Three chiral N-ferrocenylmethylaminoalcohols were synthesized from readily available natural L-valine, leucine and phenylanine, and used as chiral ligands in the enantioselective addition of diethylzinc to aldehydes.
Four types of chiral thiazolidine derivatives were synthesized conveniently from natural L-cysteine and showed good enantioselectivity in up to 90% ee in the addition of diethylzine to benzaldehyde. Their enantioselec...Four types of chiral thiazolidine derivatives were synthesized conveniently from natural L-cysteine and showed good enantioselectivity in up to 90% ee in the addition of diethylzine to benzaldehyde. Their enantioselectivity was affected by the bulkiness of R and the thiazolidine ring systems in their molecules.展开更多
Readily available 2-methylquinoline derived chiral ligands 1 and 2 have been applied in the enantioselective addition of diethylzinc to aldehydes with up to 91.4% ee being recorded.
Four 1, 2,3,4-tetrahydro - β - c arboline amino acid esters with a heterocycle at the C- 1position were used as chiral ligands in the enantioselective addition reactions. The differentpositions of the heteroatoms gav...Four 1, 2,3,4-tetrahydro - β - c arboline amino acid esters with a heterocycle at the C- 1position were used as chiral ligands in the enantioselective addition reactions. The differentpositions of the heteroatoms gave different effects, and medium but opposite enantioselectivitywas recorded.展开更多
（S）-（1-Benzylpyrrolidin-2-yl）diphenylmethanol and cinchonine were evaluated as promotors in the asymmetric additions of phenylacetylene to ketones, in order to prepare chiral propargylic alcohols. Good yields （up...（S）-（1-Benzylpyrrolidin-2-yl）diphenylmethanol and cinchonine were evaluated as promotors in the asymmetric additions of phenylacetylene to ketones, in order to prepare chiral propargylic alcohols. Good yields （up to 89%） and moderate enantioselectivities （up to 77.9% ee） were achieved. Addition of Ti（OPr-i）4 can significantly improve the enantioselectivity of the reaction.展开更多
This paper describes the preparation of two new optically active aliphatic β-amino alcohols (R)-5,5-dimethyl-2-(dimethy-lamino)-1,1-diphenyl-1-hexanol (1a) and (S)-8,8-dimethyl-2-(dimethylamino)-1, 1-diphenyl-1-nonan...This paper describes the preparation of two new optically active aliphatic β-amino alcohols (R)-5,5-dimethyl-2-(dimethy-lamino)-1,1-diphenyl-1-hexanol (1a) and (S)-8,8-dimethyl-2-(dimethylamino)-1, 1-diphenyl-1-nonanol (1b). They were synthesized by methylation of the corresponding β-amino alcohols 2a and 2b. Compounds la and 1b catalyze the addition of diethylzinc to various aldehydes enantioselectively. The catalyst structure-enantioselectivity relationships were discussed.展开更多
Nineβ‐cyclodextrin derivatives containing an amino group were synthesized via nucleophilic sub‐stitution from mono（6‐O‐p‐tolylsulfonyl）‐β‐cyclodextrin and used in asymmetric biomimetic Mi‐chael addition re...Nineβ‐cyclodextrin derivatives containing an amino group were synthesized via nucleophilic sub‐stitution from mono（6‐O‐p‐tolylsulfonyl）‐β‐cyclodextrin and used in asymmetric biomimetic Mi‐chael addition reactions in water at room temperature. The mechanism responsible for the moder‐ate activity and enantioselectivity of the β‐cyclodextrin derivatives was explored using nuclear magnetic resonance spectroscopy, namely 2D 1H rotating‐frame overhauser effect spectroscopy （ROESY）, ultraviolet absorption spectroscopy, and quantum chemical calculations, which provide a useful technique for investigating the formation of inclusion complexes. The effects of the pH of the reaction medium, theβ‐cyclodextrin derivative dosage, the structure of the modifying amino group, and various substrates on the yield and enantioselectivity were investigated. The results indicated that these factors had an important effect on the enantiomeric excess （ee） in the reaction system. Experiments using a competitor for inclusion complex formation showed that a hydrophobic cavity is necessary for enantioselective Michael addition. A comparison of the reactions using 4‐nitro‐β‐nitrostyrene and 2‐nitro‐β‐nitrostyrene showed that steric hindrance improved the enan‐tioselectivity. This was verified by the optimized geometries obtained from quantum chemical cal‐culations. An ee of 71%was obtained in the asymmetric Michael addition of cyclohexanone and 2‐nitro‐β‐nitrostyrene, using （S）‐2‐aminomethylpyrrolidine‐modified β‐CD as the catalyst, in an aqueous buffer solution, i.e., CH3COONa‐HCl （pH 7.5）.展开更多
A new chiral tetradentate ligand (S, S)-1, 5-bis (4-benzyloxazolin-2-yl-methyl)-1, 5-diazacyclo-octane 1 has been synthesized and the application of 1 as catalyst in the enantioselective addition of diethyl zinc to be...A new chiral tetradentate ligand (S, S)-1, 5-bis (4-benzyloxazolin-2-yl-methyl)-1, 5-diazacyclo-octane 1 has been synthesized and the application of 1 as catalyst in the enantioselective addition of diethyl zinc to benzaldehyde is also described.展开更多
A series of C_2-symmetric and asymmetric chiral thiourea derivatives were synthesized from commercial L-phenylalanine.All of the new compounds have been fully characterized by IR,~1H NMR,^（13）C NMR,MS spectra and el...A series of C_2-symmetric and asymmetric chiral thiourea derivatives were synthesized from commercial L-phenylalanine.All of the new compounds have been fully characterized by IR,~1H NMR,^（13）C NMR,MS spectra and elemental analyses.The chiral thioureas were used as chiral ligands in the catalytic enantioselective ethylation of aldehydes with diethylzinc,the corresponding sec-alcohols were gained with excellent enantioselectivities（up to 87.1%ee） and high yields（up to 76.7%） after the conditions were optimized.展开更多
A new kind of optically active polymer bearing chiral amino alcohol was prepared by means of graft. The resulting grafted polymer was obtained as follows. First, the carbonyl of optically active helical poly（menthyl ...A new kind of optically active polymer bearing chiral amino alcohol was prepared by means of graft. The resulting grafted polymer was obtained as follows. First, the carbonyl of optically active helical poly（menthyl vinyl ketone）（poly-MVK） was reduced to hydroxyl group with lithium aluminum hydride as a reductant to yield poly（1-menthyl-2-propen-1-ol）（poly-MPO）. Second, the hydroxyl group of poly-MPO reacted with epichlorohydrin to yield methyloxirane-loading poly-MPO[（poly-MPO）-MO]. Third, the（poly-MPO）-MO reacted with amine to pro- duce optically active polymer bearing chiral amino alcohol[（poly-MPO）-APO]. The （poly-MPO）-APO was applied to the asymmetric addition of phenylacetylene to aromatic ketone. Good enantioselectivities were achieved and the catalyst could be recovered and reused 5 times with unchanged enantioselectivity and slightly decreased activity.展开更多
The first example of enantioselective allylation of aldehydes with chiral allyl organolanthanide reagents has been achieved in high chemical yield and moderate optical purity (up to 54% e.e.).
Valuable chiral N-Boc-β-benzyl-β-amino acid was concisely synthesized via construction of chiral NBoc-3-benzyl-5-oxoisoxazolidine through cross-metathesis/conjugate addition/oxidation.All of the starting materials f...Valuable chiral N-Boc-β-benzyl-β-amino acid was concisely synthesized via construction of chiral NBoc-3-benzyl-5-oxoisoxazolidine through cross-metathesis/conjugate addition/oxidation.All of the starting materials for the synthesis of chiral N-Boc-β-benzyl-β-amino acid are cheap,and two-step short procedure make it easy for the rapid construction of various chiral β-arylmethyl-β-amino acids and important drugs,such as sitagliptin phosphate.展开更多
文摘Three chiral N-ferrocenylmethylaminoalcohols were synthesized from readily available natural L-valine, leucine and phenylanine, and used as chiral ligands in the enantioselective addition of diethylzinc to aldehydes.
基金This work was financially supported by the State Key Laboratory of Elemento-Organic Chemistry,Nankai University.
文摘Four types of chiral thiazolidine derivatives were synthesized conveniently from natural L-cysteine and showed good enantioselectivity in up to 90% ee in the addition of diethylzine to benzaldehyde. Their enantioselectivity was affected by the bulkiness of R and the thiazolidine ring systems in their molecules.
文摘Readily available 2-methylquinoline derived chiral ligands 1 and 2 have been applied in the enantioselective addition of diethylzinc to aldehydes with up to 91.4% ee being recorded.
文摘Four 1, 2,3,4-tetrahydro - β - c arboline amino acid esters with a heterocycle at the C- 1position were used as chiral ligands in the enantioselective addition reactions. The differentpositions of the heteroatoms gave different effects, and medium but opposite enantioselectivitywas recorded.
文摘（S）-（1-Benzylpyrrolidin-2-yl）diphenylmethanol and cinchonine were evaluated as promotors in the asymmetric additions of phenylacetylene to ketones, in order to prepare chiral propargylic alcohols. Good yields （up to 89%） and moderate enantioselectivities （up to 77.9% ee） were achieved. Addition of Ti（OPr-i）4 can significantly improve the enantioselectivity of the reaction.
文摘This paper describes the preparation of two new optically active aliphatic β-amino alcohols (R)-5,5-dimethyl-2-(dimethy-lamino)-1,1-diphenyl-1-hexanol (1a) and (S)-8,8-dimethyl-2-(dimethylamino)-1, 1-diphenyl-1-nonanol (1b). They were synthesized by methylation of the corresponding β-amino alcohols 2a and 2b. Compounds la and 1b catalyze the addition of diethylzinc to various aldehydes enantioselectively. The catalyst structure-enantioselectivity relationships were discussed.
基金supported by the National Natural Science Foundation of China (21425627,21376279)~~
文摘Nineβ‐cyclodextrin derivatives containing an amino group were synthesized via nucleophilic sub‐stitution from mono（6‐O‐p‐tolylsulfonyl）‐β‐cyclodextrin and used in asymmetric biomimetic Mi‐chael addition reactions in water at room temperature. The mechanism responsible for the moder‐ate activity and enantioselectivity of the β‐cyclodextrin derivatives was explored using nuclear magnetic resonance spectroscopy, namely 2D 1H rotating‐frame overhauser effect spectroscopy （ROESY）, ultraviolet absorption spectroscopy, and quantum chemical calculations, which provide a useful technique for investigating the formation of inclusion complexes. The effects of the pH of the reaction medium, theβ‐cyclodextrin derivative dosage, the structure of the modifying amino group, and various substrates on the yield and enantioselectivity were investigated. The results indicated that these factors had an important effect on the enantiomeric excess （ee） in the reaction system. Experiments using a competitor for inclusion complex formation showed that a hydrophobic cavity is necessary for enantioselective Michael addition. A comparison of the reactions using 4‐nitro‐β‐nitrostyrene and 2‐nitro‐β‐nitrostyrene showed that steric hindrance improved the enan‐tioselectivity. This was verified by the optimized geometries obtained from quantum chemical cal‐culations. An ee of 71%was obtained in the asymmetric Michael addition of cyclohexanone and 2‐nitro‐β‐nitrostyrene, using （S）‐2‐aminomethylpyrrolidine‐modified β‐CD as the catalyst, in an aqueous buffer solution, i.e., CH3COONa‐HCl （pH 7.5）.
文摘A new chiral tetradentate ligand (S, S)-1, 5-bis (4-benzyloxazolin-2-yl-methyl)-1, 5-diazacyclo-octane 1 has been synthesized and the application of 1 as catalyst in the enantioselective addition of diethyl zinc to benzaldehyde is also described.
基金Open-Ended Fund of the State Key Laboratory Breeding Base of Green Chemistry-Synthesis Technology
文摘A series of C_2-symmetric and asymmetric chiral thiourea derivatives were synthesized from commercial L-phenylalanine.All of the new compounds have been fully characterized by IR,~1H NMR,^（13）C NMR,MS spectra and elemental analyses.The chiral thioureas were used as chiral ligands in the catalytic enantioselective ethylation of aldehydes with diethylzinc,the corresponding sec-alcohols were gained with excellent enantioselectivities（up to 87.1%ee） and high yields（up to 76.7%） after the conditions were optimized.
基金Supported by the National Natural Science Foundation of China（No.21172186） and the Higher Education Doctoral Science Foundation of China（No.20134301110004）.
文摘A new kind of optically active polymer bearing chiral amino alcohol was prepared by means of graft. The resulting grafted polymer was obtained as follows. First, the carbonyl of optically active helical poly（menthyl vinyl ketone）（poly-MVK） was reduced to hydroxyl group with lithium aluminum hydride as a reductant to yield poly（1-menthyl-2-propen-1-ol）（poly-MPO）. Second, the hydroxyl group of poly-MPO reacted with epichlorohydrin to yield methyloxirane-loading poly-MPO[（poly-MPO）-MO]. Third, the（poly-MPO）-MO reacted with amine to pro- duce optically active polymer bearing chiral amino alcohol[（poly-MPO）-APO]. The （poly-MPO）-APO was applied to the asymmetric addition of phenylacetylene to aromatic ketone. Good enantioselectivities were achieved and the catalyst could be recovered and reused 5 times with unchanged enantioselectivity and slightly decreased activity.
基金Project supported by National Natural Science Foundation of China.
文摘The first example of enantioselective allylation of aldehydes with chiral allyl organolanthanide reagents has been achieved in high chemical yield and moderate optical purity (up to 54% e.e.).
基金financial support for this study from the National Natural Science Foundation of China (No. 21472110)
文摘Valuable chiral N-Boc-β-benzyl-β-amino acid was concisely synthesized via construction of chiral NBoc-3-benzyl-5-oxoisoxazolidine through cross-metathesis/conjugate addition/oxidation.All of the starting materials for the synthesis of chiral N-Boc-β-benzyl-β-amino acid are cheap,and two-step short procedure make it easy for the rapid construction of various chiral β-arylmethyl-β-amino acids and important drugs,such as sitagliptin phosphate.
