Synthesis of 2-Oxazolines from Ring Opening Isomerization of 3-Amido-2-Phenyl Azetidines

Abstract

Chiral 2-oxazolines are valuable building blocks and famous ligands for asymmetric catalysis. The most common synthesis involves the reaction of an amino alcohol with a carboxylic acid. In this paper, an efficient synthesis of 2-oxazolines has been achieved via the stereospecific isomerization of 3-amido-2-phenyl azetidines. The reactions were studied in the presence of both Brønsted and Lewis acids, and Cu(OTf)2 was found to be the most effective.

Gold-Catalyzed Nucleophilic Ring-Opening Reaction of 2-Alkynylazetidines with Alcohols

“…Four-membered N -heterocycle azetidines are useful building blocks in organic synthesis, and the ring strain of azetidines can be utilized to promote various transformations . Among them, ring-opening of azetidines is one of the most useful methodologies for the synthesis of functionalized nitrogen-containing compounds. − In the case of Lewis acid catalyzed ring opening of azetidines with nucleophiles, the nitrogen atom in azetidine is activated electrophilically to cause the nucleophilic ring opening (Scheme A) …”