Chiral amide from (1S, 2R)-(+)-norephedrine and furoic acid: An efficient catalyst for asymmetric Reformatsky reaction

Abstract

Chiral amide derived from (1S, 2R)-(+)-norephedrine and 2-furoic acid was found to catalyse the asymmetric Reformatsky reaction between prochiral aldehydes and α-bromo ethylacetate with diethylzinc as zinc source. The corresponding chiral β-hydroxy esters were formed in 99% yield with over 80% enantiomeric excess. The presence of air was found to be essential for the effective CC bond formation. The mechanism for the catalytic reaction was proposed.

Chiral Ammonium Aryloxides as Brønsted Base Catalysts for the Henry Reaction of Nitroalkanes to Aromatic and Aliphatic Aldehydes

“…in 1992 using a lanthanum‐based catalyst, a lot of work has been directed towards the development of efficient catalytic systems. As far as organometallic catalysts are concerned, copper in combination with chiral nitrogen ditopic ligands have been mainly reported in the literature . From an organocatalysis point of view, despite some pioneer achievements reported as early as 1994, the first efficient approach emanated from the group of Nagasawa in 2005 by using a chiral bifunctional thiourea‐combined guanidinium salt as liquid‐liquid phase transfer catalyst (PTC) allowing to obtain high enantioselectivity of up to 92 % ee .…”

Recent developments in the asymmetric Reformatsky-type reaction

“…The zinc-mediated Reformatsky reaction of aldehydes with ethyl bromoacetate ( 9b ) was investigated by Velmathi and Ananthi in the presence of a chiral amide ligand derived from (+)-norephedrine and 2-furoic acid [ 44 ]. Indeed, using 30 mol % of chiral amide ligand 51 in THF at room temperature, the reaction of a range of aldehydes 48a,d,e,h,i,l – q with ethyl bromoacetate ( 9b ) led to the corresponding chiral β-amino alcohols 50a,d,e,h,i,l – q in moderate to excellent yields (35–95%) and enantioselectivities (30–90% ee), as shown in Scheme 20 .…”

“… Reformatsky reaction of aldehydes with ethyl bromoacetate in the presence of a chiral amide ligand [ 44 ]. …”

Preparation of a novel magnetically recoverable copper complex catalyst and its application in the Henry reaction

“…The research and development of copper‐ligating materials with enhanced catalytic activities has important practical significance for ligand synthesis, the simulation of metal enzymes, and operation costs . As common catalysts for the asymmetric Henry reaction, copper‐containing complex catalysts are stable and economical and exhibit relatively high catalytic activities …”