Using a supramolecular asymmetric ion pairing strategy, an enantioselective [1,2]-Stevens is feasible on substrates devoid of stereogenic quaternary nitrogen atoms.

Hexacoordinated phosphorus BINPHAT anion 1 is an efficient NMR chiral solvating agent for quaternary ammonium cations (quats) derived from Tröger base leading to large separations of the proton signals of the enantiomers and even in polar solvent media such as CD(3)CN (Delta Delta delta up to 0.12 ppm). Quite surprisingly, this efficacy in the NMR split efficiency is not translated into a supramolecular stereocontrol (Pfeiffer effect) of the cation configuration by the anion.

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Enantioselective [1,2]-Stevens Rearrangement of Quaternary Ammonium Salts. A Mechanistic Evaluation. -The paper describes the strict enantioselective [1,2]-Stevens rearrangement of quaternary ammonium ions, using enantiopure anionic counterions as asymmetric auxiliaries. The methodology involves double transmission of chirality: (i) a supramolecular transfer of the helical chirality of the anion in (I) to the axial chirality of the cation in (I) followed by (ii) its very effective translation (90-100%) during the Stevens rearrangement to the centered chirality of amines (II). -(GONCALVES-FARBOS, M.-H.; VIAL, L.; LACOUR*, J.; Chem. Commun. (Cambridge) 2008, 7, 829-831; Dep. Org. Chem., Univ. Geneva, CH-1211 Geneva 4, Switz.; Eng.) -M. Paetzel 25-123