Aza-Darzens Route

Aziridines Bearing Electron-withdrawing Croups Esters and Amides 1.3.1.1 Aza-Darzens Route... 

Three groups of polar processes to form aziridines are shown in Scheme 16. In every case, each of the two reactants must be capable of acting formally as either a bis-nucleophile or a bis-electrophile, or they must each have both nucleophilic and electrophilic character. In the aza-Darzens route (B-83MI 101-01, 84CHEC-(7)47), the imine acts as an electrophile at carbon and later as a nucleophile at nitrogen, while the a-haloenolate acts initially as a nucleophile at carbon and later as an electrophile at the same carbon. The roles of the two components are reversed for the polar aziridination route, which is related to the epoxidation reaction. In the last route, the 1,2-dihalide or a-haloenone acts formally as a bis-electrophile while the amine acts as a bis-nucleophile. 

The aza-Darzens route to aziridines (B-83MI 101-01, 84CHEC-i(7)47> is analogous to the Darzens reaction of a-haloenolates with carbonyl compounds to produce oxiranes. It continues to be the most popular of the three pathways shown in Scheme 52 as judged by the diversity of examples reported. Selected examples which illustrate primarily the variation of the electron-withdrawing group are shown below. 

---