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Resolution of the first non-racemic diquats

Published in Chemistry. 2010, vol. 16, no. 9, p. 2797-2805
Abstract Three tricyclic diquats with an eight-membered ring were prepared and shown to be the first configurationally stable derivatives of their kind. Resolution was achieved by using chiral hexacoordinated phosphorus BINPHAT and TRISPHAT anions. The diquat cations were obtained in high diastereo- and enantiomeric purity (ee>96 % in most cases). X-ray diffraction analysis coupled with circular dichroism (CD) measurements allowed a precise determination of the relative and absolute configuration of the salts. The barriers to racemization of these compounds were calculated by using CD time-course measurements at different temperatures, affording Delta G? values above 25 kcal mol-1. Derivatives 4 a, 4 b, and 4 c are the first eight-membered-ring derivatives with only three ring constraints to be resolved. This manuscript also reports the first procedure to remove TRISPHAT anions after diastereomeric separation.
Keywords ChiralityConfiguration determinationDiquatsRacemization barriersResolution
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VACHON, Jérôme, BERNARDINELLI, Gérald Hugues, LACOUR, Jérôme. Resolution of the first non-racemic diquats. In: Chemistry, 2010, vol. 16, n° 9, p. 2797-2805. doi: 10.1002/chem.200902562 https://archive-ouverte.unige.ch/unige:5260

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Deposited on : 2010-02-23

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