On the Asymmetric Induction in Proline-Catalyzed Aldol Reactions: Reagent-Controlled Addition Reactions of 2,2-Dimethyl-1,3-dioxane-5-one to Acyclic Chiral α-Branched Aldehydes
作者:Jasna Marjanovic Trajkovic、Vesna Milanovic、Zorana Ferjancic、Radomir N. Saicic
DOI:10.1002/ejoc.201701073
日期:2017.11.9
Proline-catalyzed aldol addition reactions of 2,2-dimethyl-1,3-dioxane-5-one to chiral aldehydes proceed under reagent stereocontrol (in both matched and mismatched cases) if aldehyde α-oxy or α-amino substituents are acyclic. For cyclic substituents, the stereochemical outcome of the aldolization in mismatched cases is difficult to predict.
Stereodivergent construction of three contiguous stereocenters in catalytic doubly diastereoselective nitroaldol reactions of a-chiral aldehydes with nitroacetaldehyde dimethyl acetal using two types of heterobimetallic catalysts is described. A La-Li-BINOL (LLB) catalyst afforded anti,syn-nitroaldol products in >20:1-14:1 selectivity, and a Pd/La/Schiff base catalyst afforded complimentary syn,syn-nitroaldol products in 10:1-5:1 selectivity.