A novel organocatalytic asymmetric approach to oxazoline derivatives that proceeds through Mannich/annulation reaction of N-acylimines with 3-chlorooxindoles is presented.This strategy provides an efficient and conven...A novel organocatalytic asymmetric approach to oxazoline derivatives that proceeds through Mannich/annulation reaction of N-acylimines with 3-chlorooxindoles is presented.This strategy provides an efficient and convenient method to access enantioenriched oxazolines such as valuable chiral S,Noxazoline ligand as well as Ferrox ligand in high yields with excellent enantio–and diastereroselectivity.Furthermore,the optically active oxazoline products can be converted to valuable 1,2-amino alcohols.More importantly,the synthetic utility of this transformation is demonstrated in the expeditious assembly of chiral Phox-type ligand,which shows excellent catalytic activities.展开更多
New chiral C_2-symmetrical bis(oxazoline) compounds bearing one isobutyl-, secbutyl-, benzyl- or isopropyl-substituent at the 4-position have been prepared and characterized.
Disclosed herein is an efficient Ag-catalyzed 4+1 heteroannulation reaction of enamides withα-carbonyl sulfoxonium ylides.The diastereoselective transformation provides a practical access to a diverse range of multi-...Disclosed herein is an efficient Ag-catalyzed 4+1 heteroannulation reaction of enamides withα-carbonyl sulfoxonium ylides.The diastereoselective transformation provides a practical access to a diverse range of multi-functionalized oxazoline derivatives.The synthetic utility of the resultant tetrasubstituted oxazolines is further demonstrated by a series of useful manipulations into valuable building blocks of pharmaceutical relevance.展开更多
The synthesis of bis(oxazoline) dicarboxylate derivatives was investigated. Diethyl-aminosulfur trifluoride (DAST) was used as a convenient cyclization reagent in the synthesis of bis(oxazoline) dicarboxylate derivati...The synthesis of bis(oxazoline) dicarboxylate derivatives was investigated. Diethyl-aminosulfur trifluoride (DAST) was used as a convenient cyclization reagent in the synthesis of bis(oxazoline) dicarboxylate derivatives, which can not be obtained by the general method using MsCl and Et3N as dehydrating cyclization reagent.展开更多
Chloroamidinium salts and a-amino alcohols derived from commercially available tetraalkyl ureas and α-amino acids, respectively, can be used for the syntheses of optically active 2-（N,N-dialkylamino）oxazolines in m...Chloroamidinium salts and a-amino alcohols derived from commercially available tetraalkyl ureas and α-amino acids, respectively, can be used for the syntheses of optically active 2-（N,N-dialkylamino）oxazolines in moderate to excellent yields without any catalyst. It is a simple and mild method for the syntheses of optically active oxazolines展开更多
The present paper covers the simply and highly stereoselective syntheses of (α-S, 4S)-2-dichloromethyl-4, 5-dihydro-α-(4-nitrophenyl)-4-oxazolemethanol (4a), (α-S, 4S)-2-methyl-4, 5-dihydro-α-(4-nitrophenyl)-4-oxa...The present paper covers the simply and highly stereoselective syntheses of (α-S, 4S)-2-dichloromethyl-4, 5-dihydro-α-(4-nitrophenyl)-4-oxazolemethanol (4a), (α-S, 4S)-2-methyl-4, 5-dihydro-α-(4-nitrophenyl)-4-oxazolemethanol (4b), and (α-R, 4R)-2-dichloromethyl-4, 5-dihydro-α-[(4-methylsulfonyl)phenyl]-4-oxazolemethanol(4c) with good yields(80%—90%). A configuration inversion product, (1R, 2S)-2-dichloroacetamido-1-(4-nitrophenyl)-1, 3-propanediol (8), was obtained during our attempting to convert compound 4a into (4S, 5R)-2-(dichloromethyl)-4, 5-dihydro-5-(4-nitrophenyl)-4-oxazolemethanol(7).展开更多
The title compound, C15H22N3O9P?H2O, Mr=455.36, crystallizes in orthorhombic, space group P212121, with a =9.193(2), b =14.681(3), c =15.201(3), V =2501(1)3, Z =4, Dx=1.474g/cm3, l(MoKa)=0.71073, m=0.1894mm-1, T=2991K...The title compound, C15H22N3O9P?H2O, Mr=455.36, crystallizes in orthorhombic, space group P212121, with a =9.193(2), b =14.681(3), c =15.201(3), V =2501(1)3, Z =4, Dx=1.474g/cm3, l(MoKa)=0.71073, m=0.1894mm-1, T=2991K, F(000)=960, R=0.061 and Rw=0.068 for 1899 observed reflections with I≥3s(I). The analysis results indicate that the title compound is of lyxo-configuration and the configuration at C4 is S. In the crystal state the molecule has anti conformation about glycosidic bond with the torsion angle 151.7? the sugar ring is puckered with C3-endo-C2-exo, and the conformation of the C4C5 bond is -sc.展开更多
An efficient photocatalytic alkylation/cyclization of allylic amide with N-hydroxyphthalimide ester has been developed. The transformation is taken advantage of alkyl radicals to attack allylic amide with the assist o...An efficient photocatalytic alkylation/cyclization of allylic amide with N-hydroxyphthalimide ester has been developed. The transformation is taken advantage of alkyl radicals to attack allylic amide with the assist of inexpensive rose bengal as photocatalyst to prepare a series of alkyl substituted oxazolines in moderate to excellent yields. High regioselectivity, operational safety, mild conditions and excellent substrate generality give this protocol broad application prospects.展开更多
Excited-state intramolecular proton transfer(ESIPT) reactions of three ortho-hydroxylated oxazolines, 2-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)-phenol(DDOP), 4-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)-[1,1?-biphenyl]-3-o...Excited-state intramolecular proton transfer(ESIPT) reactions of three ortho-hydroxylated oxazolines, 2-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)-phenol(DDOP), 4-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)-[1,1?-biphenyl]-3-ol(DDOP-C_(6)H_(5)) and 4-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)-3-hydroxy-benzonitrile(DDOP-CN), have been systematically explored by density functional theory(DFT) and time-dependent density functional theory(TDDFT) methods. Two stable configurations(enol and keto forms) are found in the ground states(S_(0)) for all the compounds while the enol form only exists in the first excited states(S_(1)) for the compound modified with electron donating group(-C_(6)H_(5)). In addition, the calculated absorption and emission spectra of the compounds are in good agreements with the experiments. Infrared vibrational spectra at the hydrogen bond groups demonstrate that the intramolecular hydrogen bond O(1)-H(2)···N(3) in DDOP-C_(6)H_(5) is strengthened in the S_(1) states, while the frontier molecular orbitals further reveal that the ESIPT reactions are more likely to occur in the S_(1) states for all the compounds. Besides, the proton transfer potential energy curves show that the enol forms can barely convert into keto forms in the S_(0) states because of the high energy barriers. Meanwhile, intramolecular proton transfer of all the compounds could occur in S_(1) states. The ESIPT reactions of the ortho-hydroxylated oxazolines are barrierless processes for unsubstituted DDOP and electron withdrawing substituted DDOP-CN, while the electron donating substituted DDOP-C_(6)H_(5) has a small barrier, so the electron donating is unfavorable to the ESIPT reactions of ortho-hydroxylated oxazolines.展开更多
By mechanism transformation (anionic cationic) polymerization, diblock copolymer of butadiene and 2 ethyl 2 oxazoline (PBd b PEOx) was synthesized in two steps. The first step is the polymerization of butadiene bloc...By mechanism transformation (anionic cationic) polymerization, diblock copolymer of butadiene and 2 ethyl 2 oxazoline (PBd b PEOx) was synthesized in two steps. The first step is the polymerization of butadiene block capped with ethylene oxide and its tosylation; the second step is the cationic ring opening polymerization of 2 ethyl 2 oxazoline. The products were characterized by various methods, such as IR, 1HNMR, DMA, TEM and SAXS. The results show that the obtained copolymers possess high molecular weight and narrow molecular weight distribution, and that the content of 1,4 structure was controllable.展开更多
The electronic effect of diphenylamine-linked bis(oxazoline) ligands was tuned through introduction of electron-withdrawing bromo and nitro substituents onto the 4 and 4′ position. The variation of the NH bond acidit...The electronic effect of diphenylamine-linked bis(oxazoline) ligands was tuned through introduction of electron-withdrawing bromo and nitro substituents onto the 4 and 4′ position. The variation of the NH bond acidity was determined by the different chemical shifts of NH. The catalytic activity and enantioselectivity of the modified ligands were tested in the asymmetric Friedel-Crafts alkylation of indole with β-nitrostyrene. The effect of ligand skeleton rigidity was also investigated through the synthesis of iminodibenzyl-linked bis(oxazoline) ligands and evaluation of their catalytic activity in Friedel-Crafts alkylation.展开更多
2-Oxazolines and 2-benoxazoles were synthesized in high yields from acylamino alcohols and acylaminophenols, respectively, with triphenylphosphine-2,3-dichloro-5,6-dicyanobenzoquinone （PPh3-DDQ） as the dehydrating a...2-Oxazolines and 2-benoxazoles were synthesized in high yields from acylamino alcohols and acylaminophenols, respectively, with triphenylphosphine-2,3-dichloro-5,6-dicyanobenzoquinone （PPh3-DDQ） as the dehydrating and activating reagent. The synthesis was accomplished under neutral conditions.展开更多
A series of novel chiral C 2 symmetric bis(oxazoline) ligands have been synthesized. The copper and magnesium complexes, prepared in situ from copper(II) triflate or magnesium triflate with the new enantiop...A series of novel chiral C 2 symmetric bis(oxazoline) ligands have been synthesized. The copper and magnesium complexes, prepared in situ from copper(II) triflate or magnesium triflate with the new enantiopure oxazoline ligands, were evaluated as chiral catalysts in the enantioselective Diels Alder reaction of cyclopentadiene with N crotenoyl oxazolidin 2 one. Primary results showed that diastereoselectivity up to 94% and enantioselectivity up to 68% ee for endo products were observed respectively with these ligands.展开更多
New chiral substituted 8-quinolinyl-oxazoline ligands have been synthesized and applied in the copper(I)-catalyzed asymmetric cyclopropanation of styrene with alkyl diazoacetates. The steric effect in the ligands play...New chiral substituted 8-quinolinyl-oxazoline ligands have been synthesized and applied in the copper(I)-catalyzed asymmetric cyclopropanation of styrene with alkyl diazoacetates. The steric effect in the ligands plays a significant role in the enantiocontrol in asymmetric cyclopropanation, while the electronic effect is less important.展开更多
A mixture of (S, S)-bis(oxazoline) ligand (1) with silver trifluoromethane sulfonate afforded a helical coordination polymer (2). Its structure was determined by X-ray angle-crystal diffraction.
We synthesized optically active 2-(8′-diphenylphosphino-1′-naphthyl)oxazoline ligands by palladium-catalyzed coupling reactions of (trimethylsilyl)diphenylphosphine with 2-(8′-bromo-1′-naphthyl)oxazolines, which, ...We synthesized optically active 2-(8′-diphenylphosphino-1′-naphthyl)oxazoline ligands by palladium-catalyzed coupling reactions of (trimethylsilyl)diphenylphosphine with 2-(8′-bromo-1′-naphthyl)oxazolines, which, in turn, were prepared from 8-bromo-1-naphthoyl chloride by the reaction with natural optical active amino alcohols. Pd-Catalyzed allylic alkylation reaction induced by these chiral ligands gave the allylic substituted products in high yields and moderate ee values.展开更多
Seven 2,2'-bipyridine-based oxazole derivatives have been synthesized through multi-step reactions using 2,2'-bipyridine-3,3'-dicarboxylic acid as raw material.The structures of compounds 1-6 were characte...Seven 2,2'-bipyridine-based oxazole derivatives have been synthesized through multi-step reactions using 2,2'-bipyridine-3,3'-dicarboxylic acid as raw material.The structures of compounds 1-6 were characterized by using 1H NMR,13C NMR,MS,and X-ray single crystal diffraction techniques.The results indicate that only axially chiral enantiomers were observed in the single crystal structures of products 1 and 3 synthesized from achiral amino alcohols;Using racemic amino alcohol((±)-2-aminopropanol)as the raw material,only axial chiral isomers were observed in the single crystal structure of product 2,and no racemic isomer was found.The crystal structure of product 4 based on chiral amino alcohol((S)-valinol)contains non axial chiral isomers and S-type isomers.However,the other two optically pure amino alcohols((S)-phenylpropanol,(R)-phenylpropanol)can only obtain optically pure axially chiral and chiral products 5 and 6,respectively,maintaining the configuration of the raw amino alcohol and no non axial chiral isomer is observed.The product using(±)-2-aminobutanol as the raw material cannot be determined for its absolute configuration as a single crystal of the product has not been obtained.展开更多
基金Qingdao Marine Science and Technology Center(No.2022QNLM030003–2)the Fundamental Research Funds for the Central Universities,Taishan Scholar Program of Shandong Province(No.tsqn202103152)+2 种基金National Natural Science Foundation of China(No.22201270)Natural Science Foundation of Shandong Province(No.ZR2021QB033)the National Key Research and Development Program of China(No.2022YFC2804400)for financial support。
文摘A novel organocatalytic asymmetric approach to oxazoline derivatives that proceeds through Mannich/annulation reaction of N-acylimines with 3-chlorooxindoles is presented.This strategy provides an efficient and convenient method to access enantioenriched oxazolines such as valuable chiral S,Noxazoline ligand as well as Ferrox ligand in high yields with excellent enantio–and diastereroselectivity.Furthermore,the optically active oxazoline products can be converted to valuable 1,2-amino alcohols.More importantly,the synthetic utility of this transformation is demonstrated in the expeditious assembly of chiral Phox-type ligand,which shows excellent catalytic activities.
基金the Foundation for Academic Leader by the Education Department of Hunan province.
文摘New chiral C_2-symmetrical bis(oxazoline) compounds bearing one isobutyl-, secbutyl-, benzyl- or isopropyl-substituent at the 4-position have been prepared and characterized.
基金the National Natural Science Foundation of China(No.21702106)the Natural Science Foundation of Jiangsu Province(No.BK20170967)the Start-up Grant from Nanjing Tech University(No.39839101)for financial support。
文摘Disclosed herein is an efficient Ag-catalyzed 4+1 heteroannulation reaction of enamides withα-carbonyl sulfoxonium ylides.The diastereoselective transformation provides a practical access to a diverse range of multi-functionalized oxazoline derivatives.The synthetic utility of the resultant tetrasubstituted oxazolines is further demonstrated by a series of useful manipulations into valuable building blocks of pharmaceutical relevance.
文摘The synthesis of bis(oxazoline) dicarboxylate derivatives was investigated. Diethyl-aminosulfur trifluoride (DAST) was used as a convenient cyclization reagent in the synthesis of bis(oxazoline) dicarboxylate derivatives, which can not be obtained by the general method using MsCl and Et3N as dehydrating cyclization reagent.
文摘Chloroamidinium salts and a-amino alcohols derived from commercially available tetraalkyl ureas and α-amino acids, respectively, can be used for the syntheses of optically active 2-（N,N-dialkylamino）oxazolines in moderate to excellent yields without any catalyst. It is a simple and mild method for the syntheses of optically active oxazolines
基金Supported by the Science and Technology Fundation of Wuhan City and Wuhan Red Heart K(Group) Co. Ltd.
文摘The present paper covers the simply and highly stereoselective syntheses of (α-S, 4S)-2-dichloromethyl-4, 5-dihydro-α-(4-nitrophenyl)-4-oxazolemethanol (4a), (α-S, 4S)-2-methyl-4, 5-dihydro-α-(4-nitrophenyl)-4-oxazolemethanol (4b), and (α-R, 4R)-2-dichloromethyl-4, 5-dihydro-α-[(4-methylsulfonyl)phenyl]-4-oxazolemethanol(4c) with good yields(80%—90%). A configuration inversion product, (1R, 2S)-2-dichloroacetamido-1-(4-nitrophenyl)-1, 3-propanediol (8), was obtained during our attempting to convert compound 4a into (4S, 5R)-2-(dichloromethyl)-4, 5-dihydro-5-(4-nitrophenyl)-4-oxazolemethanol(7).
基金This project was supported by the Foundation for University Key Teachers by the Ministry of Education
文摘The title compound, C15H22N3O9P?H2O, Mr=455.36, crystallizes in orthorhombic, space group P212121, with a =9.193(2), b =14.681(3), c =15.201(3), V =2501(1)3, Z =4, Dx=1.474g/cm3, l(MoKa)=0.71073, m=0.1894mm-1, T=2991K, F(000)=960, R=0.061 and Rw=0.068 for 1899 observed reflections with I≥3s(I). The analysis results indicate that the title compound is of lyxo-configuration and the configuration at C4 is S. In the crystal state the molecule has anti conformation about glycosidic bond with the torsion angle 151.7? the sugar ring is puckered with C3-endo-C2-exo, and the conformation of the C4C5 bond is -sc.
基金supported by the National Natural Science Foundation of China (No. 22078299)Zhejiang Provincial Natural Science Foundation of China (Nos. LY21B060005, LQ20B060007)+1 种基金the College of Pharmaceutical Sciences, Zhejiang University of TechnologyCollaborative Innovation Center of Yangtze River Delta Region Green Pharmaceuticals for the financial help。
文摘An efficient photocatalytic alkylation/cyclization of allylic amide with N-hydroxyphthalimide ester has been developed. The transformation is taken advantage of alkyl radicals to attack allylic amide with the assist of inexpensive rose bengal as photocatalyst to prepare a series of alkyl substituted oxazolines in moderate to excellent yields. High regioselectivity, operational safety, mild conditions and excellent substrate generality give this protocol broad application prospects.
基金supported by the National Natural Science Foundation of China(Nos.21963008 and 21767010)the Natural Science Foundation of Hubei Province(No.2018CFB650)the Postgraduate Research and Innovation Plan Project of Hubei Minzu University(No.MYK2020001)。
文摘Excited-state intramolecular proton transfer(ESIPT) reactions of three ortho-hydroxylated oxazolines, 2-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)-phenol(DDOP), 4-(4,4-dimethyl-4,5-dihydro-oxazol-2-yl)-[1,1?-biphenyl]-3-ol(DDOP-C_(6)H_(5)) and 4-(4,4-dimethyl-4,5-dihydrooxazol-2-yl)-3-hydroxy-benzonitrile(DDOP-CN), have been systematically explored by density functional theory(DFT) and time-dependent density functional theory(TDDFT) methods. Two stable configurations(enol and keto forms) are found in the ground states(S_(0)) for all the compounds while the enol form only exists in the first excited states(S_(1)) for the compound modified with electron donating group(-C_(6)H_(5)). In addition, the calculated absorption and emission spectra of the compounds are in good agreements with the experiments. Infrared vibrational spectra at the hydrogen bond groups demonstrate that the intramolecular hydrogen bond O(1)-H(2)···N(3) in DDOP-C_(6)H_(5) is strengthened in the S_(1) states, while the frontier molecular orbitals further reveal that the ESIPT reactions are more likely to occur in the S_(1) states for all the compounds. Besides, the proton transfer potential energy curves show that the enol forms can barely convert into keto forms in the S_(0) states because of the high energy barriers. Meanwhile, intramolecular proton transfer of all the compounds could occur in S_(1) states. The ESIPT reactions of the ortho-hydroxylated oxazolines are barrierless processes for unsubstituted DDOP and electron withdrawing substituted DDOP-CN, while the electron donating substituted DDOP-C_(6)H_(5) has a small barrier, so the electron donating is unfavorable to the ESIPT reactions of ortho-hydroxylated oxazolines.
文摘By mechanism transformation (anionic cationic) polymerization, diblock copolymer of butadiene and 2 ethyl 2 oxazoline (PBd b PEOx) was synthesized in two steps. The first step is the polymerization of butadiene block capped with ethylene oxide and its tosylation; the second step is the cationic ring opening polymerization of 2 ethyl 2 oxazoline. The products were characterized by various methods, such as IR, 1HNMR, DMA, TEM and SAXS. The results show that the obtained copolymers possess high molecular weight and narrow molecular weight distribution, and that the content of 1,4 structure was controllable.
基金Supported by the National Natural Science Foundation of China (Grant No. 20772006)the Program for New Century Excellent Talents in University (Grant No. NCET-07-0011)the Development Program for Distinguished Mid-Youth Teachers of Beijing Institute of Technology
文摘The electronic effect of diphenylamine-linked bis(oxazoline) ligands was tuned through introduction of electron-withdrawing bromo and nitro substituents onto the 4 and 4′ position. The variation of the NH bond acidity was determined by the different chemical shifts of NH. The catalytic activity and enantioselectivity of the modified ligands were tested in the asymmetric Friedel-Crafts alkylation of indole with β-nitrostyrene. The effect of ligand skeleton rigidity was also investigated through the synthesis of iminodibenzyl-linked bis(oxazoline) ligands and evaluation of their catalytic activity in Friedel-Crafts alkylation.
基金Project supported by National Natural Science Foundation of China （No. 20672016）.
文摘2-Oxazolines and 2-benoxazoles were synthesized in high yields from acylamino alcohols and acylaminophenols, respectively, with triphenylphosphine-2,3-dichloro-5,6-dicyanobenzoquinone （PPh3-DDQ） as the dehydrating and activating reagent. The synthesis was accomplished under neutral conditions.
文摘A series of novel chiral C 2 symmetric bis(oxazoline) ligands have been synthesized. The copper and magnesium complexes, prepared in situ from copper(II) triflate or magnesium triflate with the new enantiopure oxazoline ligands, were evaluated as chiral catalysts in the enantioselective Diels Alder reaction of cyclopentadiene with N crotenoyl oxazolidin 2 one. Primary results showed that diastereoselectivity up to 94% and enantioselectivity up to 68% ee for endo products were observed respectively with these ligands.
文摘New chiral substituted 8-quinolinyl-oxazoline ligands have been synthesized and applied in the copper(I)-catalyzed asymmetric cyclopropanation of styrene with alkyl diazoacetates. The steric effect in the ligands plays a significant role in the enantiocontrol in asymmetric cyclopropanation, while the electronic effect is less important.
基金Project supported by the National Natural Science Foundation of China (NO. 29525202), Chinese Academy of Sciences, and Shanghai Municipal Committee of Science and Technology (No. 98QA14001).
文摘A mixture of (S, S)-bis(oxazoline) ligand (1) with silver trifluoromethane sulfonate afforded a helical coordination polymer (2). Its structure was determined by X-ray angle-crystal diffraction.
文摘We synthesized optically active 2-(8′-diphenylphosphino-1′-naphthyl)oxazoline ligands by palladium-catalyzed coupling reactions of (trimethylsilyl)diphenylphosphine with 2-(8′-bromo-1′-naphthyl)oxazolines, which, in turn, were prepared from 8-bromo-1-naphthoyl chloride by the reaction with natural optical active amino alcohols. Pd-Catalyzed allylic alkylation reaction induced by these chiral ligands gave the allylic substituted products in high yields and moderate ee values.
基金supported by Guizhou Province College Students Innovation Project(S202310666114)the Student Program of Minzu Normal University of Xingyi(23XYXS28)Guizhou Province Qianxinan Prefecture Science and Technology Bureau project(2022-1-24).
文摘Seven 2,2'-bipyridine-based oxazole derivatives have been synthesized through multi-step reactions using 2,2'-bipyridine-3,3'-dicarboxylic acid as raw material.The structures of compounds 1-6 were characterized by using 1H NMR,13C NMR,MS,and X-ray single crystal diffraction techniques.The results indicate that only axially chiral enantiomers were observed in the single crystal structures of products 1 and 3 synthesized from achiral amino alcohols;Using racemic amino alcohol((±)-2-aminopropanol)as the raw material,only axial chiral isomers were observed in the single crystal structure of product 2,and no racemic isomer was found.The crystal structure of product 4 based on chiral amino alcohol((S)-valinol)contains non axial chiral isomers and S-type isomers.However,the other two optically pure amino alcohols((S)-phenylpropanol,(R)-phenylpropanol)can only obtain optically pure axially chiral and chiral products 5 and 6,respectively,maintaining the configuration of the raw amino alcohol and no non axial chiral isomer is observed.The product using(±)-2-aminobutanol as the raw material cannot be determined for its absolute configuration as a single crystal of the product has not been obtained.
