Synthesis and Properties of Methano-Bridged Thia[15]-, Thia[17]-, and Thia[19]annulenes

Title annulenes have been synthesized through a double Wittig reaction between the vinylogous dicarbaldehydes of 1,6-diformylcycloheptatriene and bis[(triphenylphosphonio)methyl]sulfide dibromide, and their 1H NMR spectra were examined proving that the thia[17]- and - [19]annulenes sustain ring current, while the thia-[15]annulene does not.