yields (up to 99 %) and excellent diastereo- (up to >99:1 dr) and enantioselectivities (up to 95 % ee) using a low catalyst loading. Most importantly, these results show that the concept of DNA-basedasymmetriccatalysis can be expanded to new synthetic transformations offering an efficient, sustainable, and highly selective tool for the construction of chiral building blocks.
Catalytic Conjugate Additions of Carbonyl Anions under Neutral Aqueous Conditions
作者:Michael C. Myers、Ashwin R. Bharadwaj、Benjamin C. Milgram、Karl A. Scheidt
DOI:10.1021/ja0520161
日期:2005.10.1
The conjugateaddition of carbonylanions catalyzed by thiazolium salts that is fully operative under neutral aqueous conditions has been accomplished. The combination of alpha-keto carboxylates and thiazolium-derived zwitterions produces reactive carbonylanions in a buffered protic environment that readily undergo conjugateadditions to substituted alpha,beta-unsaturated 2-acyl imidazoles. The scope
Diastereoselective Trapping of Transient Carboxylic Oxonium Ylides with α,β‐Unsaturated 2‐Acyl Imidazoles
作者:Mengchu Zhang、Tianyuan Zhang、Dan Zhang、Wenhao Hu
DOI:10.1002/adsc.202000701
日期:2020.11.4
By developing a diastereoselective reaction of cyclopropene carboxylic acids with α,β‐unsaturated 2‐acylimidazoles, we reported here a Michael‐type trapping of transient carboxylic oxonium ylides. This transformation provides a direct approach for the construction of valuable γ‐butenolide derivatives in good yields (60–99%) with high diastereoselectivities (up to >95:5 dr) under mild reaction conditions
Mirror mirror on the wall: By taking advantage of the unique structural features of L‐DNA, the first examples of left‐helical enantioselective induction in the field of DNA‐based asymmetriccatalysis were realized. Most importantly, this approach is the only one that allows a reliable and predictable access to both enantiomers for any given reaction.
We report here the first example of an RNA-based catalyst involving a catalytically active metal complex interacting in a non-covalent fashion with short RNA sequences.