Reactivity of N‐1‐(2,2‐dichloroalkylidene) amides

A general synthetic route to N‐1‐(2,2‐dichloroalkylidene) amides is described, starting from aliphatic 2,2‐dichloroaldehydes and an appropriate N‐unsubstituted amide. The adducts thus formed were converted into N‐(1,2,2‐trichloroalkyl) amides with thionylchloride and subsequently dehydrohalogenated with triethylamine. These N‐acyl α,α‐dichloroaldimines were found to be very apt to nucleophilic addition at the activated carbon‐nitrogen double bond, producing stable adducts. The configuration of the adducts in solution was determined by NMR‐spectroscopy. Treatment of the title compounds with lithium aluminium hydride in diethylether afforded 1,2‐dialkylaziridines. The reactivity of these N‐acyl α,α‐dichloroaldimines was compared with the reactivity of the N‐alkyl analogues and the corresponding oxygen analogues, i.e. α,α‐dihalogenated aldehydes.