Regioselective Suzuki cross-coupling reactions of 2,3,4,5-tetrabromo-1-methylpyrrole

Efficient Synthesis of Substituted Selenophenes Based on the First Palladium(0)‐Catalyzed Cross‐Coupling Reactions of Tetrabromoselenophene

“…The regioselectivity is controlled by electronic and steric parameters. [20] Recently, we reported the synthesis of tetraarylthiophenes [21] and -pyrroles [22] based on regioselective Suzuki reactions of tetrabromothiophene and tetrabromo-N-methylpyrrole, respectively. Herein, we disclose our preliminary results related to Suzuki reactions of tetrabromoselenophene.…”

Double Heck Cross‐Coupling Reactions of Dibrominated Pyridines

“…The best yields were obtained with Pd(OAc) 2 and L 2 . The synthesis of 2,5-di(alkenyl)pyridines by double Heck reaction was not possible under various conditions (different catalysts and temperatures).…”

“…Pd( Ph 3 P) 4 (5 mol-%), Et 3 N, DMF, 1208, 48 h 38 49 Pd(OAc) 2 and reusable combined base, ligand, and solvent for Heck reactions. However, only traces of the product could be isolated when these conditions were applied.…”

“…The double Heck reaction of 3,5-dibromopyridine (4) with acrylates 2a -2d, 2f, and 2i -2k, using Pd(OAc) 2 and L 4 , afforded the 3,5-di(alkenyl)pyridines 5a -5h in 69 -84% yield ( Table 3). Similar yields were obtained by using ligands L 4 and L 1 .…”

Five‐Membered Heterocycles: Pyrrole and Related Systems

“…Classical cross-coupling techniques have also found new applications, further demonstrating their extraordinary synthetic potential in pyrrole chemistry. For example, tetramic acid triflates have been demonstrated to participate in Suzuki couplings at C4, giving access to 3,4-diarylpyrrolin-2-ones [734], whereas Suzuki reactions have been employed in regioselective conversion of 1-methyltetrabromopyrrole into its 5-aryl-2,3,4-tribromo-or 2,5-diaryl-3,4-dibromo-derivatives [735], or transformations involving 1-phenylsulfonyl-3,4-dibromopyrrole [736]. A reaction sequence featuring an initial iridiumcatalyzed borylation of 1-tert-butoxycarbonyl-2-trimethylsilylpyrrole at C4, followed by Suzuki coupling, as well as an intramolecular palladium-catalyzed CÀH bond functionalization at C5, has been implemented in an elegant synthesis of the alkaloid rhazinicine [737].…”