Derivatives of optically active 1-chloro-2,2-bismethoxycarbonylaziridine: absolute configuration and X-ray molecular structure of (–)-(E)-1-chloro-2-methoxycarbonyl-2-methylcarbamoylaziridine

X-Ray analysis of (–)-(E)-1-chloro-2-methoxycarbonyl-2-methylcarbamoylaziridine shows that the absolute configuration at the chiral centres is (–)-(1R,2R); this enables us to assign the S configuration to the chiral nitrogen atom in the related compound (+)-1-chloro-2,2-bismethoxycarbonylaziridine.