites obtained from catechol. (C) 1999 Elsevier Science Ltd. All rights reserved.