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
The title compounds 3 and 4 condensed with aromatic aldehydes to give a--aroylsicinnamoyl ketene cyclic dithioacetals 5 and 6 with sodium ethoxide as the base. The stereochemistryofs and 6 was assigned as E-configurat...The title compounds 3 and 4 condensed with aromatic aldehydes to give a--aroylsicinnamoyl ketene cyclic dithioacetals 5 and 6 with sodium ethoxide as the base. The stereochemistryofs and 6 was assigned as E-configuration by 1H NMR.展开更多
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
The crystals of α,α’-dioxoketene cyclic dithioacetals were prepared and their crystal structures were determined by X-ray crystallography.The influence of bond lengths,bond angles,dihedral angles and the molecular ...The crystals of α,α’-dioxoketene cyclic dithioacetals were prepared and their crystal structures were determined by X-ray crystallography.The influence of bond lengths,bond angles,dihedral angles and the molecular conformation on different substituted cyclic dithionacetals aldehyde ketone was discussed.Compound A is Monoclinic form,P21/c Space group,Unit cell dimensions,a=0.78337（6）nm,b=O54937（4）nm,c=2.8243（2）nm,α=90°,β=90.7740（10）°,γ=90°,V=1.215（4）nm3,Z=4,Dc=1.445g/cm3,F（000）=552.Compound B is Orthorhombic form,P212121 Space group,Unit cell dimensions,a=0.5665（5）nm,b=0.7980（7）nm,c=2.924（3）nm,α=90°,β=90°,γ=90°,V=1.322（2）nm3,Z=4,Dc=1.399g/cm3,F（000）=584.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
The electrochemical and spectral properties of four α,α′-dioxoketene cyclic dithioacetals were studied.All these compounds have only one quasi-reversible peak at around-1.4—-1.6 V on platinum microelectrode.The se...The electrochemical and spectral properties of four α,α′-dioxoketene cyclic dithioacetals were studied.All these compounds have only one quasi-reversible peak at around-1.4—-1.6 V on platinum microelectrode.The self-assembled monolayer film of these compounds was prepared on gold electrode and investigated by the electrochemical impedance spectroscopy(EIS) and X-ray photoelectron spectroscopy(XPS).The cyclic voltammogram peak potential and semicircle diameter were influenced by the number of methylenes and the substituting groups at one point of a ketone.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.
文摘The title compounds 3 and 4 condensed with aromatic aldehydes to give a--aroylsicinnamoyl ketene cyclic dithioacetals 5 and 6 with sodium ethoxide as the base. The stereochemistryofs and 6 was assigned as E-configuration by 1H NMR.
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The crystals of α,α’-dioxoketene cyclic dithioacetals were prepared and their crystal structures were determined by X-ray crystallography.The influence of bond lengths,bond angles,dihedral angles and the molecular conformation on different substituted cyclic dithionacetals aldehyde ketone was discussed.Compound A is Monoclinic form,P21/c Space group,Unit cell dimensions,a=0.78337（6）nm,b=O54937（4）nm,c=2.8243（2）nm,α=90°,β=90.7740（10）°,γ=90°,V=1.215（4）nm3,Z=4,Dc=1.445g/cm3,F（000）=552.Compound B is Orthorhombic form,P212121 Space group,Unit cell dimensions,a=0.5665（5）nm,b=0.7980（7）nm,c=2.924（3）nm,α=90°,β=90°,γ=90°,V=1.322（2）nm3,Z=4,Dc=1.399g/cm3,F（000）=584.
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.
文摘The electrochemical and spectral properties of four α,α′-dioxoketene cyclic dithioacetals were studied.All these compounds have only one quasi-reversible peak at around-1.4—-1.6 V on platinum microelectrode.The self-assembled monolayer film of these compounds was prepared on gold electrode and investigated by the electrochemical impedance spectroscopy(EIS) and X-ray photoelectron spectroscopy(XPS).The cyclic voltammogram peak potential and semicircle diameter were influenced by the number of methylenes and the substituting groups at one point of a ketone.
