Along with ynamides, we further investigated the reactions of general alkynes. Based on our electrochemical studies of alkynes, we expect that diphenylacetylene (E1/2 ox = +1.85 V vs SCE) should be compatible with this hydroamination reaction. Indeed, the reaction of diphenylacetylene produced the desired alkenylpyrazole 4 in 60% yield (eq. 1). Because of the high redox potential, acetylene, 1-phenyl-1propyne, and 4-octyne are not reactive. Furthermore, a gram-scale reaction of ynesulfonamide 2f with pyrazole produced the expected enamide product in 72% isolated yield demonstrating the synthetic practicability of this transformation. In addition to the aforementioned electrochemical studies, control experiments and Stern-Volmer fluorescence quenching studies were performed to gain further mechanistic insight into this photoredox catalyzed hydroamination reaction of ynamides with nitrogen heteroaromatic nucleophiles. When the radical scavenger 2,2,6,6-tetramethylpiperidin-1-oxyl (TEMPO) or butylated hydroxytoluene (BHT) was subjected to the reaction of 1a and pyrazole under the standard condition, the hydroamination reaction was substantially suppressed, suggesting the involvement of radical intermediates (Scheme 3a). Stern-Volmer fluorescence quenching studies (Scheme 3b) of the ynesulfonamide 1a and pyrazole systems showed that the irradiated photocatalyst was quenched by 1a (Ksv = 75.08) rather than pyrazole (Ksv = 25.31). Taken together the cyclic voltammetry measurements of ynamide 1a (E1/2 ox = +1.44 V vs SCE) and pyrazole (E1/2 ox = +2.21 V vs SCE), it is feasible that the generation of ynamide cation radical I from photocatalyzed single-electron oxidation of ynesulfonamide 1a may initial this photoinduced transformation.