Organoselenium compounds,due to their high structural diversity,special function,and biological activities,have drawn attention in synthetic chemistry.Herein,a novel example of chiral N,N′-dioxide/cobalt(Ⅱ)complex c...Organoselenium compounds,due to their high structural diversity,special function,and biological activities,have drawn attention in synthetic chemistry.Herein,a novel example of chiral N,N′-dioxide/cobalt(Ⅱ)complex catalyzed asymmetric[2,3]-sigmatropic rearrangement of allylic selenides withα-diazo pyrazoleamides is disclosed,which represents a highly efficient approach to optically active selenides bearing a quaternary C–Se stereocenter.Most of the reactions proceed with 0.5–2 mol%catalyst loading in an inert-free gas atmosphere,and a wealth of chiral selenides are obtained in up to 99% yield and 97%enantiomeric excess(ee).The control experiments demonstrate the high reactivity of allylic selenides,as well as the conspicuous superiority of chiral N,N′-dioxide ligand andα-diazo pyrazoleamide in[2,3]-sigmatropic rearrangement.The mechanism studies reveal that the key to asymmetric rearrangement of allylic selenium ylides is the transfer of chirality from the stable chiral selenium to the carbon of the product.A feasible catalytic cycle is proposed as well.展开更多
The first investigation on catalytic asymmetric [2,3]-sigmatrop-ic rearrangement of sulfur ylides generated from carbenoids and allenic phenyl sulfide was carried out. Up to 55% ee value was obtained.
Under mild conditions, conversion of a variety of ketoximes and aldoximes to their corresponding amides and nitriles proceeded in the presence of PEG-SO3H with high yields.
The rearrangement reaction of 2-benzothiazolylthioacetyl hydrazide 1 with potassium hydroxide and carbon disulfide in ethanol to produce s-triazolo[3, 4-b]benzothiazole-3-thiol 3 was described. 3 also can be obtained...The rearrangement reaction of 2-benzothiazolylthioacetyl hydrazide 1 with potassium hydroxide and carbon disulfide in ethanol to produce s-triazolo[3, 4-b]benzothiazole-3-thiol 3 was described. 3 also can be obtained from 2-benzothiazolylhydazine 2 and the two methods for getting 3 were compared. Mannich reaction of compounds 3 was reported too.展开更多
The AIEt3-promoted tandem reductive rearrangement reactions of epoxides was studied at B3LYP/6- 31C（d,p） level. For the model compound α-hydroxy epoxides, two possible reaction pathways Ⅰ and Ⅱ were calculated. T...The AIEt3-promoted tandem reductive rearrangement reactions of epoxides was studied at B3LYP/6- 31C（d,p） level. For the model compound α-hydroxy epoxides, two possible reaction pathways Ⅰ and Ⅱ were calculated. The main difference is the order of ethylene release and six- to five-member ring rearrangement. The ring contraction rearrangement in pathway Ⅰ is the first step and this step is the rate controlling step with a free energy barrier of 116.62 kJ/mol. For pathway Ⅱ, the ethylene release occurs first, and is followed by a six-member ring opening reaction which is the rate controlling step, and the barrier is 251.38 kJ/mol. The reason for such high barrier is that the ethylene release results in the following reaction being more difficult. The results show that pathway Ⅰ （C-C rearrangement and then ethylene release） is more favorable, which is consistent with experimental results.展开更多
Theoretical calculations of the [2,3]-sila-wittig rearrangement of isomers of [（allyloxy）silyl]lithium （C3H5O）HzSiLi have been performed in the gas phase and THF solvent using the G3MP2B3 method. Seven isomers of ...Theoretical calculations of the [2,3]-sila-wittig rearrangement of isomers of [（allyloxy）silyl]lithium （C3H5O）HzSiLi have been performed in the gas phase and THF solvent using the G3MP2B3 method. Seven isomers of silylenoid （C3H5O）H2SiLi, 1-7, are found. The [2,3]-silawittig rearrangement paths are followed using two isomers, 2 and 4, to yield the transition states as well as the products. In the transition state, the silicon center functions as a nucleophile and the aUyl as an electrophile. The interaction between the silicon and allylic sites leads to the formation of SiC（3） bond and the break of O-C（1） bond. Finally, the （allylsilyl）oxylithium （C3H5）H2SiOLi is obtained. The rearrangement paths are confirmed by the intrinsic reaction coordinate （IRC） calculations. The rearrangement mechanisms of reactions of 2 and 4 are similar, and the latter reaction is more favored in the gas phase and THF solvent. Also, the solvent effects are analyzed in this work.展开更多
By the Grignard reaction of 1,1-di-deutero-1-bromobutane with phthalaldehydic acid 1',1'-di-deutero-3-n-butyl phthalide was obtained, which underwent a rearrangement reaction using AlCl3 as catalyst in CS2 to ...By the Grignard reaction of 1,1-di-deutero-1-bromobutane with phthalaldehydic acid 1',1'-di-deutero-3-n-butyl phthalide was obtained, which underwent a rearrangement reaction using AlCl3 as catalyst in CS2 to give 1-methyl-5-carboxy-3,4-di-deutero-tetrahydronaphthalene. The mechanism was proposed to be a series of consecutive 1,2- hydride transfers rather than a direct 1,4-hydride transfer.展开更多
The addition of platinum over the B2O3/TiO2-ZrO2 remarkably enhanced its catalytic stability in the vapor phase Beckmann rearrangement of cyclohexanone oxime under the carder gas of H2. The content of coke deposited ...The addition of platinum over the B2O3/TiO2-ZrO2 remarkably enhanced its catalytic stability in the vapor phase Beckmann rearrangement of cyclohexanone oxime under the carder gas of H2. The content of coke deposited on catalyst surface was decreased from 1.92% over the B2O3/TiO2-ZrO2 to 1.14% over the platinum promoted B2O3/TiO2-ZrO2 after reaction of six hours. This result indicates that the platinum added on the B2O3/TiO2-ZrO2 catalyst plays an important role in reducing the coke formation on the catalyst surface.展开更多
The configuration of the hydroxy acid 2, a product from base-catalyzed autoxidation of 3α,5-cyclo-5α-cholestane-6-one,was established on the basis of NMR techniques and the mechanism of the formation of 2 was discus...The configuration of the hydroxy acid 2, a product from base-catalyzed autoxidation of 3α,5-cyclo-5α-cholestane-6-one,was established on the basis of NMR techniques and the mechanism of the formation of 2 was discussed.展开更多
The rearrangement of 3-butylphthalide and its two homologues to 5- carboxyl- 1 -alkyltetrahydronaphthalene by 1,4 - hydride transfer and 3- propytphthalide to 4-carboxyl-1 -alkylindane by 1,3-hydride transfer in the p...The rearrangement of 3-butylphthalide and its two homologues to 5- carboxyl- 1 -alkyltetrahydronaphthalene by 1,4 - hydride transfer and 3- propytphthalide to 4-carboxyl-1 -alkylindane by 1,3-hydride transfer in the presence of AICI3 were observed and the possible mechanism was discussed.展开更多
The Claisen rearrangement is a [3,3]-sigmatropic rearrangement which is an important method for new C-C bond formation in organic synthesis. This reaction is a typical thermal reaction that requires a high temperature...The Claisen rearrangement is a [3,3]-sigmatropic rearrangement which is an important method for new C-C bond formation in organic synthesis. This reaction is a typical thermal reaction that requires a high temperature and long reaction time. In this paper, the acceleration effects of the iron (III) chloride (FeCl3) catalyst and microwave irradiation during the Claisen rearrangement reaction of allyloxyarene derivatives are reported. The FeCl3 catalyst was able to initiate the reaction at low temperature and induced the subsequent cyclization reaction. The moderation of excellent yields was obtained in a short reaction time. The formation of complex ferric-arenes under microwave irradiation conditions to efficiently absorb the microwaves was expected and confirmed.展开更多
基金The authors acknowledge financial support from the National Natural Science Foundation of China(grant nos.21625205 and 21772127).
文摘Organoselenium compounds,due to their high structural diversity,special function,and biological activities,have drawn attention in synthetic chemistry.Herein,a novel example of chiral N,N′-dioxide/cobalt(Ⅱ)complex catalyzed asymmetric[2,3]-sigmatropic rearrangement of allylic selenides withα-diazo pyrazoleamides is disclosed,which represents a highly efficient approach to optically active selenides bearing a quaternary C–Se stereocenter.Most of the reactions proceed with 0.5–2 mol%catalyst loading in an inert-free gas atmosphere,and a wealth of chiral selenides are obtained in up to 99% yield and 97%enantiomeric excess(ee).The control experiments demonstrate the high reactivity of allylic selenides,as well as the conspicuous superiority of chiral N,N′-dioxide ligand andα-diazo pyrazoleamide in[2,3]-sigmatropic rearrangement.The mechanism studies reveal that the key to asymmetric rearrangement of allylic selenium ylides is the transfer of chirality from the stable chiral selenium to the carbon of the product.A feasible catalytic cycle is proposed as well.
基金Project supported by the National Natural Science Foundation of China(Nos.20225205 and 20172002),State Key Laboratory of Elemento-Organic Chemistry of Nankai University and by Trans-Century Training Programme foundation for the Talents by Ministry of Edu
文摘The first investigation on catalytic asymmetric [2,3]-sigmatrop-ic rearrangement of sulfur ylides generated from carbenoids and allenic phenyl sulfide was carried out. Up to 55% ee value was obtained.
基金support from the Natural Science Foundation of Gansu Province(No.3ZS061-A25-019)the Scientific Research fund of Gansu Provincial Education Department(No.0601-25)
文摘Under mild conditions, conversion of a variety of ketoximes and aldoximes to their corresponding amides and nitriles proceeded in the presence of PEG-SO3H with high yields.
基金supported by the National Natural Science Foundation of China(QT group).
文摘The rearrangement reaction of 2-benzothiazolylthioacetyl hydrazide 1 with potassium hydroxide and carbon disulfide in ethanol to produce s-triazolo[3, 4-b]benzothiazole-3-thiol 3 was described. 3 also can be obtained from 2-benzothiazolylhydazine 2 and the two methods for getting 3 were compared. Mannich reaction of compounds 3 was reported too.
基金ACKNOWLEDGMENTS This work was supported by the Chinese Academy of Sciences, the Specialized Research Fund for the Doctoral Program of Higher Education, the National Basic Research Program of China （No.2007CB815204）, and the China Postdoctoral Science Foundation （No.20070420726 and No.20070410793）.
文摘The AIEt3-promoted tandem reductive rearrangement reactions of epoxides was studied at B3LYP/6- 31C（d,p） level. For the model compound α-hydroxy epoxides, two possible reaction pathways Ⅰ and Ⅱ were calculated. The main difference is the order of ethylene release and six- to five-member ring rearrangement. The ring contraction rearrangement in pathway Ⅰ is the first step and this step is the rate controlling step with a free energy barrier of 116.62 kJ/mol. For pathway Ⅱ, the ethylene release occurs first, and is followed by a six-member ring opening reaction which is the rate controlling step, and the barrier is 251.38 kJ/mol. The reason for such high barrier is that the ethylene release results in the following reaction being more difficult. The results show that pathway Ⅰ （C-C rearrangement and then ethylene release） is more favorable, which is consistent with experimental results.
基金PhD Special Research Foundation of Chinese Education Department (No. 20040422010)the Scientific Research Foundation of Yangzhou University
文摘Theoretical calculations of the [2,3]-sila-wittig rearrangement of isomers of [（allyloxy）silyl]lithium （C3H5O）HzSiLi have been performed in the gas phase and THF solvent using the G3MP2B3 method. Seven isomers of silylenoid （C3H5O）H2SiLi, 1-7, are found. The [2,3]-silawittig rearrangement paths are followed using two isomers, 2 and 4, to yield the transition states as well as the products. In the transition state, the silicon center functions as a nucleophile and the aUyl as an electrophile. The interaction between the silicon and allylic sites leads to the formation of SiC（3） bond and the break of O-C（1） bond. Finally, the （allylsilyl）oxylithium （C3H5）H2SiOLi is obtained. The rearrangement paths are confirmed by the intrinsic reaction coordinate （IRC） calculations. The rearrangement mechanisms of reactions of 2 and 4 are similar, and the latter reaction is more favored in the gas phase and THF solvent. Also, the solvent effects are analyzed in this work.
文摘By the Grignard reaction of 1,1-di-deutero-1-bromobutane with phthalaldehydic acid 1',1'-di-deutero-3-n-butyl phthalide was obtained, which underwent a rearrangement reaction using AlCl3 as catalyst in CS2 to give 1-methyl-5-carboxy-3,4-di-deutero-tetrahydronaphthalene. The mechanism was proposed to be a series of consecutive 1,2- hydride transfers rather than a direct 1,4-hydride transfer.
文摘The addition of platinum over the B2O3/TiO2-ZrO2 remarkably enhanced its catalytic stability in the vapor phase Beckmann rearrangement of cyclohexanone oxime under the carder gas of H2. The content of coke deposited on catalyst surface was decreased from 1.92% over the B2O3/TiO2-ZrO2 to 1.14% over the platinum promoted B2O3/TiO2-ZrO2 after reaction of six hours. This result indicates that the platinum added on the B2O3/TiO2-ZrO2 catalyst plays an important role in reducing the coke formation on the catalyst surface.
文摘The configuration of the hydroxy acid 2, a product from base-catalyzed autoxidation of 3α,5-cyclo-5α-cholestane-6-one,was established on the basis of NMR techniques and the mechanism of the formation of 2 was discussed.
文摘The rearrangement of 3-butylphthalide and its two homologues to 5- carboxyl- 1 -alkyltetrahydronaphthalene by 1,4 - hydride transfer and 3- propytphthalide to 4-carboxyl-1 -alkylindane by 1,3-hydride transfer in the presence of AICI3 were observed and the possible mechanism was discussed.
文摘The Claisen rearrangement is a [3,3]-sigmatropic rearrangement which is an important method for new C-C bond formation in organic synthesis. This reaction is a typical thermal reaction that requires a high temperature and long reaction time. In this paper, the acceleration effects of the iron (III) chloride (FeCl3) catalyst and microwave irradiation during the Claisen rearrangement reaction of allyloxyarene derivatives are reported. The FeCl3 catalyst was able to initiate the reaction at low temperature and induced the subsequent cyclization reaction. The moderation of excellent yields was obtained in a short reaction time. The formation of complex ferric-arenes under microwave irradiation conditions to efficiently absorb the microwaves was expected and confirmed.
