The title compound, 4-tert-butyl-6-（4-chlorophenyl）-3,6-dihydro-2H-1,3-thiazin- 2-iminium chloride （C14H18C12N2S）, has been synthesized by the reaction of 1-（4-chlorophenyl）- 4,4-dimethylpent-1-en-3-one with thi...The title compound, 4-tert-butyl-6-（4-chlorophenyl）-3,6-dihydro-2H-1,3-thiazin- 2-iminium chloride （C14H18C12N2S）, has been synthesized by the reaction of 1-（4-chlorophenyl）- 4,4-dimethylpent-1-en-3-one with thiourea, and its crystal structure was determined by single- crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P211c with a = 16.3064（11）, b = 9.4471（6）, c = 11.2626 （8）A, β = 108.400（1）°, Z = 4, V = 1646.28（19） A^3, Mr = 317.26, Dc = 1.280 g/cm^3, S = 1.078,μ = 0.510 mm^-1, F（000） = 664, the final R = 0.0514 and wR = 0.1412 for 3210 observed reflections （I 〉 2σ（I））. The thiazine ring system displays a twisted boat conformation, and three N-H,..Cl hydrogen bonds exist in the crystal. The combination of two N-H...Cl hydrogen bonds generate an R2^1 （6） ring.展开更多
Three new napelline-type C20-diterpenoid alkaloids,named aconicarmichinium A and B trifluoroacetates（1 and 2） and aconicarmichinium C chloride（3）,were isolated from an aqueous extract of ＂fu zi＂,the lateral root...Three new napelline-type C20-diterpenoid alkaloids,named aconicarmichinium A and B trifluoroacetates（1 and 2） and aconicarmichinium C chloride（3）,were isolated from an aqueous extract of ＂fu zi＂,the lateral roots of Aconitum carmichaelii.Their structures were elucidated by extensive spectroscopic data analysis.Compounds 1-3 represent the first examples of napelline-type C20 diterpenoid alkaloid alcohol iminiums,of which the structures were fully characterized.In addition,transformation and equilibration between the alcohol iminiums（1-3） and the aza acetals la-3a were investigated by measurements of the NMR spectra in protic and aprotic deuterium solvents including alkali pyridine-d5,along with evaporation under reduced pressure and gradual additions of TFA,AcOH,and HC1.The results demonstrated that the transformation and equilibration were solvent-,base-,and acid-dependent.Especially,in aqueous biological fluid,these C20-diterpenoid alkaloids would more likely exist as the alcohol iminiums accompanied by anion counterparts in biosystems to increase their solubility, bioavailability, transportations, and functions.The absolute configurations of 1-3 were confirmed by X-ray crystallographic analysis of 2a.展开更多
A rare arcutine-type C_（20）-diterpenoid alkaloid, named aconicarmicharcutinium A and obtained as hydroxide（1） and trifluoroacetate（1a）, was characterized as a minor constituent of ＂fu zi＂（the lateral roots of...A rare arcutine-type C_（20）-diterpenoid alkaloid, named aconicarmicharcutinium A and obtained as hydroxide（1） and trifluoroacetate（1a）, was characterized as a minor constituent of ＂fu zi＂（the lateral roots of Aconitum carmichaelii）. The structures of 1 and 1a were elucidated by comprehensive analysis of spectroscopic data including^（19）F and 2D NMR experiments. Compounds 1 and 1a represent the first examples of the arcutine-type C_（20）-diterpenoid alkaloid iminium.展开更多
Asymmetric epoxidation of olefins with oxone was first catalyzed by chiral iminium salts generated in situ from chiral amines and aldehydes. With 2S,5S-2,5-dicyclohexylaminocarbonylpyrolidine and t-butylacetaldehyde, ...Asymmetric epoxidation of olefins with oxone was first catalyzed by chiral iminium salts generated in situ from chiral amines and aldehydes. With 2S,5S-2,5-dicyclohexylaminocarbonylpyrolidine and t-butylacetaldehyde, trans-stilbene were epoxdized in 80% conversion, 93% yield and 65% e.e. at 0 ℃.展开更多
Sessiline is an alkaloid which is recently isolated from the fruits of Acanthopanax sessiliflorus. The molecule contains two five-membered heterocyclic units joined together by an acylaminocarbinol-ether type bond. He...Sessiline is an alkaloid which is recently isolated from the fruits of Acanthopanax sessiliflorus. The molecule contains two five-membered heterocyclic units joined together by an acylaminocarbinol-ether type bond. Here, we describe the first, simple synthesis of sessiline from 5-hydroxypyrrolidin-2-one and 5-hydroxymethylfurfural, which are prepared from succinimide and furfuryl alcohol, respectively. The coupling reaction takes place on moderate heating under neat conditions.展开更多
A simple primary-tertiary diamine has been explored as a novel catalyst for the Morita-Baylis-Hillman reaction of MVK and aryl aldehydes, and moderate to good chemical yields were obtained. Detailed mechanism study in...A simple primary-tertiary diamine has been explored as a novel catalyst for the Morita-Baylis-Hillman reaction of MVK and aryl aldehydes, and moderate to good chemical yields were obtained. Detailed mechanism study indicated that the diamine acted as a bifunctional cooperation catalyst via a bicyclic enamino-quaternary ammonium intermediate.展开更多
An unprecedented acetic acid-catalyzed efficient access to N-alkylpyrroles from reaction of 4-hydroxy-L-proline with a variety of aldehydes has been achieved in good to excellent yields under mild reaction conditions.
A catalytic asymmetric total synthesis of(+)-vincamine is presented. Key features of the synthesis include a Pd-catalyzed enantioselective decarboxylative allylation to form the C20 quaternary stereogenic center and a...A catalytic asymmetric total synthesis of(+)-vincamine is presented. Key features of the synthesis include a Pd-catalyzed enantioselective decarboxylative allylation to form the C20 quaternary stereogenic center and a stereoselective iminium reduction to install the critical cis-C20/C21 relative stereochemisty.展开更多
报道手性合成砌块(4S,5R)-N-苄基-4-苄氧基-5-羟甲基-2-吡咯烷酮(3a)的直接还原氰基化及产物的立体化学与转化研究.含未保护羟基的内酰胺用Li Al H4/KCN体系直接还原氰基化,生成比例为69∶31的2,5-反式/顺式非对映立体异构体.与文献类...报道手性合成砌块(4S,5R)-N-苄基-4-苄氧基-5-羟甲基-2-吡咯烷酮(3a)的直接还原氰基化及产物的立体化学与转化研究.含未保护羟基的内酰胺用Li Al H4/KCN体系直接还原氰基化,生成比例为69∶31的2,5-反式/顺式非对映立体异构体.与文献类似结果对比显示,氰基负离子对5-羟甲基-(35)-1-吡咯啉鎓中间体的加成主要受立体电子效应和C(5)位取代基(羟甲基)与进攻试剂间烯丙型1,3-位阻控制.该混合物在碱性条件下水解,生成比例为10∶90的2,5-反式/2,5-顺式-bulgecinine衍生物.这一结果表明氰基水解反应伴随着在C(2)位发生了有合成价值的串联差向异构化.由此建立了立体选择性地合成2,5-顺式(-)-N-甲基-2-别-bulgecinine的简便方法.展开更多
An unprecedented acetic acid-catalyzed efficient access to N-alkylpyrroles from reaction of 4-hydroxy-L-proline with a variety of aldehydes has been achieved in good to excellent yields under mild reaction conditions.
The dissociation chemistry of primary fragment ions from the protonated proline-containing tripeptides glycylprolylglycine,prolylglycylglycine,and prolylprolylglycine was investigated by electrospray ionization multi-...The dissociation chemistry of primary fragment ions from the protonated proline-containing tripeptides glycylprolylglycine,prolylglycylglycine,and prolylprolylglycine was investigated by electrospray ionization multi-stage mass spectrometry.Calcula-tions showed the a 2 ions generated from b 2 ions were cyclic,which is energetically more favorable than the linear form.The prolyl residue in the structure affected the energy hypersurface of the dissociation reaction from the b 2 ion to the a 2 ion.In the fragmen-tation of a 2 ions,the iminium-imine complex corresponding to loss of CO from the a 2 ion was suggested to be an ion-neutral com-plex (INC).The a 1 ion was generated from direct separation of this INC,and the internal iminium ion,which was absent in PGG,was generated from another INC that was formed from the first INC via proton-bridged complex-mediated intramolecular proton transfer.Although these intermediates are unstable,their existence is supported by experiments and density functional theory calculations.展开更多
基金supported by the National Project of Scientific and Technical Supporting Programs Funded by Ministry of Science & Technology of China (No 2006BAE01A01-4)
文摘The title compound, 4-tert-butyl-6-（4-chlorophenyl）-3,6-dihydro-2H-1,3-thiazin- 2-iminium chloride （C14H18C12N2S）, has been synthesized by the reaction of 1-（4-chlorophenyl）- 4,4-dimethylpent-1-en-3-one with thiourea, and its crystal structure was determined by single- crystal X-ray diffraction. The crystal belongs to the monoclinic system, space group P211c with a = 16.3064（11）, b = 9.4471（6）, c = 11.2626 （8）A, β = 108.400（1）°, Z = 4, V = 1646.28（19） A^3, Mr = 317.26, Dc = 1.280 g/cm^3, S = 1.078,μ = 0.510 mm^-1, F（000） = 664, the final R = 0.0514 and wR = 0.1412 for 3210 observed reflections （I 〉 2σ（I））. The thiazine ring system displays a twisted boat conformation, and three N-H,..Cl hydrogen bonds exist in the crystal. The combination of two N-H...Cl hydrogen bonds generate an R2^1 （6） ring.
基金Financial support from the National Natural Science Foundation of China (NNSFC Nos. 21132009, 30825044)the National Science and Technology Project of China (Nos. 2012ZX09301002002, 2011ZX0 9307-002-01)
文摘Three new napelline-type C20-diterpenoid alkaloids,named aconicarmichinium A and B trifluoroacetates（1 and 2） and aconicarmichinium C chloride（3）,were isolated from an aqueous extract of ＂fu zi＂,the lateral roots of Aconitum carmichaelii.Their structures were elucidated by extensive spectroscopic data analysis.Compounds 1-3 represent the first examples of napelline-type C20 diterpenoid alkaloid alcohol iminiums,of which the structures were fully characterized.In addition,transformation and equilibration between the alcohol iminiums（1-3） and the aza acetals la-3a were investigated by measurements of the NMR spectra in protic and aprotic deuterium solvents including alkali pyridine-d5,along with evaporation under reduced pressure and gradual additions of TFA,AcOH,and HC1.The results demonstrated that the transformation and equilibration were solvent-,base-,and acid-dependent.Especially,in aqueous biological fluid,these C20-diterpenoid alkaloids would more likely exist as the alcohol iminiums accompanied by anion counterparts in biosystems to increase their solubility, bioavailability, transportations, and functions.The absolute configurations of 1-3 were confirmed by X-ray crystallographic analysis of 2a.
基金Financial support from the National Natural Science Foundation of China(NNSFCNos.81630094 and 30825044)
文摘A rare arcutine-type C_（20）-diterpenoid alkaloid, named aconicarmicharcutinium A and obtained as hydroxide（1） and trifluoroacetate（1a）, was characterized as a minor constituent of ＂fu zi＂（the lateral roots of Aconitum carmichaelii）. The structures of 1 and 1a were elucidated by comprehensive analysis of spectroscopic data including^（19）F and 2D NMR experiments. Compounds 1 and 1a represent the first examples of the arcutine-type C_（20）-diterpenoid alkaloid iminium.
文摘Asymmetric epoxidation of olefins with oxone was first catalyzed by chiral iminium salts generated in situ from chiral amines and aldehydes. With 2S,5S-2,5-dicyclohexylaminocarbonylpyrolidine and t-butylacetaldehyde, trans-stilbene were epoxdized in 80% conversion, 93% yield and 65% e.e. at 0 ℃.
文摘Sessiline is an alkaloid which is recently isolated from the fruits of Acanthopanax sessiliflorus. The molecule contains two five-membered heterocyclic units joined together by an acylaminocarbinol-ether type bond. Here, we describe the first, simple synthesis of sessiline from 5-hydroxypyrrolidin-2-one and 5-hydroxymethylfurfural, which are prepared from succinimide and furfuryl alcohol, respectively. The coupling reaction takes place on moderate heating under neat conditions.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 20421202, 20632060 and 20702052)Ministry of Science and Technology of China (Grant No. 2008CB617501 & 2009ZX09501-018), and the Chinese Academy of Sciences
文摘A simple primary-tertiary diamine has been explored as a novel catalyst for the Morita-Baylis-Hillman reaction of MVK and aryl aldehydes, and moderate to good chemical yields were obtained. Detailed mechanism study indicated that the diamine acted as a bifunctional cooperation catalyst via a bicyclic enamino-quaternary ammonium intermediate.
基金support from the National Natural Science Foundation of China(20972051)the Science and Technology Commission of Shanghai Municipality(08430703900 & 08431901800)+1 种基金the 111 Project(B07023)East China University of Science & Technology
文摘An unprecedented acetic acid-catalyzed efficient access to N-alkylpyrroles from reaction of 4-hydroxy-L-proline with a variety of aldehydes has been achieved in good to excellent yields under mild reaction conditions.
基金National Natural Science Foundation of China (Nos. 21991114, 21921002 and 21732005) for financial support。
文摘A catalytic asymmetric total synthesis of(+)-vincamine is presented. Key features of the synthesis include a Pd-catalyzed enantioselective decarboxylative allylation to form the C20 quaternary stereogenic center and a stereoselective iminium reduction to install the critical cis-C20/C21 relative stereochemisty.
文摘报道手性合成砌块(4S,5R)-N-苄基-4-苄氧基-5-羟甲基-2-吡咯烷酮(3a)的直接还原氰基化及产物的立体化学与转化研究.含未保护羟基的内酰胺用Li Al H4/KCN体系直接还原氰基化,生成比例为69∶31的2,5-反式/顺式非对映立体异构体.与文献类似结果对比显示,氰基负离子对5-羟甲基-(35)-1-吡咯啉鎓中间体的加成主要受立体电子效应和C(5)位取代基(羟甲基)与进攻试剂间烯丙型1,3-位阻控制.该混合物在碱性条件下水解,生成比例为10∶90的2,5-反式/2,5-顺式-bulgecinine衍生物.这一结果表明氰基水解反应伴随着在C(2)位发生了有合成价值的串联差向异构化.由此建立了立体选择性地合成2,5-顺式(-)-N-甲基-2-别-bulgecinine的简便方法.
文摘An unprecedented acetic acid-catalyzed efficient access to N-alkylpyrroles from reaction of 4-hydroxy-L-proline with a variety of aldehydes has been achieved in good to excellent yields under mild reaction conditions.
基金supported by China National Funds for Distinguished Young scientists(21025207)the National Natural Science Foundation of China(20975092)the Zhejiang Provincial Natural Science Foundation of China(Y4100020)
文摘The dissociation chemistry of primary fragment ions from the protonated proline-containing tripeptides glycylprolylglycine,prolylglycylglycine,and prolylprolylglycine was investigated by electrospray ionization multi-stage mass spectrometry.Calcula-tions showed the a 2 ions generated from b 2 ions were cyclic,which is energetically more favorable than the linear form.The prolyl residue in the structure affected the energy hypersurface of the dissociation reaction from the b 2 ion to the a 2 ion.In the fragmen-tation of a 2 ions,the iminium-imine complex corresponding to loss of CO from the a 2 ion was suggested to be an ion-neutral com-plex (INC).The a 1 ion was generated from direct separation of this INC,and the internal iminium ion,which was absent in PGG,was generated from another INC that was formed from the first INC via proton-bridged complex-mediated intramolecular proton transfer.Although these intermediates are unstable,their existence is supported by experiments and density functional theory calculations.
