During the optimization of the nucleophilic coupling fragment, it was postulated that the addition of base or modification of the acyl group on the oxime may have a beneficial effect (Scheme 7B). When pyridine was added to the reaction mixture, the desired reaction was inhibited, while the formation of other side products still persisted (entry 2). The addition of triethylamine greatly suppressed the undesired reactivity, but only 9% yield of 4-1 was observed (entry 3). Subjecting acetylated oxime (6-15) to the standard conditions prevented side product formation, but only trace product was obtained (entry 4); however, the addition of triethylamine increased the yield of 4-1 to 13% (entry 5). Alteration of the oxime coupling partner to the pivalate (6-14) resulted in a modest increase in the yield (18%, entry 6). Finally, when the oxime benzoate (3-7) was utilized in the Liebeskind pyridine synthesis, the desired product (4-1) was obtained in 38% yield (entry Scheme 7. Optimization of Fragment Coupling Partners for the Liebeskind Pyridine Synthesis a Yield of the crude reaction mixture on 0.1 mmol scale, was determined by 1 H NMR using 1,3,5-trimethoxybenzene as an internal standard. b 16 h. To maximize synthetic convergence, we turned our attention to reinvestigating the challenging pyridine synthesis between the stannyl dienoate (3-6) and the oxime benzoate (3-7). After extensive interrogation of reaction conditions (Scheme 8), we determined that the use of stoichiometric Cu(OAc)2 coupled with quinuclidine as an amine additive resulted in a substantially greater yield of pyridine 3-1 (52%, entry 1). Decreasing the amount of Cu(OAc)2 had a deleterious effect on the product yield (entries 2-3). Additionally, a variety of common copper salts such as CuTC, Cu(OTf)2, etc., were examined in this reaction, which only produced minimal 3-1 (entries 4-5). Employing other transition metals (e.g., Pd or Ni) were not effective in accessing 3-1. Replacing quinuclidine with various trialkylamines, including Bn3N, Et3N, NMM or DABCO, greatly decreased the yields (entries 6-9). Aside from amine additives, phosphines, fluoride sources, and other bases were also parameters that were screened, but these approaches all resulted in diminished yields of 3-1 (not shown). Modification of solvents to, e.g., N-methylformanilide, EtOAc, PhMe/MeCN, or adjustment of concentration also led to eroded yields of the pyridine product (entries 10-15).