Flash vacuum pyrolysis (FVP) of (5-methyl-2-thiophene-yl) methyl benzoate (8) produces in ca. 75% yield 2, 5-dimethylene-2, 3-dihydrothiophene, S-monomer (3). S-Monomer 3 is relatively stable dissolved in carbon disulfide-chloroform at-78° C. The structure of 3 is confirmed by its spectral properties. When a 0.17 M solution of S-monomer 3 was allowed to warm to room temperature, SS-dimer 5 ([2, 2](2, 5) thiophenophane, 14.7%), SSS-trimer 7 ...