Bildung von 1,2,4‐Trithiolanen in Dreikomponenten‐Gemischen aus Phenyl‐azid, aromatischen Thioketonen und 2,2,4,4‐Tetramethylcyclobutanthionen: Eine Schwefel‐Transfer‐Reaktion unter Bildung von ‘Thiocarbonylthiolaten’ ((Alkylidensulfonio)thiolaten) als reaktive Zwischenstufen

Formation of 1,2,4‐Trithiolanes in Three‐Component Reactions of Phenyl Azide, Aromatic Thiones, and 2,2,4,4‐Tetramethylcyclobutanethiones: A Sulfur‐Transfer Reaction to ‘Thiocarbonyl‐thiolates’ ((Alkylidenesulfonio)‐thiolates) as Reactive Intermediates The reaction of PhN3 and aromatic thioketones 18 (two‐component reaction) at 80° yields only the corresponding imines 22, S, and N2. Under similar conditions, in the presence of sterically crowded 2,2,4,4‐tetramethyl‐cyclobutanethiones 19 (three‐component reaction), 1,2,4‐trithiolanes of type 20 are formed in good yields in addition to imines 22 (Scheme 4). In case of 19a and 19c (X = CO, CS), the symmetrical trithiolanes 21a and 21b, respectively, are also isolated. With 4,4‐dimethyl‐2‐phenyl‐1,3‐thiazole‐5(4H)‐thione (24) instead of aromatic thioketone 18, imine 25, trithiolane 21a, and 1,4,2‐dithiazolidine 26 are formed (Scheme 5). A reaction mechanism for the formation of 1,2,4‐trithiolanes 20 and 21, including an S‐transfer to generate ‘thiocarbonyl‐thiolates’ 2b and/or 2c and 1,3‐dipolar cycloaddition with a thioketone, is proposed in Scheme 7.