Expedient Synthesis of Substituted Thieno[3,2-]thiophenes and Selenopheno[3,2-]selenophenes Through Cascade Cyclization of Alkynyl Diol Derivatives.

Thieno[3,2-]thiophenes are used as key components in optoelectronic materials, porous hydrogen-storage hosts, organic solar cells, and polymer semiconductors. A step-efficient synthetic protocol was proposed herein for obtaining multisubstituted thieno[3,2-]thiophene and selenopheno[3,2-]selenophenes in moderate to good yields via the bisulfur/biselenium cyclization of alkynyl diols with I/NaSO or selenium. Using this strategy, substitution patterns were obtained for backbone modification in functional materials.