Interestingly, a small amount of 3e was noted, which increased from 1-2 h, then decreased from 2-4 h, at which time the cheletropic extrusion product 5e was observed. The 2 h reaction aliquot was further analyzed by 1D TOCSY (see Figure S-9 in the Supporting Information), which revealed a unique spin system corresponding to 3e. These data are the first experimental evidence supporting the conclusion that the reaction is under thermodynamic control (vide supra), where the [3,9]-aziridine 3e gives rise to 5e. This result is further supported by the computational data, linear alkyl chains, including a primary alkyl chloride, furnished 4f and 12f-14f as the sole products in moderate yields and high dr of >20:1. Isopropyl-substituted aziridine 14 was tolerated to furnish 14f, albeit in moderate yield, indicating the sensitivity of the reaction to steric effects. Small amounts of cheletropic extrusion product (~8%) were also observed in reactions of branched aziridines. Enantiopure benzyl-substituted aziridine (S,R)-15, obtained in 94% ee, was subjected to the reaction conditions; the product 15f was obtained in 39% yield and an excellent >20:1 dr.