Die Thermolyse oxidierter 1,3‐Dithiolane: Ein neuer Syntheseweg für Thiocarbonyl‐Verbindungen und Sulfine

Thermolysis of Oxidized 1.3‐Dithiolanes: A New Route for the Synthesis of Thiocarbonyl Compounds and Sulfines CF3,‐substituted 1,3‐dithiolanes 3a–c could be synthesized and subsequently oxidized to the 1,3‐dithiolane 1‐oxides 4b,c, 1,1‐dioxides 5a‐c and 1,1,3,3‐tetroxide 6b. The thioketones CF3(R)C=S (R = C6H5, 9a; CH3, 9b) and the trifluorothioacetaldehyde (9c) could be obtained in good yields by flash vacuum pyrolysis of 5a–c. By further oxidation of 5a–c the 1,3‐dithiolane 1,1,3‐trioxides were formed, and by their pyrolysis the sulfines CF3(R)C = SO (R = C6H5, 10a; CH3, 10b) were prepared. A unique rearrangement of 7b led to the 1,4‐dithiane 1,1,4‐trioxide 8b. Various Diels‐Alder adducts were synthesized for chemical proof of the existence of 9a–c and 10a, b, and stereochemical considerations are presented.