¦¡-carbonyl Disulfide Reduction Enone Vilsmeier-haack,-arnold Reaction

a-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.In our continuing studies, we recognized the importance of the a-functionalization of these intermediates and the adjustment of alkylthio groups and Vilsmeier reagents were thus chosen to react with a-oxo ketenedithioacetals. The Vilsmeier-Haack-Arnold reactions of a-oxo ketenedithioacetals were investigated and the following work was done in this paper.1. Halogenation or haloformylation reactions of a-oxo ketenedithioacetals could be controlled through the control of the temperature and the quantity of Vilsmeier reagents. a-Halovinyl ketenedithioacetals 3a-5j and dienals 6 were obtained in moderate to high isolated yields respectively. The haloformylation reactions of a-oxo ketene dithioacetals were a kind of stereoselectivity reactions and when the dienthyl ether solutions of the products-dienals (SR=SMe, SBn) were stood at room temperature for 72 hrs, a-pyrans 7 were produced.2. The conjugated electron rich 1,1-dialktlthio enynes 9-11 were prepared simply by treating the a-halovinyl ketenedithioacetals with sodium hydroxide ethanolate.3. The intermediates-iminium salts formed from a-oxo ketene dithioacetals and Vilsmeier reagents were successfully transformed into 2-alkylthio-4-chloride pyridines 8d-81 in the presence of ammonium acetate.4. The factors influencing the reactions mentioned and the relative mechanism were discussed in this paper.Forty-one new compounds were prepared in this paper and were confirmed by IR, HNMR, MS.