Bifunctional Squaramide‐Catalysed Asymmetric Michael/Hemiketalization/Retro‐Aldol Reaction of Unsaturated Thiazolones with α‐Nitroketones: Synthesis of Chiral 4‐Acyloxythiazole Derivatives

An efficient and practical organocatalytic asymmetric cascade Michael/hemiketalization/retro‐aldol reaction of unsaturated thiazolones with α‐nitroketones by using cyclohexanediamine‐derived bifunctional squaramide as the catalyst has been developed. Under mild conditions, a broad range of chiral 4‐acyloxythiazole derivatives were obtained in high yields (up to 98% yield) with excellent enantioselectivities (up to 95% ee). Meanwhile, a few synthetic transformations have been demonstrated. magnified image