Jun Zhang

Facile syntheses of N-heterocyclic carbene precursors through Cu(II)- or Ag(I)-catalyzed amination of N-alkynyl formamidines

Co-reporter:Caiyun Zhang;Fan Zhang;Shichang Lv;Min Shi

New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 5) pp:1889-1892

Publication Date(Web):2017/02/28

DOI:10.1039/C6NJ03276A

We have developed a facile method for the synthesis of novel five- and six-membered cyclic formamidinium salts bearing an unsaturated backbone through Cu(II)- or Ag(I)-catalyzed amination of N-alkynyl formamidines. Cu(II)- or Ag(I)-promoted cyclization in a stoichiometric mode was also investigated, and it could offer some desirable cyclic formamidinium salts, which cannot be prepared through a catalytic reaction mode. Two rhodium(I) complexes were prepared through the treatment of [Rh(cod)Cl]2 with the free carbenes obtained in situ by the deprotonation of the corresponding resulting formamidinium salts.

Highly active chromium-based selective ethylene tri-/tetramerization catalysts supported by N,N-diphospholylamines

Co-reporter:Xiaoyu Ji, Liubing Song, Chengye Zhang, Jiajun Jiao, Jun Zhang

Inorganica Chimica Acta 2017 Volume 466(Volume 466) pp:

Publication Date(Web):1 September 2017

DOI:10.1016/j.ica.2017.05.042

We have developed novel Cr(III) catalysts supported by asymmetic N,N-diphospholylamine ligands bearing a phenoxaphosphine group. Upon activation with MMAO-3A, the Cr(III) catalysts supported by the PNP ligands are highly active for ethylene tri-/tetramerization with considerable selectivity. The ligand substitution and oligomerization conditions are found to be essential to achieve high activity and controllable selectivity. The catalytic system with asymmetric diphospholylamine ligands exhibited higher activity than that supported by symmetric ligands. Asymmetric diphospholylamine ligand with a N-cyclohexyl group achieved the highest activity of 282.2 kg/(g Cr/h) with a high total selectivity of 83.2% toward valuable 1-hexene (28.7%) and 1-octent (54.5%) at 35 bar under 80 °C.Cr(III) catalysts supported by asymmetic N,N-diphospholylamine ligands bearing a phenoxaphosphine group are highly active for ethylene tri-/tetramerization with considerable selectivity upon activation with MMAO-3A. Asymmetric PNP ligand with a N-cyclohexyl group achieved the highest activity of 282.2 kg/(g Cr/h) with a high total selectivity of 83.2% toward valuable 1-hexene (28.7%) and 1-octene (54.5%) at 35 bar under 80 °C.Download high-res image (69KB)Download full-size image

Ethylene tri-/tetramerization catalysts supported by diphosphinothiophene ligands

Co-reporter:Chengye Zhang;Liubing Song;Hongfei Wu;Xiaoyu Ji;Jiajun Jiao

Dalton Transactions 2017 vol. 46(Issue 26) pp:8399-8404

Publication Date(Web):2017/07/04

DOI:10.1039/C7DT01060E

Cr(III) catalysts supported by a series of diphosphinothiophene ligands have been developed, all of which, upon activation with MMAO-3A, are active for ethylene tri-/tetramerization. The effect of ligand substitution on the catalytic performance has been examined. The Cr precatalyst supported by the diphosphinothiophene ligand containing one trimethylsilyl group at the C2 position achieved a high activity of up to 686 kg (g Cr h−1)−1 with a total selectivity of up to 69% toward 1-hexene (29.5%) and 1-octene (39.5%). Two representative Cr complexes bearing the diphosphinothiophene ligand were synthesized and structurally characterized by single-crystal X-ray diffraction. Comparison of the coordination structure data of the two Cr complexes with those of an analogous diphosphine Cr complex reveals a direct correlation between the bond length of two adjacent bridging carbon atoms and catalytic activity: a shorter bond length and hence smaller ligand bite angle lead to higher catalytic activity. These diphosphinothiophene ligands featuring a fine-tuned backbone provide a model for the precise understanding of the impact of ligand variations on the catalytic performance.

Catalytic domino amination and oxidative coupling of gold acetylides and isolation of key vinylene digold intermediates as a new class of ditopic N-heterocyclic carbene complexes

Co-reporter:Haifeng Chen;Jiwei Wang;Zejun Hu;Sheng Xu;Min Shi

Chemical Communications 2017 vol. 53(Issue 78) pp:10835-10838

Publication Date(Web):2017/09/28

DOI:10.1039/C7CC06069F

A catalytic domino amination and oxidative coupling of in situ prepared gold acetylides has been developed for the synthesis of abnormal NHC (aNHC) gold complexes, and key vinylene digold intermediates are isolated and structurally characterized.

Heteroscorpionate bis-pyrazolyl ligands in Cr(III)-catalyzed ethylene oligomerization

Co-reporter:Mingfang Zheng, Hongfei Wu, Xuejun Zhang, Jun Zhang

Journal of Organometallic Chemistry 2016 Volume 817() pp:21-25

Publication Date(Web):15 August 2016

DOI:10.1016/j.jorganchem.2016.04.033

•New Cr(III) catalysts supported by the bis-pyrazoyl ligands with a third heteroaryl group.•The Cr(III) catalysts for the selective ethylene trimerization and tetramerization.•Formation of An acetoxychromium(III) chloride from carboxyl-containing ligand through the HCl elimination.We have investigated Cr(III) catalysts supported by the bis-pyrazoyl ligands containing a range of appendices from heteroaryl groups, such as quinolinyl, furanyl, and thiopheneyl, to hydroxy-containing groups such as carboxyl and hydroxyl. These catalysts, upon activation with MAO, are active for ethylene oligomerization. The Cr precatalyst supported by the bis-pyrazolyl ligand with thiopheneyl achieved a activity of 29.8 kg/(g Cr/h) with a total selectivity of 58.5% toward 1-hexene and 1-octene. The complexation reaction of carboxyl-containing ligand with Cr(THF)3Cl3 gave an acetoxychromium(III) chloride through the HCl elimination.

Facile Syntheses of N-Heterocyclic Carbene Precursors through I2- or NIS-Promoted Amidiniumation of N-Alkenyl Formamidines

Co-reporter:Jing Li;Jiajun Jiao;Caiyun Zhang;Dr. Min Shi;Dr. Jun Zhang

Chemistry – An Asian Journal 2016 Volume 11( Issue 9) pp:1361-1365

Publication Date(Web):

DOI:10.1002/asia.201600182

Abstract

We have developed I₂- or N-iodosuccinimide (NIS)-mediated amidiniumation of N-alkenyl formamidines for the syntheses of cyclic formamidinium salts, some of which could be directly used as N-heterocyclic carbene (NHC) precursors. Treatment of iodine-containing formamidinium salts with Al₂O₃ led to the formation of cyclic formamidinium salts with an unsaturated backbone. A rhodium(I) complex ligated by a representative NHC was prepared by the reaction of [Rh(cod)Cl]₂ (cod=1,5-cyclooctadiene) with the free carbene obtained in situ from deprotonation of the corresponding formamidinium salts. The NHCs prepared in situ can also react with S₈ to afford the corresponding thiones.

Copper, Silver and Sodium Salt-Mediated Quaternization by Arylation: Syntheses of N-Heterocyclic Carbene Precursors and 6-H-Phenanthridine Derivatives

Co-reporter:Wenqi Shen;Jing Li;Caiyun Zhang;Dr. Min Shi;Dr. Jun Zhang

Chemistry – An Asian Journal 2016 Volume 11( Issue 13) pp:1883-1886

Publication Date(Web):

DOI:10.1002/asia.201600563

Abstract

We have developed a Cu^II-, Ag^I-, and NaOTf-mediated intramolecular quaternization by arylation reactions to synthesize a variety of N-heterocyclic carbene (NHC) precursors with a benzene-fused backbone. The methodology also provides a convenient alternative route for the synthesis of 6-H-phenanthridine derivatives. A novel silver–NHC complex was prepared by treatment of Ag₂O with the free carbene, which was in situ prepared from the deprotonation of a representative quinazolinonium salt.

Highly active chromium-based selective ethylene tri-/tetramerization catalysts supported by PNPO phosphazane ligands

Co-reporter:Yusheng Zhou, Hongfei Wu, Sheng Xu, Xuejun Zhang, Min Shi and Jun Zhang

Dalton Transactions 2015 vol. 44(Issue 20) pp:9545-9550

Publication Date(Web):28 Apr 2015

DOI:10.1039/C5DT00801H

Novel Cr(III) catalysts supported by PNPO phosphazane ligands of the type Ph2PN(R)P(Ph)OAr have been prepared, all of which, upon activation with MMAO-3A, are highly active in ethylene tri-/tetramerization with considerable selectivity. The effect of ligand substitution on the catalytic performance has been examined. The Cr precatalyst supported by the PNPO phosphazane ligand with an N-cyclohexyl achieved high activity of 316.7 kg (g Cr h−1)−1 and a high total selectivity of 85.1% towards valuable 1-hexene (45.7%) and 1-octene (39.4%) using chlorobenzene as the solvent at 35 bar and 40 °C. In methylcyclohexane, the precatalyst supported by [Ph2PN(iPr)P(Ph)OPh] exhibited a higher 1-octene selectivity (54.0%) with a considerable activity of 73.3 kg (g Cr h−1)−1 at 35 bar and 40 °C. With the fine-tuned ligand backbone, such a PNPO phosphazane-based catalyst system provides a mode for precise understanding of the impact of ligand variations on catalytic performance.

Intramolecular aminochalcogenation and diamination of alkenes employing N-iodosuccinimide

Co-reporter:Jun Zhang, Xuejun Zhang, Weijie Wu, Gengtao Zhang, Sheng Xu, Min Shi

Tetrahedron Letters 2015 Volume 56(Issue 12) pp:1505-1509

Publication Date(Web):18 March 2015

DOI:10.1016/j.tetlet.2015.01.154

A NIS-mediated intramolecular diamination and aminosulfuration of alkenes with N-alkyl or N-aryl thioureas is reported. A chiral cyclic thiourea was also synthesized by the methodology. The protocol is also proven to be efficient in the intramolecular diamination and/or aminooxygenation of alkenes with N-alkyl or N-aryl ureas and ones with N-carbamate sulfamides. The resulting bicyclic thiourea could be further transformed into bicyclic guanidine.A NIS-mediated intramolecular diamination and aminosulfuration of alkenes with N-alkyl or N-aryl thioureas have been developed, which is also proven to be efficient in the intramolecular diamination and/or aminooxygenation of alkenes with N-alkyl or N-aryl ureas and ones with N-carbamate sulfamides.

Silver-Catalyzed Amidiniumation of Alkynes: Isolation of a Silver Intermediate, Synthesis of Enamine Amido Carbene Precursors, and an Unprecedented Umpolung of Propiolamide

Co-reporter:Shichang Lv;Jiwei Wang;Caiyun Zhang;Dr. Sheng Xu;Dr. Min Shi;Dr. Jun Zhang

Angewandte Chemie International Edition 2015 Volume 54( Issue 49) pp:14941-14946

Publication Date(Web):

DOI:10.1002/anie.201508221

Abstract

A silver-catalyzed amidiniumation of N-propiolic formamidines for the synthesis of novel enamine amido carbene precursors is reported. Isolation of a first silver intermediate in silver-catalyzed amidiniumation of alkynes and other organogold intermediates supports our proposed mechanisms. Several control experiments reveal the unexpected effects of both HOTf and substrate substituents on the choice of either a π or σ,π silver activation mode and the cyclization fashion. Bis(hydroxyimidazol)ium salts were obtained through an unprecedented umpolung of propiolamides. The byproduct Ag₂O as either an oxidant or silver source promotes the syntheses of N-heterocyclic carbene (NHC) precursors or Ag/NHC complexes.

NIS/PhI(OAc)2-Mediated Diamination/Oxidation of N-Alkenyl Formamidines: Facile Synthesis of Fused Tricyclic Ureas

Co-reporter:Dr. Jun Zhang;Weijie Wu;Xuejun Zhang;Gengtao Zhang;Dr. Sheng Xu;Dr. Min Shi

Chemistry – An Asian Journal 2015 Volume 10( Issue 3) pp:544-547

Publication Date(Web):

DOI:10.1002/asia.201403281

Abstract

Facile synthesis of bicyclic ureas by NIS/PhI(OAc)₂-mediated diamination/oxidation of N-alkenyl formamidines is reported. Bulky aromatic groups such as 2,6-diisopropylphenyl and mesityl and alkyl groups were tolerated towards the process. Several control experiments have been performed, and the reaction outcomes indicate that the oxidation process is probably concerted with the diamination cyclization, and succinimide generated from NIS-mediated aminoamidiniumation step promoted the PhI(OAc)₂-mediated oxidation step. The new methodology provides an efficient method for the synthesis of fused tricyclic ureas.

Silver-Catalyzed Amidiniumation of Alkynes: Isolation of a Silver Intermediate, Synthesis of Enamine Amido Carbene Precursors, and an Unprecedented Umpolung of Propiolamide

Co-reporter:Shichang Lv;Jiwei Wang;Caiyun Zhang;Dr. Sheng Xu;Dr. Min Shi;Dr. Jun Zhang

Angewandte Chemie 2015 Volume 127( Issue 49) pp:15154-15159

Publication Date(Web):

DOI:10.1002/ange.201508221

Abstract

A silver-catalyzed amidiniumation of N-propiolic formamidines for the synthesis of novel enamine amido carbene precursors is reported. Isolation of a first silver intermediate in silver-catalyzed amidiniumation of alkynes and other organogold intermediates supports our proposed mechanisms. Several control experiments reveal the unexpected effects of both HOTf and substrate substituents on the choice of either a π or σ,π silver activation mode and the cyclization fashion. Bis(hydroxyimidazol)ium salts were obtained through an unprecedented umpolung of propiolamides. The byproduct Ag₂O as either an oxidant or silver source promotes the syntheses of N-heterocyclic carbene (NHC) precursors or Ag/NHC complexes.

Metal-free aminoamidiniumation employing N-iodosuccinimide: facile syntheses of bicyclic imidazolidiniums and cyclic vicinal diamines

Co-reporter:Jun Zhang, Gengtao Zhang, Weijie Wu, Xuejun Zhang and Min Shi

Chemical Communications 2014 vol. 50(Issue 95) pp:15052-15054

Publication Date(Web):09 Oct 2014

DOI:10.1039/C4CC07082H

NIS-mediated aminoamidiniumation has been developed for the syntheses of bicyclic imidazolidinium salts, which could be readily converted into cyclic vicinal diamines.

Switchable Ethylene Tri-/Tetramerization with High Activity: Subtle Effect Presented by Backbone-Substituent of Carbon-Bridged Diphosphine Ligands

Co-reporter:Jun Zhang, Xiao Wang, Xuejun Zhang, Weijie Wu, Gengtao Zhang, Sheng Xu, and Min Shi

ACS Catalysis 2013 Volume 3(Issue 10) pp:2311

Publication Date(Web):September 18, 2013

DOI:10.1021/cs400651h

The effect of backbone-substituent of carbon-bridged diphosphine ligands of the types {Ph2PCH(R)CH2PPh2} and {Ph2PC(R)═CHPPh2} on the catalyst performance in ethylene oligomerization has been explored. Cr complex bearing a methyl-substituted diphosphine ligand with saturated linker exhibited the highest selectivity of 64.7% toward 1-octene. Cr complex bearing a tert-butyl-substituted diphosphine ligand with unsaturated linker showed a high activity of 4238 kg/(g Cr/h) at 40 bar and 40 °C and achieved a high total selectivity of 79.1% toward valuable 1-hexene and 1-octene. The 1-hexene selectivity could be improved up to 55.2% (19.4% 1-octene) at 20 bar and 80 °C. Some of the new complexes are even more active than the well-known most efficient ethylene tri/tetramerization catalyst systems.Keywords: backbone-substituent; chromium(III) catalysts; diphosphine ligand; ethylene tetramerization; ethylene trimerization

Ruthenium-catalyzed olefin metathesis accelerated by the steric effect of the backbone substituent in cyclic (alkyl)(amino) carbenes

Co-reporter:Jun Zhang, Shangfei Song, Xiao Wang, Jiajun Jiao and Min Shi

Chemical Communications 2013 vol. 49(Issue 82) pp:9491-9493

Publication Date(Web):14 Aug 2013

DOI:10.1039/C3CC45823G

Three ruthenium complexes bearing backbone-monosubstituted CAACs were prepared and displayed dramatic improvement in catalytic efficiency not only in RCM reaction but also in the ethenolysis of methyl oleate, compared to those bearing backbone-disubstituted CAACs.

Synthesis of Various Saturated and Unsaturated N-Heterocyclic Carbene Precursors by Triflic Anhydride Mediated Intramolecular Cyclization

Co-reporter:Dr. Jun Zhang;Jun Fu;Xiaolong Su;Xiao Wang;Shangfei Song;Dr. Min Shi

Chemistry – An Asian Journal 2013 Volume 8( Issue 3) pp:552-555

Publication Date(Web):

DOI:10.1002/asia.201201082

Abnormal oxazol-4-ylidene and thiazol-4-ylidene rhodium complexes: synthesis, structure, and properties

Co-reporter:Jun Zhang, Jun Fu, Xiaolong Su, Xinke Qin, Meixin Zhao and Min Shi

Chemical Communications 2012 vol. 48(Issue 77) pp:9625-9627

Publication Date(Web):10 Aug 2012

DOI:10.1039/C2CC35020C

A series of new 2,3,5-triaryl-substituted oxazolium and thiazolium salts are readily prepared by a Tf2O-mediated intramolecular cyclisation and their use as precursors for the synthesis of novel oxazol-4-ylidene and thiazol-4-ylidene rhodium complexes has been developed.

Tailor-made synthesis of various backbone-substituted imidazolinium salts by triflic anhydride mediated intramolecular cyclisation

Co-reporter:Jun Zhang, Xiaolong Su, Jun Fu, Xinke Qin, Meixin Zhao and Min Shi

Chemical Communications 2012 vol. 48(Issue 73) pp:9192-9194

Publication Date(Web):26 Jul 2012

DOI:10.1039/C2CC34952C

We have found a Tf2O-mediated intramolecular cyclization reaction and have revealed an intriguing stereoselectivity and a regioselectivity during the preparation of intermediate alcohols, which allow for the tailor-made synthesis of various backbone-substituted imidazolinium salts, and structurally specific syn-4,5-disubstituted imidazolinium salts.

Fine-Tunable 3,4-Dihydroquinazol-2-ylidene Carbenes: Synthesis, Rhodium(I) Complexes, and Reactivity

Co-reporter:Jun Zhang, Xinke Qin, Jun Fu, Xiao Wang, Xiaolong Su, Fangle Hu, Jiajun Jiao, and Min Shi

Organometallics 2012 Volume 31(Issue 23) pp:8275-8282

Publication Date(Web):November 5, 2012

DOI:10.1021/om300887y

The design and synthesis of various new six-membered cyclic formamidinium salts with a 3,4-dihydroquinazoline core have been reported in this paper. Our synthetic strategy allows access to a kind of tailor-made 3,4-dihydroquinazolinium salts bearing different substituent combinations. A series of novel 3,4-dihydroquinazolin-2-ylidene-based rhodium(I) complexes were prepared by the reaction of [Rh(cod)Cl]2 with the free carbene obtained in situ from the deprotonation of the corresponding 3,4-dihydroquinazolinium salts with KN(SiMe3)2. The NHCs prepared in situ can also react with S8 or CS2 to afford the corresponding thiones or NHC–CS2 adducts, respectively. The rhodium(I) complexes were transformed to the corresponding dicarbonyl complexes, and the ν(CO) values of the corresponding dicarbonyl Rh complexes indicate the 3,4-dihydroquinazol-2-ylidenes are stronger electron donors than normal five-membered NHCs. The Rh complexes are highly active in the arylation of carbonyl compounds, and the 3,4-dihydroquinazolin-2-ylidenes prepared in situ upon deprotonation are powerful in palladium-catalyzed Suzuki cross-coupling reactions at room temperature with a ppm scale catalyst loading with TONs of up to 425 000.

A facile preparation of backbone-substituted, functionalized and chiral imidazolinium salts

Co-reporter:Jun Zhang, Xiaolong Su, Jun Fu and Min Shi

Chemical Communications 2011 vol. 47(Issue 46) pp:12541-12543

Publication Date(Web):24 Oct 2011

DOI:10.1039/C1CC15609H

A versatile and modular method for the preparation of various backbone-substituted, functionalized and chiral imidazolinium salts from the reaction of formamidines with alkene oxides has been described, providing a more straightforward access to substituted imidazolinium salts than the previously reported methods.

A facile preparation of backbone-substituted, functionalized and chiral imidazolinium salts

Co-reporter:Jun Zhang, Xiaolong Su, Jun Fu and Min Shi

Chemical Communications 2011 - vol. 47(Issue 46) pp:NaN12543-12543

Publication Date(Web):2011/10/24

DOI:10.1039/C1CC15609H

A versatile and modular method for the preparation of various backbone-substituted, functionalized and chiral imidazolinium salts from the reaction of formamidines with alkene oxides has been described, providing a more straightforward access to substituted imidazolinium salts than the previously reported methods.

Highly active chromium-based selective ethylene tri-/tetramerization catalysts supported by PNPO phosphazane ligands

Co-reporter:Yusheng Zhou, Hongfei Wu, Sheng Xu, Xuejun Zhang, Min Shi and Jun Zhang

Dalton Transactions 2015 - vol. 44(Issue 20) pp:NaN9550-9550

Publication Date(Web):2015/04/28

DOI:10.1039/C5DT00801H

Novel Cr(III) catalysts supported by PNPO phosphazane ligands of the type Ph2PN(R)P(Ph)OAr have been prepared, all of which, upon activation with MMAO-3A, are highly active in ethylene tri-/tetramerization with considerable selectivity. The effect of ligand substitution on the catalytic performance has been examined. The Cr precatalyst supported by the PNPO phosphazane ligand with an N-cyclohexyl achieved high activity of 316.7 kg (g Cr h−1)−1 and a high total selectivity of 85.1% towards valuable 1-hexene (45.7%) and 1-octene (39.4%) using chlorobenzene as the solvent at 35 bar and 40 °C. In methylcyclohexane, the precatalyst supported by [Ph2PN(iPr)P(Ph)OPh] exhibited a higher 1-octene selectivity (54.0%) with a considerable activity of 73.3 kg (g Cr h−1)−1 at 35 bar and 40 °C. With the fine-tuned ligand backbone, such a PNPO phosphazane-based catalyst system provides a mode for precise understanding of the impact of ligand variations on catalytic performance.

Ethylene tri-/tetramerization catalysts supported by diphosphinothiophene ligands

Co-reporter:Chengye Zhang, Liubing Song, Hongfei Wu, Xiaoyu Ji, Jiajun Jiao and Jun Zhang

Dalton Transactions 2017 - vol. 46(Issue 26) pp:NaN8404-8404

Publication Date(Web):2017/05/31

DOI:10.1039/C7DT01060E

Cr(III) catalysts supported by a series of diphosphinothiophene ligands have been developed, all of which, upon activation with MMAO-3A, are active for ethylene tri-/tetramerization. The effect of ligand substitution on the catalytic performance has been examined. The Cr precatalyst supported by the diphosphinothiophene ligand containing one trimethylsilyl group at the C2 position achieved a high activity of up to 686 kg (g Cr h−1)−1 with a total selectivity of up to 69% toward 1-hexene (29.5%) and 1-octene (39.5%). Two representative Cr complexes bearing the diphosphinothiophene ligand were synthesized and structurally characterized by single-crystal X-ray diffraction. Comparison of the coordination structure data of the two Cr complexes with those of an analogous diphosphine Cr complex reveals a direct correlation between the bond length of two adjacent bridging carbon atoms and catalytic activity: a shorter bond length and hence smaller ligand bite angle lead to higher catalytic activity. These diphosphinothiophene ligands featuring a fine-tuned backbone provide a model for the precise understanding of the impact of ligand variations on the catalytic performance.

Tailor-made synthesis of various backbone-substituted imidazolinium salts by triflic anhydride mediated intramolecular cyclisation

Co-reporter:Jun Zhang, Xiaolong Su, Jun Fu, Xinke Qin, Meixin Zhao and Min Shi

Chemical Communications 2012 - vol. 48(Issue 73) pp:NaN9194-9194

Publication Date(Web):2012/07/26

DOI:10.1039/C2CC34952C

We have found a Tf2O-mediated intramolecular cyclization reaction and have revealed an intriguing stereoselectivity and a regioselectivity during the preparation of intermediate alcohols, which allow for the tailor-made synthesis of various backbone-substituted imidazolinium salts, and structurally specific syn-4,5-disubstituted imidazolinium salts.

Abnormal oxazol-4-ylidene and thiazol-4-ylidene rhodium complexes: synthesis, structure, and properties

Co-reporter:Jun Zhang, Jun Fu, Xiaolong Su, Xinke Qin, Meixin Zhao and Min Shi

Chemical Communications 2012 - vol. 48(Issue 77) pp:NaN9627-9627

Publication Date(Web):2012/08/10

DOI:10.1039/C2CC35020C

A series of new 2,3,5-triaryl-substituted oxazolium and thiazolium salts are readily prepared by a Tf2O-mediated intramolecular cyclisation and their use as precursors for the synthesis of novel oxazol-4-ylidene and thiazol-4-ylidene rhodium complexes has been developed.

Ruthenium-catalyzed olefin metathesis accelerated by the steric effect of the backbone substituent in cyclic (alkyl)(amino) carbenes

Co-reporter:Jun Zhang, Shangfei Song, Xiao Wang, Jiajun Jiao and Min Shi

Chemical Communications 2013 - vol. 49(Issue 82) pp:NaN9493-9493

Publication Date(Web):2013/08/14

DOI:10.1039/C3CC45823G

Three ruthenium complexes bearing backbone-monosubstituted CAACs were prepared and displayed dramatic improvement in catalytic efficiency not only in RCM reaction but also in the ethenolysis of methyl oleate, compared to those bearing backbone-disubstituted CAACs.

Metal-free aminoamidiniumation employing N-iodosuccinimide: facile syntheses of bicyclic imidazolidiniums and cyclic vicinal diamines

Co-reporter:Jun Zhang, Gengtao Zhang, Weijie Wu, Xuejun Zhang and Min Shi

Chemical Communications 2014 - vol. 50(Issue 95) pp:NaN15054-15054

Publication Date(Web):2014/10/09

DOI:10.1039/C4CC07082H

NIS-mediated aminoamidiniumation has been developed for the syntheses of bicyclic imidazolidinium salts, which could be readily converted into cyclic vicinal diamines.

Isolation and characterization of gem-diaurated species having two C–Au σ bonds in gold(I)-activated amidiniumation of alkynes

Co-reporter:Jiwei Wang, Shichang Lv, Haifeng Chen, Min Shi and Jun Zhang

Dalton Transactions 2016 - vol. 45(Issue 43) pp:NaN17094-17094

Publication Date(Web):2016/10/03

DOI:10.1039/C6DT03475F

We have investigated the ligand effect on the gold-activated intramolecular amidiniumation of formamidine having a terminal alkyne, and observed the transformation of vinyl gold species into a gem-digold intermediate comprising two C–Au σ bonds, which represents a new binding mode for gem-digold species in the gold-promoted transformation of alkynes.

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