α-Oxoketene dithioacetals（ compound 1 ） are versatile synthons for organic synthesis due to their specially structural characteristic, that is, the masked ketene is conjugated with the convertible carbonyl in their...α-Oxoketene dithioacetals（ compound 1 ） are versatile synthons for organic synthesis due to their specially structural characteristic, that is, the masked ketene is conjugated with the convertible carbonyl in their molecules. Although there have been numerous reports covering the reactions in which they have been taken as 1,3-electrophiles, the reaction at the α-carbon atom of α-oxoketene dithioacetals has seldom been investigated. Junjappa and co-workers found the α- bromination of compound 2 in the presence of NBS led to α-aroyl-α-bromo ketenedithioacetals. However, the flexibility of the functional groups at the α-carbon atom of compound 2 are still limited.展开更多
A cost-effective and environmentally compliance FeCl3·6H2O catalyzed Friedel-Crafts alkylation of cyclic ketene dithioacetals with alcohols was developed. The reaction was efficient in the presence of catalyst lo...A cost-effective and environmentally compliance FeCl3·6H2O catalyzed Friedel-Crafts alkylation of cyclic ketene dithioacetals with alcohols was developed. The reaction was efficient in the presence of catalyst loading as low as 5%（molar fraction） in CH2Cl2 solvent at room temperature or under reflux conditions. A wide range of alkylated ketene dithioacetals were synthesized in excellent yields.展开更多
A FeCl3-6H2O-catalyzed synthesis of β-ketothioesters from the hydrolysis reaction of chain α-oxoketene dithioacetals was carried out. Subsequently, we explored the FeCl3-6H2O-catalyzed Friedel-Crafts alkylation of t...A FeCl3-6H2O-catalyzed synthesis of β-ketothioesters from the hydrolysis reaction of chain α-oxoketene dithioacetals was carried out. Subsequently, we explored the FeCl3-6H2O-catalyzed Friedel-Crafts alkylation of the synthesized fl-ketothioesters with alcohols in CH3CN at 25 ℃, affording the desired α-alkylated fl-ketothioesters in excellent yields. Wide scope of the substrates, use of inexpensive reagents, high yields under mild reaction conditions are notable features of these reactions.展开更多
The synthesis of 2-alkyl(aryl)-3-methylthiopyrano[4,3-c]pyrazol-4(2H)-ones via 5, 6- dihydro-2H-pyran-2, 4-dione-3-dithioacetals with (un)substituted hydrazines is described and the mechanism of the formation of title...The synthesis of 2-alkyl(aryl)-3-methylthiopyrano[4,3-c]pyrazol-4(2H)-ones via 5, 6- dihydro-2H-pyran-2, 4-dione-3-dithioacetals with (un)substituted hydrazines is described and the mechanism of the formation of title compounds is discussed. Their structures were confirmed by 1HNMR spectra and elemental analysis.展开更多
Under basic conditions, a series of 4,4-dialkylthio-l,2-diaza-l,3-butadienes were synthesized in good to excellent yields via a novel azo-coupling decarboxylation reaction by reacting a-carboxyl ketene dithioacetals w...Under basic conditions, a series of 4,4-dialkylthio-l,2-diaza-l,3-butadienes were synthesized in good to excellent yields via a novel azo-coupling decarboxylation reaction by reacting a-carboxyl ketene dithioacetals with aryldiazonium salts in aqueous medium.展开更多
Under esterification conditions, 2-(1,2-ethylenedithio) methylene-3-oxo-5-aryl-4-pentenoic acid 3 afforded the decarboxylated products 4. The triphenyltin 2-(1, 2-ethylenedithio) methylene-3-oxo-5-aryl-4-pentenoates 5...Under esterification conditions, 2-(1,2-ethylenedithio) methylene-3-oxo-5-aryl-4-pentenoic acid 3 afforded the decarboxylated products 4. The triphenyltin 2-(1, 2-ethylenedithio) methylene-3-oxo-5-aryl-4-pentenoates 5 were obtained in high yields when 3 reacted with triphenyltin hydroxide.展开更多
Stepwise oxidation of ketene dithioacetal is found and the different oxidation products changed with the amount of oxidant, temperature and reaction time.
Aliphatic α-oxo ketene cyclic dithioacetals 1 were reacted with allyl magne- sium bromide to afford the 1,2-addition products 2.Catalyzed by boron trifluoride etherate,the adducts 2 were etherified by methanol to aff...Aliphatic α-oxo ketene cyclic dithioacetals 1 were reacted with allyl magne- sium bromide to afford the 1,2-addition products 2.Catalyzed by boron trifluoride etherate,the adducts 2 were etherified by methanol to afford the corresponding methyl ethers 3.This process provides a new method for the protection of the acid sensitive hydroxyl group in 2 under mild condition.展开更多
Substituted pyrazolylpyrazoles were synthesized through the reaction of hydrazine hydrate and α-oxo-(3, 5-dimethyl-1 H-pyrazole-1-ly)ketene S, S- and N,S-Acetals which were obtained from α-oxo-(3,5-dimethyl-1 H-pyra...Substituted pyrazolylpyrazoles were synthesized through the reaction of hydrazine hydrate and α-oxo-(3, 5-dimethyl-1 H-pyrazole-1-ly)ketene S, S- and N,S-Acetals which were obtained from α-oxo-(3,5-dimethyl-1 H-pyrazole-1-yl) acetophenone. Pyrazolylpyrazole was also prepared via α-oxo ketene N,O-acetal by way of ring chain transformation.展开更多
基金Supported by the National Natural Science Foundation of China(No. 29862004) Scientific and Technological DevelopmentProgram Foundation of Jilin Province(No. 20040565).
文摘α-Oxoketene dithioacetals（ compound 1 ） are versatile synthons for organic synthesis due to their specially structural characteristic, that is, the masked ketene is conjugated with the convertible carbonyl in their molecules. Although there have been numerous reports covering the reactions in which they have been taken as 1,3-electrophiles, the reaction at the α-carbon atom of α-oxoketene dithioacetals has seldom been investigated. Junjappa and co-workers found the α- bromination of compound 2 in the presence of NBS led to α-aroyl-α-bromo ketenedithioacetals. However, the flexibility of the functional groups at the α-carbon atom of compound 2 are still limited.
基金Supported by the National Natural Science Foundation of China（No,20902010）, the Foundation of Liaoning Provincial Education Administration, China（No.L2015003） and the Science Foundation of Anshan City, China（Nos.2012KJ02, 2014KJ05）.
文摘A cost-effective and environmentally compliance FeCl3·6H2O catalyzed Friedel-Crafts alkylation of cyclic ketene dithioacetals with alcohols was developed. The reaction was efficient in the presence of catalyst loading as low as 5%（molar fraction） in CH2Cl2 solvent at room temperature or under reflux conditions. A wide range of alkylated ketene dithioacetals were synthesized in excellent yields.
基金Supported by the Fundamental Research Funds for the Jilin Province Key Laboratory of Organic Functional Molecular Design ＆ Synthesis, China（No.130028652）, the Natural Science Foundation of Liaoning Province, China（No.201602002）, the Foundation of Liaoning Province Education Administration, China（No.L2015003） and the National Natural Science Foundation of China（No.20902010）.
文摘A FeCl3-6H2O-catalyzed synthesis of β-ketothioesters from the hydrolysis reaction of chain α-oxoketene dithioacetals was carried out. Subsequently, we explored the FeCl3-6H2O-catalyzed Friedel-Crafts alkylation of the synthesized fl-ketothioesters with alcohols in CH3CN at 25 ℃, affording the desired α-alkylated fl-ketothioesters in excellent yields. Wide scope of the substrates, use of inexpensive reagents, high yields under mild reaction conditions are notable features of these reactions.
文摘The synthesis of 2-alkyl(aryl)-3-methylthiopyrano[4,3-c]pyrazol-4(2H)-ones via 5, 6- dihydro-2H-pyran-2, 4-dione-3-dithioacetals with (un)substituted hydrazines is described and the mechanism of the formation of title compounds is discussed. Their structures were confirmed by 1HNMR spectra and elemental analysis.
基金Project supported by the National Natural Science Foundation of China （No. 20272008） and the Key Grant Project of Chinese Mimstry of Eucation （No. 10412）.
文摘Under basic conditions, a series of 4,4-dialkylthio-l,2-diaza-l,3-butadienes were synthesized in good to excellent yields via a novel azo-coupling decarboxylation reaction by reacting a-carboxyl ketene dithioacetals with aryldiazonium salts in aqueous medium.
文摘Under esterification conditions, 2-(1,2-ethylenedithio) methylene-3-oxo-5-aryl-4-pentenoic acid 3 afforded the decarboxylated products 4. The triphenyltin 2-(1, 2-ethylenedithio) methylene-3-oxo-5-aryl-4-pentenoates 5 were obtained in high yields when 3 reacted with triphenyltin hydroxide.
基金This work is supported by the National Natural Science Foundation of China (No. 29972030) and the Research Fund for the Doctoral Program of Higher Education.
文摘Stepwise oxidation of ketene dithioacetal is found and the different oxidation products changed with the amount of oxidant, temperature and reaction time.
文摘Aliphatic α-oxo ketene cyclic dithioacetals 1 were reacted with allyl magne- sium bromide to afford the 1,2-addition products 2.Catalyzed by boron trifluoride etherate,the adducts 2 were etherified by methanol to afford the corresponding methyl ethers 3.This process provides a new method for the protection of the acid sensitive hydroxyl group in 2 under mild condition.
文摘Substituted pyrazolylpyrazoles were synthesized through the reaction of hydrazine hydrate and α-oxo-(3, 5-dimethyl-1 H-pyrazole-1-ly)ketene S, S- and N,S-Acetals which were obtained from α-oxo-(3,5-dimethyl-1 H-pyrazole-1-yl) acetophenone. Pyrazolylpyrazole was also prepared via α-oxo ketene N,O-acetal by way of ring chain transformation.
