We found that this complex is able to oxidize cyclic and acyclic [beta]-hydroxy ketones in very high enantioselectivity and in satisfactory yield (Fig.
5, resulted in 3-hydroxylated products in high enantioselectivity (Fig.
Only in one case, with substrate 9, a certain enantioselectivity was achieved (26% ee, Table 2, No.
However, moderate enantioselectivity was achieved only in one case with the catalytic Cu(II) system and with stoichiometric Ti-system.
High enantioselectivity can also be achieved through the use of chiral borane catalysts to effect aldols starting with acyclic ketones.
Ghosez employed keteneiminium and nitrosocarbamyl reagents prepared from chiral amides to effect 2 + 2 and 2 + 4 cycloadditions with high enantioselectivity.
Diversa's biocatalyst technology has a huge potential in improving performance characteristics such as enantioselectivity
, activity, stability and expression.
In addition, Phage Display further expedites the process of selecting enzymes with optimal substrate specificity and enantioselectivity
by allowing for simultaneous testing of multiple enzyme variations.
PeptiCLEC-BL's excellent enantioselectivity
in coupling both natural and unnatural amino acids and racemic amines, makes the catalyst extremely useful for the synthesis of optically pure pharmaceuticals.
Enzymes exhibit a number of characteristics that make them very appealing catalysts, including: a high degree of specificity yielding a product of greater purity; striking selectivity, including enantioselectivity
which also contributes to product purity; activity under mild temperatures and pressures, which limits the need for expensive containment and control equipment; activity in easy-to-handle solvents, which reduces the hazards and costs of waste disposal; a lack of toxicity in contrast to traditional chemical catalysts.