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.
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
Chiral bis-corrole 1 and 2 were prepared by reaction of （s）-2,2′-bis（bromomethyl）-1, 1′-binaphthyl and 10-（4-hydroxylphenyl）- 5,15-bis（pentafluorophenyl）corrole or 10-（3-hydroxylphenyl）-5,15-bis（pentafluo...Chiral bis-corrole 1 and 2 were prepared by reaction of （s）-2,2′-bis（bromomethyl）-1, 1′-binaphthyl and 10-（4-hydroxylphenyl）- 5,15-bis（pentafluorophenyl）corrole or 10-（3-hydroxylphenyl）-5,15-bis（pentafluorophenyl）corrole in DMF at 60 ℃ in the presence of anhydrous K2CO3 with an isolated yield -8%. Both 1 and 2 exhibit unsymmetrical induced circular dichroism （ICD） in the soret band with positive exciton chirality.展开更多
The second-order nonlinear optical （NLO） properties of 5,10,15-triphenylcorrole （TPC）, 5,10,15,20-tetraphenylporphyrin （TPP） and L-amino acid bridged bis-corroles 1,2,3 and 4 have been calculated by using TDHF/P...The second-order nonlinear optical （NLO） properties of 5,10,15-triphenylcorrole （TPC）, 5,10,15,20-tetraphenylporphyrin （TPP） and L-amino acid bridged bis-corroles 1,2,3 and 4 have been calculated by using TDHF/PM3 method based on the RHF/6-31G （TPC and TPP） or semiempirical PM3 （1, 2, 3, 4） optimized geometries. Calculation results showed TPC and TPP have C1 and D2h symmetry, respectively when N-H protons are localized on the nitrogen atoms. TPC is the second-order NLO active chromophore due to the cancellation of centrosymmetrical structure and its first hyperpolarizability β increases to 11.524×10^-30 esu. Under electrical dipole approximation, βvalues of bis-corroles 1, 2, 3 and 4 vary from 9.831×10^-30 to 14.221×10^-30 esu, and no much improvement in the first hyperpolarizability was observed as compared to TPC monomer.However, β values of bis-corroles 1, 2, 3 and 4 are improved by about 4 times as compared to their bis-porphyrin counterparts. The analysis of β components indicates that β of this kind of bis-corroles is mainly contributed from its radial component βr. With the variation of amino acid side chains, βHRS, β,βxyz, βr and βa of bis-corroles change remarkably. Chiral L-amino acid bridged bis-corroles 2, 3 and 4 have a right-handed helix structure, and their chiral component βxyz matches βxyz ∝ r^2 ζ/L^4 （helix parameters）, showing the second-order chiral NLO response of these bis-corroles could be described by one-electron helical model theory. It was found that the radial component βr of chiral helix bis-corroles also matches βr ∝ r^2 ζ/L^4.展开更多
The mass spectrometric fragmentation of 1,8-bis [ 4-substituted （oxazolin-2-yl） ] anthracenes （AnBOXes） was investigated by using mass-analyzed ion kinetic energy spectrometry under electron-impact ionization cond...The mass spectrometric fragmentation of 1,8-bis [ 4-substituted （oxazolin-2-yl） ] anthracenes （AnBOXes） was investigated by using mass-analyzed ion kinetic energy spectrometry under electron-impact ionization conditions. All the compounds could undergo a ring contraction by the loss of an RCH = CH2 molecule to form 1-oxazirinyl-8-（oxazolin- 2-yl） anthracene ions, which could further lose an R radical, followed by the loss of oxazoline. These ions could also eliminate an R radical and subsequently undergo ring-contraction rearrangements to lose a CHCH2O fragraent and an epoxide molecule, respectively. The ions that are formed could further lose CHCH2O and CH2 = CH fragments. Several ring-contraction rearrangements of the oxazoline ring were observed under electron-impact ionization conditions.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 simple,highly effective hydrogenation of chiral BINOL to provide H_4-BINOL in multigram scale with good yield（up to 78% yield） was developed.A series of heterogeneous catalysts was tested in the hydrogenation;;the...A simple,highly effective hydrogenation of chiral BINOL to provide H_4-BINOL in multigram scale with good yield（up to 78% yield） was developed.A series of heterogeneous catalysts was tested in the hydrogenation;;the best result was obtained with 5%Pd/ C in EtOH under the H_2 pressure of 50 bar for 2 h.This method is a more useful method for practical synthesis of optically pure H4- BINOL than other available methods.展开更多
Some hymecromone derivatives containing chiral 1,1'-bi-2-naphthyl moiety were synthesized and their photodimerizations were investigated. It was found that fluorescence intensity and optical rotation of the new ch...Some hymecromone derivatives containing chiral 1,1'-bi-2-naphthyl moiety were synthesized and their photodimerizations were investigated. It was found that fluorescence intensity and optical rotation of the new chiral hymecromone derivatives could be regulated by light. This property has potential significance for developing a new type of dual-mode molecular switch.展开更多
Both enantiomers R-1 and S-1 of a chiral C60 derivative were synthesized by the reactions of C60 with 1, 1'-bi-2-naphthol bis(azidoacetates) and characterized by FD-MS, fT-IR,1H NMR, 13C NMR, UV-VIS, CD spectra.
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
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
Bi-2-naphthol(BINOL) enantiomers were baseline resolved on HPLC network-polymeric chiral stationary phase (Kromasil CHI-DMB, based on O,O′-di(3,5-dimethylbenzoyl)N,N′-diallyl-L-tartaric diamide). The effects of the ...Bi-2-naphthol(BINOL) enantiomers were baseline resolved on HPLC network-polymeric chiral stationary phase (Kromasil CHI-DMB, based on O,O′-di(3,5-dimethylbenzoyl)N,N′-diallyl-L-tartaric diamide). The effects of the column temperature, the type and the concentration of the polar alcohol modifier in the binary mobile phase on the chiral resolution were examined. The separation value was 1.191 when V(hexane)∶V(2-propanol)=95∶5 was used as mobile phase at a flow rate of 1.0 mL/min at 25 ℃ with retention time being within 14 minutes. The mechanism of the chiral recognition was discussed with the calculated thermodynamic parameters. It is suggested that hydrogen bonding interaction between hydroxyl group of the solute and the CSP play important roles in chiral recognition. The chiral resolution is enthalpy-entropy driven and the enthalpy contribution is greater. 1,1′-Bi-2-naphthyl di-p-toluenesulfonate, 1,1′-bi-2-naphthyl diacetate and 1,1′-bi-2-naphthyl dicinnamate could not be resolved at experiment conditions used.展开更多
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.
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.
基金supported by Natural Science Foundation of China(Nos.20771039 and 20572027),Research GrantCouncil of Hong Kong.
文摘Chiral bis-corrole 1 and 2 were prepared by reaction of （s）-2,2′-bis（bromomethyl）-1, 1′-binaphthyl and 10-（4-hydroxylphenyl）- 5,15-bis（pentafluorophenyl）corrole or 10-（3-hydroxylphenyl）-5,15-bis（pentafluorophenyl）corrole in DMF at 60 ℃ in the presence of anhydrous K2CO3 with an isolated yield -8%. Both 1 and 2 exhibit unsymmetrical induced circular dichroism （ICD） in the soret band with positive exciton chirality.
基金Supported by the NNSFC (20476034), Research Grants Council of Hongkong and SRF for ROCS, State Education Ministry
文摘The second-order nonlinear optical （NLO） properties of 5,10,15-triphenylcorrole （TPC）, 5,10,15,20-tetraphenylporphyrin （TPP） and L-amino acid bridged bis-corroles 1,2,3 and 4 have been calculated by using TDHF/PM3 method based on the RHF/6-31G （TPC and TPP） or semiempirical PM3 （1, 2, 3, 4） optimized geometries. Calculation results showed TPC and TPP have C1 and D2h symmetry, respectively when N-H protons are localized on the nitrogen atoms. TPC is the second-order NLO active chromophore due to the cancellation of centrosymmetrical structure and its first hyperpolarizability β increases to 11.524×10^-30 esu. Under electrical dipole approximation, βvalues of bis-corroles 1, 2, 3 and 4 vary from 9.831×10^-30 to 14.221×10^-30 esu, and no much improvement in the first hyperpolarizability was observed as compared to TPC monomer.However, β values of bis-corroles 1, 2, 3 and 4 are improved by about 4 times as compared to their bis-porphyrin counterparts. The analysis of β components indicates that β of this kind of bis-corroles is mainly contributed from its radial component βr. With the variation of amino acid side chains, βHRS, β,βxyz, βr and βa of bis-corroles change remarkably. Chiral L-amino acid bridged bis-corroles 2, 3 and 4 have a right-handed helix structure, and their chiral component βxyz matches βxyz ∝ r^2 ζ/L^4 （helix parameters）, showing the second-order chiral NLO response of these bis-corroles could be described by one-electron helical model theory. It was found that the radial component βr of chiral helix bis-corroles also matches βr ∝ r^2 ζ/L^4.
基金Supported by the National Natural Science Foundation of China(No. 20272002).
文摘The mass spectrometric fragmentation of 1,8-bis [ 4-substituted （oxazolin-2-yl） ] anthracenes （AnBOXes） was investigated by using mass-analyzed ion kinetic energy spectrometry under electron-impact ionization conditions. All the compounds could undergo a ring contraction by the loss of an RCH = CH2 molecule to form 1-oxazirinyl-8-（oxazolin- 2-yl） anthracene ions, which could further lose an R radical, followed by the loss of oxazoline. These ions could also eliminate an R radical and subsequently undergo ring-contraction rearrangements to lose a CHCH2O fragraent and an epoxide molecule, respectively. The ions that are formed could further lose CHCH2O and CH2 = CH fragments. Several ring-contraction rearrangements of the oxazoline ring were observed under electron-impact ionization conditions.
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supported by the Science and Technology Department of Zhejiang Province(no.2008C21041)was partially supported by the NSFC(no.20572101)
文摘A simple,highly effective hydrogenation of chiral BINOL to provide H_4-BINOL in multigram scale with good yield（up to 78% yield） was developed.A series of heterogeneous catalysts was tested in the hydrogenation;;the best result was obtained with 5%Pd/ C in EtOH under the H_2 pressure of 50 bar for 2 h.This method is a more useful method for practical synthesis of optically pure H4- BINOL than other available methods.
文摘Some hymecromone derivatives containing chiral 1,1'-bi-2-naphthyl moiety were synthesized and their photodimerizations were investigated. It was found that fluorescence intensity and optical rotation of the new chiral hymecromone derivatives could be regulated by light. This property has potential significance for developing a new type of dual-mode molecular switch.
文摘Both enantiomers R-1 and S-1 of a chiral C60 derivative were synthesized by the reactions of C60 with 1, 1'-bi-2-naphthol bis(azidoacetates) and characterized by FD-MS, fT-IR,1H NMR, 13C NMR, UV-VIS, CD spectra.
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.
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Bi-2-naphthol(BINOL) enantiomers were baseline resolved on HPLC network-polymeric chiral stationary phase (Kromasil CHI-DMB, based on O,O′-di(3,5-dimethylbenzoyl)N,N′-diallyl-L-tartaric diamide). The effects of the column temperature, the type and the concentration of the polar alcohol modifier in the binary mobile phase on the chiral resolution were examined. The separation value was 1.191 when V(hexane)∶V(2-propanol)=95∶5 was used as mobile phase at a flow rate of 1.0 mL/min at 25 ℃ with retention time being within 14 minutes. The mechanism of the chiral recognition was discussed with the calculated thermodynamic parameters. It is suggested that hydrogen bonding interaction between hydroxyl group of the solute and the CSP play important roles in chiral recognition. The chiral resolution is enthalpy-entropy driven and the enthalpy contribution is greater. 1,1′-Bi-2-naphthyl di-p-toluenesulfonate, 1,1′-bi-2-naphthyl diacetate and 1,1′-bi-2-naphthyl dicinnamate could not be resolved at experiment conditions used.
