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2‐(2‐Oxoalkylidene)‐1,3‐oxazolidine derivatives were synthesized in good to excellent yields regiospecifically through the catalyst‐free electrophilic ring expansion of N‐unprotected aziridines and the ketene C=O double bond of α‐oxoketenes, in situ generated from the microwave‐assisted Wolff rearrangement of 2‐diazo‐1,3‐diketones. The ring expansion predominantly underwent an SN1 process and the hydrogen bond decides the (E)‐configuration of products. [ABSTRACT FROM AUTHOR]

An efficient method for the direct synthesis of aziridine‐containing chiral tridentate ligands was developed from enantiopure aziridines and salicylaldehydes. The method achieved the regiospecific cleavage of more substituted C−N bonds of aziridines through an iminium‐mediated self‐ring opening reaction of aziridines with up to 95% yield and complete inversion of configuration. The (S)‐2‐alkylaziridine‐derived tridentate ligands displayed excellent activity and stereoselectivity in the zinc trifluoromethanesulfonate‐catalyzed asymmetric aldol reactions of acetone and aromatic aldehydes. [ABSTRACT FROM AUTHOR]