In general, it was found that the 3,5-difluorophenylsulfonyl hydrazides exhibited the optimum reactivity for secondary cyclic radicals, but in many cases, such as primary derived radicals, the simple tosyl-substituted hydrazide can be employed . However, in the case of arylation, simple tosyl hydrazides performed well . As a general matter, the byproducts resulting from hydrazide immolation are easily removed (N2 gas and a sulfinate salt) upon aqueous workup. These reactions are ideal for parallel screening workflows as they can be conducted on very small scale. As discussed below they can also be scaled up with ease due to their homogeneity. Explorations thus far have revealed the majority of 2°-cyclic sulfonyl hydrazides to be bench stable substances, particularly in the case of tosyl hydrazides. 2°-acyclic and 1°-tosyl hydrazides obtained after hydrazone reduction should be used shortly after preparation whereas 1° hydrazides prepared through Mitsunobu (different NSO2Ar regioisomer, Table , box) are more stable (several days on a benchtop). A user guide based on current data is provided in the Supplementary Materials.