Asymmetric oxohydroxylation of α-alkyl enoates with potassium permanganate catalyzed by monocationic quaternary...
Organocatalysts are one of the bravest attempts to mimic enzyme catalysis that Mother Nature uses. Enantioselective organocatalysts are small organic molecules that can catalyze reactions in the absence of metals or metal ions. Cinchona Alkaloids are chiral organic compounds that can be used as chiral catalyst in many reactions such as aldol condensation, Mannich reaction, Henry reaction or Michael addition.
Enantioselective Organocatalysis has developed rapidly in recent years. Among the catalysts developed for this purpose, Cinchona Alkaloid derivatives have risen to prominence, and have been used to catalyze a wide range of reactions.
Easy-to-use reaction conditions, operational simplicity, environmentally friendly reagents devoid of potentially toxic metal ions, and readily available tunable organocatalysts operating via different substrate activation modes brought organocatalysis to the forefront of asymmetric synthesis. Nowadays, organocatalysis is considered to be the third pillar of asymmetric catalysis along with metal catalysis and biocatalysis; it is increasingly used in the pharmaceutical and agrochemical industries.
Cinchona alkaloid-derived organocatalysts are widely employed in various asymmetric transformations, yielding products with high enantiopurity under mild conditions and with often a low catalyst loading.
An outstanding class of Cinchona alkaloid derived organocatalysts exhibits a bifunctional mode of activation by the incorporation of an acidic unit, such as urea, thiourea, squaramide or sulfonamide moieties, giving rise to the simultaneous activation of both the nucleophile and the electrophile.
Lots of examples can be reviewed in the Buchler Chiral Catalyst Search data base.