With N-H aziridine 1, no product formed, even with our optimized conditions of 10 mol% Sc(OTf) 3 groups were well tolerated. Interestingly, when acetate was used as an activating N-substitutent, no 1'-amino-tetrahydrofuran product formed; instead, dihydrooxazole 13 was the sole product. This type of rearrangement has been noted previously. Overall, a variety of electrophilic N-substituents allow for productive cyclization, and the aziridine must be activated to engage.