Carbomethoxymethylenetriphenylar 1, or its arsonium bromide in the presence of K2CO3, reacts with 2, 2-dialkyl-1, 3-dioxa-5-substituted-benzal-4, 6-dione 2 to give cis-1-methoxycarbonyl-2-aryl-6, 6-dialky-5, 7-dioxa-s...Carbomethoxymethylenetriphenylar 1, or its arsonium bromide in the presence of K2CO3, reacts with 2, 2-dialkyl-1, 3-dioxa-5-substituted-benzal-4, 6-dione 2 to give cis-1-methoxycarbonyl-2-aryl-6, 6-dialky-5, 7-dioxa-spiro-[2, 5]-4,8-octanadione 3 with a moderate to good yield.展开更多
A stereoselective and economic synthesis of the carbapenem sidechain (2S, 4S)-4-ace-tylsulphanyl-2-[(S)1-phenylethyl-carbamoyl] pyrrolidine-1-carboxylic acid 4-nitrobenzylester was developed. Due to the effect of spat...A stereoselective and economic synthesis of the carbapenem sidechain (2S, 4S)-4-ace-tylsulphanyl-2-[(S)1-phenylethyl-carbamoyl] pyrrolidine-1-carboxylic acid 4-nitrobenzylester was developed. Due to the effect of spatial hindrance, only the (2S,4S) diastereomer 3 wasobtained by coupling 1 and the inexpensive racemic 2 catalyzed by EEDQ.展开更多
The stereoselective synthesis of 2-chloro-4-substituted-phenyl-5,5-dimethyl-1,3,2-dioxaphosphorinan-2-(thi)ones is described. Only single trans-isomers were obtained when 1-substituted-phenyl-2,2-dimethyl-1,3-propaned...The stereoselective synthesis of 2-chloro-4-substituted-phenyl-5,5-dimethyl-1,3,2-dioxaphosphorinan-2-(thi)ones is described. Only single trans-isomers were obtained when 1-substituted-phenyl-2,2-dimethyl-1,3-propanediols (1) reacted with POCl3. But the stereoselectivity of cyclization reaction between (1) and PSCl3 depended greatly upon the reaction condition. The configurational assignments and the ratio of cis-/trans- diastereoisomers of the products were performed on the basis of (HNMR)-H-1, (PNMR)-P-31 and IR spectra and confirmed by X-ray diffraction analyses.展开更多
A potent anxiolytic 4-butyl-α-agarofuran (AF-5) was synthesized from (+)dihydro-carvone. Acid catalyzed hydration of (+)dihydrocarvone and interconversion with β-O-ketone 8 and the key intermediate α,β-unsaturated...A potent anxiolytic 4-butyl-α-agarofuran (AF-5) was synthesized from (+)dihydro-carvone. Acid catalyzed hydration of (+)dihydrocarvone and interconversion with β-O-ketone 8 and the key intermediate α,β-unsaturated ketone 5 made this synthesis more practical.展开更多
A simple and convenient procedure for stercoselective synthesis of （Z）-allyl selenides has been developed by a one-pot reaction of diselenides with Baylis-Hillman adducts in the presence of samarium metal-trimethyls...A simple and convenient procedure for stercoselective synthesis of （Z）-allyl selenides has been developed by a one-pot reaction of diselenides with Baylis-Hillman adducts in the presence of samarium metal-trimethylsilyl chloride under mild conditions. Presumably, the diselenides are cleaved by Sm/TMSCI system to form selemde anions, which then undergo SN2＇ substitution of Baylis-Hillman adducts to produce the （Z）-allyl selenides.展开更多
1,4-Dienyl selenides can be stereoselectively synthesized in one pot under mild conditions in good yields by the palladiumcatalyzed hydrostannylation of acetylenic selenides, followed by Stille coupling with allylic b...1,4-Dienyl selenides can be stereoselectively synthesized in one pot under mild conditions in good yields by the palladiumcatalyzed hydrostannylation of acetylenic selenides, followed by Stille coupling with allylic bromides.展开更多
1-(4-hydroxy-3-methoxyphenyl)-2-(4-formyl-2-methoxyphenoxy)-propane-1,3-diol. A 8-O-4' neolignan, has been stereoselectively synthesized in eight steps from ferulic acid, and the directly cis opening of epoxide in...1-(4-hydroxy-3-methoxyphenyl)-2-(4-formyl-2-methoxyphenoxy)-propane-1,3-diol. A 8-O-4' neolignan, has been stereoselectively synthesized in eight steps from ferulic acid, and the directly cis opening of epoxide in eposidation and Mitsunobu reaction were used ingeniously as two key steps with high stereoselectively.展开更多
The polyacetylated(4,6-dimethylpyrimidin-2-yl)1-thioglycopyrano- sides(-)were obtained in high yields with stereoselectivity by phase-transfer catalyzed synthesis,and their structures were confirmed by elemental analy...The polyacetylated(4,6-dimethylpyrimidin-2-yl)1-thioglycopyrano- sides(-)were obtained in high yields with stereoselectivity by phase-transfer catalyzed synthesis,and their structures were confirmed by elemental analysis and IR,~1H-NMR spectral data.展开更多
Optically active 3-butylphtalide of high enantiomeric excesses (up to 93% e.e.) was synthesized from the reduction of o-pentanoylbenzoic ester with borane using B-methyloxyoxazaborolidine (1b) as the chiral catalyst.
Alkynylstannanes 1 react with Cp2Zr(H)Cl (Cp=?-C5H5) giving (Z)--stannylvinyl- zirconium complexes 2, which are trapped with NBS or iodine in THF at 0C to stereoselectively afford (Z)-a-bromovinylstannanes and (E)- a-...Alkynylstannanes 1 react with Cp2Zr(H)Cl (Cp=?-C5H5) giving (Z)--stannylvinyl- zirconium complexes 2, which are trapped with NBS or iodine in THF at 0C to stereoselectively afford (Z)-a-bromovinylstannanes and (E)- a-iodovinylstannanes 3, respectively.展开更多
An efficient and stereoselective four step synthesis of (-)-Massoialactone (1) is described. The key step involves deoxygenation of one alpha,beta - unsaturated carbonyl group in compound 5.
Z)-á-Bromovinylstannanes undergo the cross-coupling reaction with alkynyl iodides in the presence of Pd(PPh3)4 and CuI in THF at room temperature to afford stereoselectively (E)-1, 3- enynyl bromides in good yields.
1α- and 1β-methyl agarofuran 1 and 2 were stereoselectively synthesized. the key intermediates being synthesized through stereoselective Robinson annulation.The conjugated double bond was redined in an improved way...1α- and 1β-methyl agarofuran 1 and 2 were stereoselectively synthesized. the key intermediates being synthesized through stereoselective Robinson annulation.The conjugated double bond was redined in an improved way. Alkylation of imine 7 with enone 8, 9, 10 was performed展开更多
Z)-a-Selanyl alkenyl Grignard reagents 2 were prepared conveniently by treatment of a-bromovinylselenides 1 with magnesium filings in THF. Intermediates 2 were reacted with alkyl iodides in the presence of CuI or Pd(...Z)-a-Selanyl alkenyl Grignard reagents 2 were prepared conveniently by treatment of a-bromovinylselenides 1 with magnesium filings in THF. Intermediates 2 were reacted with alkyl iodides in the presence of CuI or Pd(PPh3)4 to afford (Z)-1,2-disubstituted vinylselenides 3, which were cross-coupled with Grignard reagents in the presence of (PPh3)2NiCl2 to give trisubstituted alkenes 4 stereoselectively in good yields.展开更多
Two practical methods for highly stereoselective synthesis of (Z)-2-acylamido-4-phenylcrotonates 2a similar to b have been developed. The key step in the first route was how to control the acid-catalyzed isomerization...Two practical methods for highly stereoselective synthesis of (Z)-2-acylamido-4-phenylcrotonates 2a similar to b have been developed. The key step in the first route was how to control the acid-catalyzed isomerization of condensation mixtures of alpha-keto ester 5 with carbomite. In the second route the key step was reduction of oxime 8, derived from alpha-keto ester 5, with iron powder in the presence of acetic anhydride.展开更多
By previously reported modified Masai-Rausch method of synthesizing titanocenocycles,followed by acid hydrolysis,trisubstituted al-kenes were synthesized,yields obtained are higher than that reported in literatures.St...By previously reported modified Masai-Rausch method of synthesizing titanocenocycles,followed by acid hydrolysis,trisubstituted al-kenes were synthesized,yields obtained are higher than that reported in literatures.Starting from unsymmetrical alkyne substrates,twelve different types of substituted alkenes were synthesized,among which only two were found single component,others were of mixed isomers.Beside conventional analytical methods,the NMR spectral analysis of titanocenoheterocycle intermediates and the products were used to identify the isomeric structures as well as their relative contents.展开更多
A series of new ω-azolylalkenes 3 were synthesized by N-alkylation of ffobromoalkenes 2 which were obtained by Witting reaction of ω-hydroxyalkylphosphonium bromide with aromatic aldehydes and subsequent bromination...A series of new ω-azolylalkenes 3 were synthesized by N-alkylation of ffobromoalkenes 2 which were obtained by Witting reaction of ω-hydroxyalkylphosphonium bromide with aromatic aldehydes and subsequent bromination. The structures of products were confirmed by 1HNMR, IR,MS and elemental analysis. The preliminary bioassay indicated that some of them had high flingicidal activities.展开更多
The acetylated glycopyranosyl azides were obtained in high yields with stereoselectivity by phase-transfer catalyzed(PTC) synthesis,and their structures were confirmed depending upon elemental analysis and IR,~1H,^(13...The acetylated glycopyranosyl azides were obtained in high yields with stereoselectivity by phase-transfer catalyzed(PTC) synthesis,and their structures were confirmed depending upon elemental analysis and IR,~1H,^(13)C-NMR spectral data.展开更多
Aryl telluroesters were prepared from the reaction of tellurium and Grignard reagents then acylation with acyl chlorides. Addition of telluroesters to arylpropiolates produced (2Z)-β-aryltelluro-α, β-unsaturated es...Aryl telluroesters were prepared from the reaction of tellurium and Grignard reagents then acylation with acyl chlorides. Addition of telluroesters to arylpropiolates produced (2Z)-β-aryltelluro-α, β-unsaturated esters with high stereoselectivity.展开更多
文摘Carbomethoxymethylenetriphenylar 1, or its arsonium bromide in the presence of K2CO3, reacts with 2, 2-dialkyl-1, 3-dioxa-5-substituted-benzal-4, 6-dione 2 to give cis-1-methoxycarbonyl-2-aryl-6, 6-dialky-5, 7-dioxa-spiro-[2, 5]-4,8-octanadione 3 with a moderate to good yield.
文摘A stereoselective and economic synthesis of the carbapenem sidechain (2S, 4S)-4-ace-tylsulphanyl-2-[(S)1-phenylethyl-carbamoyl] pyrrolidine-1-carboxylic acid 4-nitrobenzylester was developed. Due to the effect of spatial hindrance, only the (2S,4S) diastereomer 3 wasobtained by coupling 1 and the inexpensive racemic 2 catalyzed by EEDQ.
文摘The stereoselective synthesis of 2-chloro-4-substituted-phenyl-5,5-dimethyl-1,3,2-dioxaphosphorinan-2-(thi)ones is described. Only single trans-isomers were obtained when 1-substituted-phenyl-2,2-dimethyl-1,3-propanediols (1) reacted with POCl3. But the stereoselectivity of cyclization reaction between (1) and PSCl3 depended greatly upon the reaction condition. The configurational assignments and the ratio of cis-/trans- diastereoisomers of the products were performed on the basis of (HNMR)-H-1, (PNMR)-P-31 and IR spectra and confirmed by X-ray diffraction analyses.
文摘A potent anxiolytic 4-butyl-α-agarofuran (AF-5) was synthesized from (+)dihydro-carvone. Acid catalyzed hydration of (+)dihydrocarvone and interconversion with β-O-ketone 8 and the key intermediate α,β-unsaturated ketone 5 made this synthesis more practical.
基金Project (No. 2004C21032) supported by the Key Technologies R &D Program of Zhejiang Province, China
文摘A simple and convenient procedure for stercoselective synthesis of （Z）-allyl selenides has been developed by a one-pot reaction of diselenides with Baylis-Hillman adducts in the presence of samarium metal-trimethylsilyl chloride under mild conditions. Presumably, the diselenides are cleaved by Sm/TMSCI system to form selemde anions, which then undergo SN2＇ substitution of Baylis-Hillman adducts to produce the （Z）-allyl selenides.
基金the National Natural Science Foundation of China (No.20462002)Natural Science Foundation of Jiangxi Province (No.2007GZW0172) for financial support.
文摘1,4-Dienyl selenides can be stereoselectively synthesized in one pot under mild conditions in good yields by the palladiumcatalyzed hydrostannylation of acetylenic selenides, followed by Stille coupling with allylic bromides.
基金the National Natural Science Foundation of China (No.29972015).
文摘1-(4-hydroxy-3-methoxyphenyl)-2-(4-formyl-2-methoxyphenoxy)-propane-1,3-diol. A 8-O-4' neolignan, has been stereoselectively synthesized in eight steps from ferulic acid, and the directly cis opening of epoxide in eposidation and Mitsunobu reaction were used ingeniously as two key steps with high stereoselectively.
文摘The polyacetylated(4,6-dimethylpyrimidin-2-yl)1-thioglycopyrano- sides(-)were obtained in high yields with stereoselectivity by phase-transfer catalyzed synthesis,and their structures were confirmed by elemental analysis and IR,~1H-NMR spectral data.
文摘Optically active 3-butylphtalide of high enantiomeric excesses (up to 93% e.e.) was synthesized from the reduction of o-pentanoylbenzoic ester with borane using B-methyloxyoxazaborolidine (1b) as the chiral catalyst.
文摘Alkynylstannanes 1 react with Cp2Zr(H)Cl (Cp=?-C5H5) giving (Z)--stannylvinyl- zirconium complexes 2, which are trapped with NBS or iodine in THF at 0C to stereoselectively afford (Z)-a-bromovinylstannanes and (E)- a-iodovinylstannanes 3, respectively.
文摘An efficient and stereoselective four step synthesis of (-)-Massoialactone (1) is described. The key step involves deoxygenation of one alpha,beta - unsaturated carbonyl group in compound 5.
文摘Z)-á-Bromovinylstannanes undergo the cross-coupling reaction with alkynyl iodides in the presence of Pd(PPh3)4 and CuI in THF at room temperature to afford stereoselectively (E)-1, 3- enynyl bromides in good yields.
文摘1α- and 1β-methyl agarofuran 1 and 2 were stereoselectively synthesized. the key intermediates being synthesized through stereoselective Robinson annulation.The conjugated double bond was redined in an improved way. Alkylation of imine 7 with enone 8, 9, 10 was performed
文摘Z)-a-Selanyl alkenyl Grignard reagents 2 were prepared conveniently by treatment of a-bromovinylselenides 1 with magnesium filings in THF. Intermediates 2 were reacted with alkyl iodides in the presence of CuI or Pd(PPh3)4 to afford (Z)-1,2-disubstituted vinylselenides 3, which were cross-coupled with Grignard reagents in the presence of (PPh3)2NiCl2 to give trisubstituted alkenes 4 stereoselectively in good yields.
文摘Two practical methods for highly stereoselective synthesis of (Z)-2-acylamido-4-phenylcrotonates 2a similar to b have been developed. The key step in the first route was how to control the acid-catalyzed isomerization of condensation mixtures of alpha-keto ester 5 with carbomite. In the second route the key step was reduction of oxime 8, derived from alpha-keto ester 5, with iron powder in the presence of acetic anhydride.
文摘By previously reported modified Masai-Rausch method of synthesizing titanocenocycles,followed by acid hydrolysis,trisubstituted al-kenes were synthesized,yields obtained are higher than that reported in literatures.Starting from unsymmetrical alkyne substrates,twelve different types of substituted alkenes were synthesized,among which only two were found single component,others were of mixed isomers.Beside conventional analytical methods,the NMR spectral analysis of titanocenoheterocycle intermediates and the products were used to identify the isomeric structures as well as their relative contents.
文摘A series of new ω-azolylalkenes 3 were synthesized by N-alkylation of ffobromoalkenes 2 which were obtained by Witting reaction of ω-hydroxyalkylphosphonium bromide with aromatic aldehydes and subsequent bromination. The structures of products were confirmed by 1HNMR, IR,MS and elemental analysis. The preliminary bioassay indicated that some of them had high flingicidal activities.
文摘The acetylated glycopyranosyl azides were obtained in high yields with stereoselectivity by phase-transfer catalyzed(PTC) synthesis,and their structures were confirmed depending upon elemental analysis and IR,~1H,^(13)C-NMR spectral data.
文摘Aryl telluroesters were prepared from the reaction of tellurium and Grignard reagents then acylation with acyl chlorides. Addition of telluroesters to arylpropiolates produced (2Z)-β-aryltelluro-α, β-unsaturated esters with high stereoselectivity.
