SYNTHESIS AND PROPERTIES OF 1,2-BENZODITHIINS

Access to the title compounds (12-14) was achieved by two different sy ntheses starting from either phenylacetylene (1) or, from benzo[b]thio phene (2) by a reaction sequence formally equivalent to the insertion of sulfur. The key intermediates in both routes are the (Z,Z)-styrene- 1,4-dithiol derivatives 4-6 and 9-11, respectively. Compared with mono cyclic 1,2-dithiins, the absorption maxima of compounds 12-14 occur at shorter wavelengths and they are significantly more stable towards su lfur extrusion. The oxidation of 12 and 14 to the sulfoxides 17a and 1 7b, and to the aldehyde 18, respectively, are reported.