A Powerful Chiral Counteranion Motif for Asymmetric Catalysis

Abstract

Room to swing a cat: A chiral disulfonimide has been designed as a powerful new motif for asymmetric catalysis. As a first illustration, a highly efficient and enantioselective Mukaiyama aldol reaction has been developed (see scheme). The actual catalyst is proposed to be an N-silyl imide which is generated in situ

Stronger Brønsted Acids: Recent Progress

“…183 They developed an alternative oxychlorination of 173 by treatment with Nchlorosuccinimide (NCS) (Scheme 63). Although NCS is more expensive than O 2 , this reaction protocol is very useful because the reaction proceeds under mild conditions.…”

Practical Synthetic Approach to Chiral Sulfonimides (CSIs) – Chiral Brønsted Acids for Organocatalysis

“…Giernoth reported the synthesis of parent compound 1a (X, Y = H), [1] whereas List demonstrated elegantly that in situ generated silylated sulfonimine 1c (Y = SiMe 3 , via 1b) is a highly efficient Lewis acid organocatalyst for Mukaiyama aldol reactions. [2] In recent years, the rapid development of organocatalysis has complemented the traditional organometallic and enzymatic approaches to asymmetric catalysis in the construction of chiral molecules and scaffolds. [3] With organocatalysis, synthetic chemists can construct chiral molecules in a highly efficient and stereoselective manner under rather mild conditions.…”

2.07 The Aldol Reaction: Organocatalysis Approach

“…The actual catalyst is proposed to be an in situ generated N-silyl imide. 203 An excellent contribution was made by Rawal and coworkers in 2003 who developed a chiral Brønsted acid catalyst, TADDOL (α,α,α′,α′-tetraaryl-2,2-dimethyl-1,3-dioxolane-4,5-dimethanol) in hetero-Diels-Alder reactions. 204 They also developed that a simple chiral diol of the TADDOL 361 catalyzes Mukaiyama aldol reactions between aldehydes and silyl enol ethers of amides 374.…”