Bromo ketene dithioacetals (5) were prepared in high yields by reaction of α,α-diacetyl ketene dithioacetals (4) with bromine catalyzed by FeBr 3 at room temperature. This new reaction is proposed involving an ipso ...Bromo ketene dithioacetals (5) were prepared in high yields by reaction of α,α-diacetyl ketene dithioacetals (4) with bromine catalyzed by FeBr 3 at room temperature. This new reaction is proposed involving an ipso electrophilic addition-deacetylation mechanism.展开更多
The α-acetyl ketene dithioacetals 2, which bear various alkylthio groups, are a kind of important intermediates in organic synthesis. In this paper, dithioacetals 2 were prepared in very high yields (90%—100%) via t...The α-acetyl ketene dithioacetals 2, which bear various alkylthio groups, are a kind of important intermediates in organic synthesis. In this paper, dithioacetals 2 were prepared in very high yields (90%—100%) via the deacetylation reaction of the corresponding α,α-diacetyl ketene dithioacetals 1 in the presence of concentrated sulfuric acid. This reaction involves an %in-situ% electrophilic addition-deacetylation mechanism and shows the nucleophilicity of the α-carbon atom in α-oxo ketenedithioacetals. Meanwhile, when the reaction time was prolonged to 22—25 h, the β-keto thiolesters 3a and 3c were produced in good yields.展开更多
A new method for the synthesis of the tit1e compounds 6 is described in this paper. Compounds 6 were obtained by an one-pot reaction process from β-dione and its analogues, 2-bromoethanol and carbon disulfide with po...A new method for the synthesis of the tit1e compounds 6 is described in this paper. Compounds 6 were obtained by an one-pot reaction process from β-dione and its analogues, 2-bromoethanol and carbon disulfide with potassium carbonate as the base. The possible mechanism is discussed. In this mechanism, a monoanion intermediate 3 is proposed, it reacts with 2-bromoethanol by a sequential nucleophilic and electrophilic reaction process to build the key intermediate 5. 6 is formed by the elimination of hydrosulfide from 5.展开更多
文摘Bromo ketene dithioacetals (5) were prepared in high yields by reaction of α,α-diacetyl ketene dithioacetals (4) with bromine catalyzed by FeBr 3 at room temperature. This new reaction is proposed involving an ipso electrophilic addition-deacetylation mechanism.
文摘The α-acetyl ketene dithioacetals 2, which bear various alkylthio groups, are a kind of important intermediates in organic synthesis. In this paper, dithioacetals 2 were prepared in very high yields (90%—100%) via the deacetylation reaction of the corresponding α,α-diacetyl ketene dithioacetals 1 in the presence of concentrated sulfuric acid. This reaction involves an %in-situ% electrophilic addition-deacetylation mechanism and shows the nucleophilicity of the α-carbon atom in α-oxo ketenedithioacetals. Meanwhile, when the reaction time was prolonged to 22—25 h, the β-keto thiolesters 3a and 3c were produced in good yields.
文摘A new method for the synthesis of the tit1e compounds 6 is described in this paper. Compounds 6 were obtained by an one-pot reaction process from β-dione and its analogues, 2-bromoethanol and carbon disulfide with potassium carbonate as the base. The possible mechanism is discussed. In this mechanism, a monoanion intermediate 3 is proposed, it reacts with 2-bromoethanol by a sequential nucleophilic and electrophilic reaction process to build the key intermediate 5. 6 is formed by the elimination of hydrosulfide from 5.
