Coupling Reaction Of α-hydroxyl Ketene Dithioacetals With Carbon Nucleophiles

α-hydroxyl ketene dithioacetals possessing an allylalcohol moiety, as well as terminal bisalkylthio substituted alkene are a class of important intermediates in organic synthesis. Generally, these compounds are derived from accessibleα–oxoketen dithioacetals and the common methods of preparation involve (a) regioselective sodium borohydride 1,2-reduce ofα–oxoketen dithioacetals, (b) 1,2-nucleophilic addition of organomatals such as organomagnesium, organolithium, Reformatsky regent toα–oxoketen dithioacetals, (c) Baylis-Hillman reaction between polarized ketene dithioacetals and aldehydes. Besides, The reaction of aldehydes with dithioacetate enethiolates followed by alkylation effectively givesα-hydroxyl ketene dithioacetals.α-hydroxyl ketene dithioacetals were treated under diversely catalyzed conditions, and a wide range of significant compounds and synthetic precursors thus were obtained. Furthermore, 1,3-carbonyl transposition and cycloaromation methods through these carbinoldithioacetals were constitute and these methods are widely used in the field of organic synthesis. Using easily available, nontoxic, less costly catalyst is the necessary consideration of controlling environmental pollution. Therefore, it is important to apply such a catalyst to transformation ofα-hydroxyl ketene dithioacetals.In this thesis, nontoxic, low-cost silica gel has been shown to be an effective catalyst for electrophilic dimeric reaction ofα–hydroxyl ketene dithioacetals prepared by regioselective sodium borohydride 1,2-reduce ofα–oxoketen dithioacetals to give terminal functionalized 1,4-pentadienes and allylation of 1,3-dicarbonyl compounds with these carbinolketene dithioacetals affordingα-allyl-1,3-dicarbonyl compounds in good yield under very mild conditions. Dihydropyrans were also obtained by allylation and enolcyclization. The factors influencing the reactions mentioned and the relative mechanisms were discussed.23 new compounds were prepared in this thesis and were confirmed by IR and 1H NMR, 13C NMR.