The similar reactivity was also reflected in the comparable yield in the reaction of PMP OSF (1) and PMP(Cbz)ASF ( ) with morpholine amino-oxetane (86%) vs amino-azetidine (106, 84%). Despite the small kinetic differences between PMP(Cbz)ASF 11 and PMP OSF 1, the larger activation energy of PMP(Cbz)ASF 11, coupled with an also larger Arrhenius pre-exponential factor, results in a situation where the rate of deFS of PMP(Cbz)ASF 11 is higher at higher temperatures and the rate of deFS of PMP OSF 1 is higher at lower temperatures (Scheme 4c). At 43 °C, the rates of deFS of both species appear equal (kOSF = kASF). PMP(Cbz)ASF 11 was reacted with a diverse range of primary and secondary amines as well as anilines, providing amino-azetidines (Scheme 5). Like with OSFs, the functional group tolerance was broad, and sensitive functionalities such as free alcohols, tertiary amines, esters, and pyridines were well tolerated, as well as complex late-stage examples, providing azetidine functionalized fluoxetine (121) and amlodipine (122). NH-Azoles, sulfoximines 41 and phosphorous-based nucleophiles were also successful (123-129) providing a series of novel motifs. Azetidine sulfonyl fluorides were amenable to SuFEx reactivity using alkoxides, shown here with cholesterol and demonstrating the potential for conjugation with complex molecules (130).