The Vilsmeier Reaction Of α-Acetyl Ketene Dithioacetals And Its Applications In Organic Synthesis

α-Oxo ketenedithioacetals are applied extensively in organic synthesis as a kind of versatile intermediates and are widely studied since the space electron effects of alkylthio groups.During the course of our studies on the chemistry of α-Oxo ketene-S, S-acetals, the a-functionalization reaction of α-Oxo ketene-S, S-acetals has been developed and some valuble results have been obtained. Particularly, a series of intermediates-iminium salts I with the basic structures of ketene-S, S-acetals and olefins were prepared via a consecutive Vilsmeier-Haack starting from the easily available a-acetyl ketene-S, S-acetals under mild conditions. To get insight into the property and synthetic applications of this kind of iminium salts I, the reaction of iminium salts with various carbon nucleophiles was investigated and the main results are listed as follows.The reaction of iminium salts formed from a-acetyl ketene dithioacetals and Vilsmeier reagents with various carbon nucleophiles was carried out and the corresponding conjugated polyalkene compounds were obtained in good yields. This reaction had following advantages: (1) the readily available starting materials and cheap reagents;(2) a procedure proceeded smoothly under mild conditions. Therefore, the reaction not only expanded the synthetic applications of this kind of iminium salts I, but also provided a facile and efficient synthetic procedure for the synthesis of conjugated polyalkenes.In this paper, 13 new products were synthesized and characterized by IR, ~1H NMR, MS.