To begin, sodium 5-chloropyrazine-2-thiolate (N1a) and 5-fluoro-4-iodopyridin-2-amine (E1a) were selected from AbbVie's building block library to probe the robustness of Miyake's reported conditions. Heterocyclic sulfide N1a and halogen E1a were selected as we considered these challenging substrates that contain nucleophilic and electrophilic functionality capable of cross and self-coupling photochemically or thermally (SNAr). 2a,7 These coupling partners were also selected based on the ubiquity of nitrogen containing heterocycles in small-molecule drugs and their propensity to complicate TM catalyzed cross-coupling reactions. Evaluating conditions similar to those reported by Miyake and co-workers (Table , Entry 1) resulted in completely consumed N1a with desired product (P1) (15%) formed as a complex mixture with several by-products (23%) and unreacted E1a (62%). Compound P2 was identified as the most prevalent by-product (5%), likely formed from over-reaction of P1 with N1a. The remaining by-products (18%) are suspected to be oligomers derived from N1a based on its consumption relative to E1a and the formation of P2. Evaluating alternative solvents led to the identification of MeCN, which improved conversion to P1 (26%) but also increased the formation of P2 (10%) (Table , Entry 2). To probe if by-product formation was caused by SNAr side reactions, the reaction was repeated in the absence of light resulting in trace reaction (Table , Entry 3). Given N1a's complete consumption, we posited that evaluating soluble organic bases with thiophenol N1b might taper the thiolate's reactivity in turn reducing by-product formation.