(S)-3,5-bistrifluoromethylphenyl ethanol is a key chiral intermediate for the synthesis of NK-1 receptor antagonists. Enantioselective synthesis of (S)-3,5-bistrifluoromethylphenyl ethanol was successfully performed i...(S)-3,5-bistrifluoromethylphenyl ethanol is a key chiral intermediate for the synthesis of NK-1 receptor antagonists. Enantioselective synthesis of (S)-3,5-bistrifluoromethylphenyl ethanol was successfully performed in high enantiomeric excess (e.e.) through asymmetric reduction of 3,5-bis(trifluoromethyl) acetophenone catalyzed by Candida tropicalis 104 cells. The influence of some key reaction parameters such as substrate concentration, co-substrate and its concentration, biomass and reaction time was examined, respectively. The results showed that these factors obviously influence the yield, but the optical purity of the prepared product remains intact. The opti-mum conditions for the preparation of (S)-3,5-bistrifluoromethylphenyl ethanol were found to be as follows: sub-strate concentration 50 mmol?L?1; 50 g·L-1 of maltose as co-substrate; wet cell concentration 300 g·L-1; reaction for 30 h. Under above optimal conditions, the maximum yield for (S)-3,5-bistrifluoromethylphenyl ethanol reached 70.3% with 100% of product e.e.展开更多
A series of novel bis-squaramidoacid ligands were prepared. Prochiral ketone and diketones were direct reduced by borane in the presence of these ligands giving secondary alcohol products with enantiomeric excesses u...A series of novel bis-squaramidoacid ligands were prepared. Prochiral ketone and diketones were direct reduced by borane in the presence of these ligands giving secondary alcohol products with enantiomeric excesses up to 64.2% for w-bromoacetophenone and 90.0% for 1, 6-diphenyl-1, 6-hexanedione.展开更多
Four chiral 1,1?bis(oxazolinyl)ferrocenes(1a-1d) have been prepared and used as ligands in the copper catalyzed asymmetric cyclopropanation of styrene with ethyl diazoacetate (EDA) and the magnesium catalyzed Diels-Al...Four chiral 1,1?bis(oxazolinyl)ferrocenes(1a-1d) have been prepared and used as ligands in the copper catalyzed asymmetric cyclopropanation of styrene with ethyl diazoacetate (EDA) and the magnesium catalyzed Diels-Alder reaction between 3-acryloyl-2-oxazolidinone and cyclopentadiene. Enantioselectivities up to 24% and 41%, respectively, for cyclopropanation and Diels-Alder reaction were observed.展开更多
Six new N4-[bi-（4-fluorophenyl）-methyl]-piperazine thiosemicarbazones 3a-f have been prepared starting from [bi-（4-fluorophenyl）-methyl]-piperazine in solvent-free condition under microwave irradiation with excell...Six new N4-[bi-（4-fluorophenyl）-methyl]-piperazine thiosemicarbazones 3a-f have been prepared starting from [bi-（4-fluorophenyl）-methyl]-piperazine in solvent-free condition under microwave irradiation with excellent yields. Their structures have been determined by elemental analysis, IR, MS and 1H NMR data.展开更多
Immobilizing chiral 1,1＇-bi-2-naphthol （BINOL） in one step onto polymer backbone via stable carbon-carbon bond through Suzuki reaction was achieved. The application of this immobilized chiral BINOL to the catalytic...Immobilizing chiral 1,1＇-bi-2-naphthol （BINOL） in one step onto polymer backbone via stable carbon-carbon bond through Suzuki reaction was achieved. The application of this immobilized chiral BINOL to the catalytic asymmetric oxidation of sulfide to sulfoxide exhibited good activity （up to 60% yield） and high enantioselectivity （up to 89% ee）. The immobilized chiral catalyst was very stable and could be readily reused for over 5 times without significant loss of catalytic activity and enantioselectivity.展开更多
Polymer-immobilized catalysis has many advantages such as easy recovery and reuse of catalyst. We prepared three novel chiral 1,1′-bi-2-naphthol-Ti coordination polymers with properly designed ligands and Ti(OiPr)4 u...Polymer-immobilized catalysis has many advantages such as easy recovery and reuse of catalyst. We prepared three novel chiral 1,1′-bi-2-naphthol-Ti coordination polymers with properly designed ligands and Ti(OiPr)4 under mild conditions. The prepared polymers exhibited good activity and excellent enantioselectivity (over 99%ee) in catalyzing the asymmetric oxidation of sulfides. The bridge linker in the polymer and the reaction solvent noticeably affected the enantioselectivity. The chiral coordination polymer was very stable and easy to separate from catalyzed reaction systems,with no significant loss of activity or enantioselectivity after reuse for at least ten times. These findings suggest a promising type of catalysts for synthesizing the widely used sulfoxides by asymmetrically oxidizing sulfides.展开更多
A new chiral multidenate ligand (S, S)-1,7-bis(4-benzyloxazolin-2-yl-methyl)-1, 7-diaza- 12-crown-4 1 has been synthesized and used as ligand in the copper catalyzed asymmetric cyclopropanation of 1, 1-diphenylethylene.
Experimental results are reported for the CuCl2-mediated asymmetric oxidative coupling of 2-naphthols in the presence of [-]α-methylbenzylamine to optically active （S）-（-）-1,1-bi-2-naphthol. Under anhydrous con...Experimental results are reported for the CuCl2-mediated asymmetric oxidative coupling of 2-naphthols in the presence of [-]α-methylbenzylamine to optically active （S）-（-）-1,1-bi-2-naphthol. Under anhydrous conditions and with a 3∶1 molarity ratio of α-methylbenzylamine to 2-naphthol, a fair enantioselection has been observed（up to 80.6% ee）.展开更多
A class of chiral 1,3-bis(diarylphosphinoethyl)benzenes, which are key intermediates for the synthesis of PCP-type chiral pincer ligands, were prepared in high diastereomeric ratios and excellent ee values via double ...A class of chiral 1,3-bis(diarylphosphinoethyl)benzenes, which are key intermediates for the synthesis of PCP-type chiral pincer ligands, were prepared in high diastereomeric ratios and excellent ee values via double asymmetric hydrogenation of the corresponding bis(diarylvinylphosphine oxide) substrates using a SpinPhox/Ir(I) complex as the catalyst. The hydrogenation product 5a was readily transformed into the corresponding borane-protected chiral PCP-type pincer ligand 7a with high enantiomeric excess, exemplifying a viable synthetic route to optically active chiral PCP pincer ligands.展开更多
基金Supported by the National＇Natural Science Foundation of China （21076193） and Foundation of Zhejiang Key Developing Discipline of Pharmacy （20100609）.
文摘(S)-3,5-bistrifluoromethylphenyl ethanol is a key chiral intermediate for the synthesis of NK-1 receptor antagonists. Enantioselective synthesis of (S)-3,5-bistrifluoromethylphenyl ethanol was successfully performed in high enantiomeric excess (e.e.) through asymmetric reduction of 3,5-bis(trifluoromethyl) acetophenone catalyzed by Candida tropicalis 104 cells. The influence of some key reaction parameters such as substrate concentration, co-substrate and its concentration, biomass and reaction time was examined, respectively. The results showed that these factors obviously influence the yield, but the optical purity of the prepared product remains intact. The opti-mum conditions for the preparation of (S)-3,5-bistrifluoromethylphenyl ethanol were found to be as follows: sub-strate concentration 50 mmol?L?1; 50 g·L-1 of maltose as co-substrate; wet cell concentration 300 g·L-1; reaction for 30 h. Under above optimal conditions, the maximum yield for (S)-3,5-bistrifluoromethylphenyl ethanol reached 70.3% with 100% of product e.e.
文摘A series of novel bis-squaramidoacid ligands were prepared. Prochiral ketone and diketones were direct reduced by borane in the presence of these ligands giving secondary alcohol products with enantiomeric excesses up to 64.2% for w-bromoacetophenone and 90.0% for 1, 6-diphenyl-1, 6-hexanedione.
文摘Four chiral 1,1?bis(oxazolinyl)ferrocenes(1a-1d) have been prepared and used as ligands in the copper catalyzed asymmetric cyclopropanation of styrene with ethyl diazoacetate (EDA) and the magnesium catalyzed Diels-Alder reaction between 3-acryloyl-2-oxazolidinone and cyclopentadiene. Enantioselectivities up to 24% and 41%, respectively, for cyclopropanation and Diels-Alder reaction were observed.
基金Natural Foundation of Southwest University for Nationalities(No.234688).
文摘Six new N4-[bi-（4-fluorophenyl）-methyl]-piperazine thiosemicarbazones 3a-f have been prepared starting from [bi-（4-fluorophenyl）-methyl]-piperazine in solvent-free condition under microwave irradiation with excellent yields. Their structures have been determined by elemental analysis, IR, MS and 1H NMR data.
文摘Immobilizing chiral 1,1＇-bi-2-naphthol （BINOL） in one step onto polymer backbone via stable carbon-carbon bond through Suzuki reaction was achieved. The application of this immobilized chiral BINOL to the catalytic asymmetric oxidation of sulfide to sulfoxide exhibited good activity （up to 60% yield） and high enantioselectivity （up to 89% ee）. The immobilized chiral catalyst was very stable and could be readily reused for over 5 times without significant loss of catalytic activity and enantioselectivity.
基金the Natural Science Foundation of Chongqing Science and Technology Committee (No.2007BB4442)the Science and Technology Research Project of Chongqing Education Commission (No.KJ070402)
文摘Polymer-immobilized catalysis has many advantages such as easy recovery and reuse of catalyst. We prepared three novel chiral 1,1′-bi-2-naphthol-Ti coordination polymers with properly designed ligands and Ti(OiPr)4 under mild conditions. The prepared polymers exhibited good activity and excellent enantioselectivity (over 99%ee) in catalyzing the asymmetric oxidation of sulfides. The bridge linker in the polymer and the reaction solvent noticeably affected the enantioselectivity. The chiral coordination polymer was very stable and easy to separate from catalyzed reaction systems,with no significant loss of activity or enantioselectivity after reuse for at least ten times. These findings suggest a promising type of catalysts for synthesizing the widely used sulfoxides by asymmetrically oxidizing sulfides.
文摘A new chiral multidenate ligand (S, S)-1,7-bis(4-benzyloxazolin-2-yl-methyl)-1, 7-diaza- 12-crown-4 1 has been synthesized and used as ligand in the copper catalyzed asymmetric cyclopropanation of 1, 1-diphenylethylene.
文摘Experimental results are reported for the CuCl2-mediated asymmetric oxidative coupling of 2-naphthols in the presence of [-]α-methylbenzylamine to optically active （S）-（-）-1,1-bi-2-naphthol. Under anhydrous conditions and with a 3∶1 molarity ratio of α-methylbenzylamine to 2-naphthol, a fair enantioselection has been observed（up to 80.6% ee）.
基金supported by the Basic Research Development Program of China(2010CB833300)the National Natural Science Foundation of China(21121062,21232009)+1 种基金the Chinese Academy of Sciencesthe Science and Technology Commission of Shanghai Municipality
文摘A class of chiral 1,3-bis(diarylphosphinoethyl)benzenes, which are key intermediates for the synthesis of PCP-type chiral pincer ligands, were prepared in high diastereomeric ratios and excellent ee values via double asymmetric hydrogenation of the corresponding bis(diarylvinylphosphine oxide) substrates using a SpinPhox/Ir(I) complex as the catalyst. The hydrogenation product 5a was readily transformed into the corresponding borane-protected chiral PCP-type pincer ligand 7a with high enantiomeric excess, exemplifying a viable synthetic route to optically active chiral PCP pincer ligands.
