Chiral phospholene and phospholane chalcogenides: stereochemistry and chiral recognition by multinuclear NMR spectroscopy of their Rh2[(R)-MTPA]4 adducts.

Full NMR spectral assignments of the phospholene chalcogenides 1–12 are presented and their stereochemistry proven. The enantiomeric ratio of any of these compounds can be monitored easily by adding one mole equivalent of the chiral auxiliary Rh2[(R)-MTPA]4 (MTPA-H ≡ Mosher's acid) and subsequent NMR inspection. Some surprisingly large diastereomeric signal dispersion is observed in the 1H NMR spectra of the adducts, leading to the conclusion that intramolecular anisotropy interaction between groups inside the ligand molecules exists. The dependence of dispersion effects on the nature of the chalcogenide atom is investigated. Chirality 15:391–399, 2003. © 2003 Wiley-Liss, Inc.