Regiocontrolled SNAr Reaction on 2,3-Dihalopyridines with NaSMe To Obtain Bromo(methylthio)pyridines as Key Precursors of 3-Halo-2-(hetero)arylthieno[2,3-b]pyridines and Thieno[3,2-b]pyridines
摘要:
The synthesis of 3-halo-2-(hetero) arylthieno[2,3-b]pyridines and 3-halo-2-(hetero) arylthieno[3,2-b]pyridines has been performed through a three-step methodology from 3-bromo-2-chloropyridine or 2-bromo-3-fluoropyridine, respectively. The key step of this methodology is the formation of the required bromo(methylthio)pyridines by a regiocontrolled nucleophilic aromatic substitution (SNAr) with sodium methanethiolate (NaSMe). Then, the Sonogashira coupling with (hetero)arylalkynes followed by a halocyclization with bromine or iodine, afforded the expected 3-halo-2-(hetero)arylthienopyridines.
Regiocontrolled SNAr Reaction on 2,3-Dihalopyridines with NaSMe To Obtain Bromo(methylthio)pyridines as Key Precursors of 3-Halo-2-(hetero)arylthieno[2,3-b]pyridines and Thieno[3,2-b]pyridines
摘要:
The synthesis of 3-halo-2-(hetero) arylthieno[2,3-b]pyridines and 3-halo-2-(hetero) arylthieno[3,2-b]pyridines has been performed through a three-step methodology from 3-bromo-2-chloropyridine or 2-bromo-3-fluoropyridine, respectively. The key step of this methodology is the formation of the required bromo(methylthio)pyridines by a regiocontrolled nucleophilic aromatic substitution (SNAr) with sodium methanethiolate (NaSMe). Then, the Sonogashira coupling with (hetero)arylalkynes followed by a halocyclization with bromine or iodine, afforded the expected 3-halo-2-(hetero)arylthienopyridines.
Cascade Radical Annulation of 2-Alkynylthio(seleno)anisoles with Acetone or Acetonitrile: Synthesis of 3-Acetomethyl- or Cyanomethyl-Substituted Benzothio(seleno)phenes
for the direct preparation of 3-aceto(cyano)methyl-substituted benzothio(seleno)phenes has been achieved throughC(sp3)–H bondactivation of easily available acetone or acetonitrile and cascade radical cyclization reaction. In this cascade radical cyclization reaction, C(sp2)–C(sp3) and C(sp2)–S bonds, as well as benzenethio(seleno)phene skeletons, can be built along with the cleavage of the C(sp3)–S