Regioselective Synthesis Of 3(2H)-furanones And γ-pyrones & Research On Ag(Ⅰ)-catalyzed Reaction Of Alkynyltrimethylsilanes

The synthesis of α,β-acetylenic carbonyl derivatives(ynones) and their applicatons in the synthesis of heterocyclics have been exploited in this paper. The mechanisms of these reactions have been proposed. In addition, the silver(I)-catalyzed reactions of various alkynyltrimethylsilanes have also been studied. This thesis consists of three parts.1. Different methods for preparation of ynones and application in organic synthesis have been summarized, and applications of alkynyltrimethylsilanes have been described.2. 1,2-Addition of titanium enolate derived from 2-diazo-1,3-dioxo-butanones with alkynyl alhydes has been explored. The oxidative transformation of 2-diazo-3-oxo-5-hydroxy-6-ynoates(ynones, ynamide) into 2-diazo-3,5-dioxo-6-ynoates(ynones, ynamide) has also been exploited. In addition, the regioselective reversal in the cyclization of 2-diazo-3,5-dioxo-6-ynoates(ynones, ynamide) based solely on subtle catalyst and solvent selection, which creates the two distinct types of important molecules(3(2H)-Furanones and g-Pyrones) from identical starting materials, has been studied. Through the investigation of various siver(I) salts and solvent, the optimized reaction conditions were obtained to be include Ag OAc(10 mol%) as the catalyst, DCE as solvent and 1 equivalent of Et3 N as base. In contrast, the optimal conditions for the formation of the desired g-pyrones were to use Ag Sb F6(10 mol%) as catalyst and Me OH as solvent. The reactions with various substrates provided the corresponding 3(2H)-furanones or g-pyrones in 89-98% yield.3. The effect of silver(I) salts and solvent on the reaction of alkynyltrimethylsilanes and(diacetoxyiodo)benzene has been explored. The optimal reaction obtained as blow: wet acetonitrile as solvent, 30℃, 10 mol% Ag OAc and KF as co-catalyst, 1:1 molar ratio of alkynyltrimethylsilanes to(diacetoxyiodo)benzene. The reactions with various alkynyltrimethylsilanes provided the corresponding a-acetoxy carbonyl compounds. Alkynyl group and alkenyl group were not involved in the reaction.A total of 105 compounds(including 92 new compounds) were synthesized. All new compounds were determined by IR, 1H NMR, 13 C NMR and MS.