Direct Arylation of Thiazoles on Water

Phosphine‐Free, Palladium‐Catalyzed Arylation of Heterocycles through CH Bond Activation with Pivalic Acid as a Cocatalyst

“…Among the solvents investigated, DMF was clearly the best choice (Table 1 entries 1-4). After screening a variety of bases (i.e., K 2 CO 3 , Ag 2 O, tBuOK, Cs 2 CO 3 , and K 3 PO 4 ), K 3 PO 4 was found to be the most effective (Table 1 entries [4][5][6][7][8][9]. Remarkably, by using a carboxylic acid as the additive enabled efficient CÀH bond functionalization of caffeine.…”

“…Direct C À H arylation of heterocycles has been achieved by using Rh, [1a, 2] Cu, [3] and more extensively, Pd-based catalysis. [4] Despite impressive progress in this area, these methodologies still suffer from several notable deficiencies. First, the majority of these reactions require more reactive, but generally less available and significantly more expensive aryl iodides, and only scattered examples of the use of aryl bromides have emerged.…”

“…Third, unavailability, high expense, air or moisture sensitivity, and/ or specificity of the ligands (mainly electron-rich, bulky phosphines), are often encountered in the reactions. [1,2,4] More importantly, most methods are applied to only a few types of heterocycles, thus limiting the scope of the methodologies. [1,3,4] From an industrial and economic standpoint, a ligand-free process would provide much-needed impetus for the development of improved catalyst systems.…”

“…[1,2,4] More importantly, most methods are applied to only a few types of heterocycles, thus limiting the scope of the methodologies. [1,3,4] From an industrial and economic standpoint, a ligand-free process would provide much-needed impetus for the development of improved catalyst systems. In recent years, phosphine-free, palladium-catalyzed CÀH bond arylation of azoles and related heteroarenes have been reported.…”

Synthesis of functionalized thiophene/phenyl co-oligomers by direct arylation of thiophenes

“…Therefore, we also tested conditions published by Greaney et al who reported about the successful use of [Pd(dppf)Cl 2 ], PPh 3 , and Ag 2 CO 3 in the arylation of thiazoles. 45 Adopting this strategy for our synthetic purpose, we were able to synthesize several thiophenylphenylenes with good to excellent yields (Scheme 4). However, it is important to note that we had to extend the reaction time up to seven days to obtain satisfying yields.…”