Chiral Lewis Acid

Chiral Lewis acids (CLAs) are a special class of Lewis acid catalyst used in enantioselective/asymmetric synthesis reactions which produceoptically active products from optically inactive or impure starting materials. This type of preferential formation of one enantiomer or diastereomerover the other is formally an asymmetric induction. The electron accepting atom of CLAs are typically metal halides such as those of indium,zinc, lithium, aluminium, titanium, or boron and the chiral ligands employed for synthesizing CLAs most often are structurally chiral, cyclic diolssuch as a bisphenol or binapthol derivative. While achiral lewis acids promote the synthesis of racemic mixtures in a myriad of different reactions for quite some time, over the last three decades, CLAs have been used to promote the enantioselective production of optically pure products in Diels-Alder reactions, the ene reaction [2+2] cycloaddition reactions, hydrocyanation of aldehydes, and most notably, Sharpless expoxidations.

Klappentext

Chiral Lewis acids (CLAs) are a special class of Lewis acid catalyst used in enantioselective/asymmetric synthesis reactions which produceoptically active products from optically inactive or impure starting materials. This type of preferential formation of one enantiomer or diastereomerover the other is formally an asymmetric induction. The electron accepting atom of CLAs are typically metal halides - such as those of indium,zinc, lithium, aluminium, titanium, or boron - and the chiral ligands employed for synthesizing CLAs most often are structurally chiral, cyclic diolssuch as a bisphenol or binapthol derivative. While achiral lewis acids promote the synthesis of racemic mixtures in a myriad of different reactions for quite some time, over the last three decades, CLAs have been used to promote the enantioselective production of optically pure products in Diels-Alder reactions, the ene reaction [2+2] cycloaddition reactions, hydrocyanation of aldehydes, and most notably, Sharpless expoxidations.