Multifunctional asymmetric catalysis

Two types of general and practical enantioselective catalysts, namely; bimetallic completes and Lewis acid-Lewis base bifunctional catalysts Here developed based on the concept of multifunctional catalysis. In the first part of this review, the first example of a catalytic enatioselective nitro-Mannich reaction as well as a direct catalytic enantioselective aldol reaction of 2-hydroxyacetophenone using bimetallic complexes is discussed, The new complex, composed of ytterbium, potassium, and BINOL in a ratio of 1 : 1 :3, promoted the nitro-Mannich reaction of nitromethane with up to 91% ee. On the other hand, second generation ALE catalyzed an enantioselectivity e and diastereoselective nitro-Mannich reaction of nitroalkanes in up to 83% ee with a diastereomeric ratio up to 7:1, Moreover, the reaction of aldehydes with 2-hydroxyacetophenone in the presence of LLB, KHMDS, and H2O selectively gave the corresponding anti-alpha,beta -dihydroxy; ketones in up to 95% ee and, in the presence of the catalyst prepared from linked-BINOL and 2 eq of Et2Zn, selectively afforded the syn-alpha,beta -dihydroxy ketones in up to 86% ee, In the second part, the development of new catalysts displaying a Lewis acidity and a Lewis basicity is described. The Lewis acid of the catalyst activates aldehydes, imines, acyl quinoliniums, and ketones, At the same time, the Lewis base activates the nucleophile (TMSCN). Catalysts of this type produced a highly enantioselective cyanation of these electrophiles, Application of the catalytic enantioselective cyanosilylation of aldehydes to a total synthesis of epothilones is also described.