Five-membered ring systems: thiophenes and selenium/tellurium analogs and benzo analogs

The chapter covers work published in the calendar year 2021. New methods for the ring synthesis of thiophenes, benzo[b]thiophenes, and selenophenes and tellurophenes are discussed. Novel reaction chemistry of thiophenes, benzo[b]thiophenes is covered. A selection of oligo- and polymeric thiophenes is briefly illustrated.