Conjugate addition of hydroxylamino derivatives to alkylidene malonates in the presence of chiral Lewis acids

Recent Advances in Metal-Catalyzed Asymmetric 1,4-Conjugate Addition (ACA) of Nonorganometallic Nucleophiles

“…The asymmetric aza-Michael reaction is one of the most significant methods for constructing valuable chiral nitrogen-containing molecules. , In recent decades, diverse chiral metal-complex catalysts − have been applied to this reaction (Scheme ). For instance, impressive achievements have been made by the Hii and Sodeoka groups using palladium-phosphine complexes ( L121 –Pd) as the catalysts. − The usefulness of this method was further demonstrated in the synthesis of the optically active molecule torcetrapib, providing the important intermediates with high enantiomeric purity in excellent yield. , The mechanisms of these reactions were also systematically investigated by X-ray crystallography, mass spectrometry, NMR, and UV–vis spectroscopy, as well as kinetic studies .…”

C2-Symmetric Chiral Bis(Oxazoline) Ligands in Asymmetric Catalysis

“…The aza-Michael reaction of N , O -bis(trimethylsilyl)hydroxylamine with arylidene malonates 153 is catalyzed by several box-based catalysts and some of them give enantioselectivities up to 76% ee. However, catalyst [( S )- 1 / Cu(OTf) 2 ] is not among them, and both yield and enantioselectivity afforded by this complex are unsatisfactory …”

Synthesis of Ethyl 5‐Hydroxyisoxazolidine‐4‐carboxylates via Michael Addition/Intramolecular Hemiketalisation

“…[5] Herein, we describe the highly stereocontrolled synthesis of ethyl 5-hydroxyisoxazolidine-4-carboxylate through a Lewis acid induced Michael addition of hydroxylamine derivatives to alkylideneacetoacetates, followed by intramolecular hemiketal formation. The use of acetoacetates in this field is rather unusual and has the advantage of introducing a reactive keto functionality that may be further elaborated.…”