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Readily available 1,2-amino alcohols provide the framework for a new generation of chiral carboxylic acid catalysts that rival the acidity of the widely used chiral phosphoric acid catalyst (S)-TRIP. Covalently… Click to show full abstract
Readily available 1,2-amino alcohols provide the framework for a new generation of chiral carboxylic acid catalysts that rival the acidity of the widely used chiral phosphoric acid catalyst (S)-TRIP. Covalently linked thiourea sites stabilize the carboxylate conjugate bases of these catalysts via anion-binding, an interaction that is largely responsible for the low pKa values. The utility of the new catalysts is illustrated in the context of challenging [4+2] cycloadditions of salicylaldehyde-derived acetals with homoallylic and bishomoallylic alcohols, providing polycyclic chromanes in highly enantioselective fashion.
Journal Title: Journal of the American Chemical Society
Year Published: 2020
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