Yu Zhao

Find an error

Name: NULL
Organization: National University of Singapore , Singapore
Department: Department of Chemistry
Title: NULL(PhD)

TOPICS

Co-reporter:Zi-Qiang Rong, Li-Cheng Yang, Song Liu, Zhaoyuan Yu, Ya-Nong Wang, Zher Yin Tan, Rui-Zhi Huang, Yu Lan, and Yu Zhao
Journal of the American Chemical Society November 1, 2017 Volume 139(Issue 43) pp:15304-15304
Publication Date(Web):October 17, 2017
DOI:10.1021/jacs.7b09161
The first enantioselective formal [5+4] cycloaddition is realized under palladium catalysis to deliver benzofuran-fused nine-membered rings. These medium-sized heterocycles and derivatives undergo unique rearrangements induced by transannular bond formation, resulting in the production of two classes of densely substituted polycyclic heterocycles in excellent efficiency and stereoselectivity.
Co-reporter:Jia-Yu Liao, Qijian Ni, and Yu Zhao
Organic Letters August 4, 2017 Volume 19(Issue 15) pp:
Publication Date(Web):July 14, 2017
DOI:10.1021/acs.orglett.7b01851
The first catalytic cascade reaction of activated isocyanides with para-quinone methide-aryl esters is presented. Catalyst-enabled divergent pathways have also been achieved to deliver skeletally diverse products. While Ag catalysis leads to an unprecedented highly diastereoselective synthesis of tricyclic ketals, a simple procedure employing Cu catalysis produces oxazole-containing triarylmethanes in high efficiency through an unexpected C–C bond cleavage.
Co-reporter:Jia-Yu Liao;Wei Jie Yap;Ji'En Wu;Ming Wah Wong
Chemical Communications 2017 vol. 53(Issue 65) pp:9067-9070
Publication Date(Web):2017/08/10
DOI:10.1039/C7CC03468G
We present herein a new mode of three-component reactions between isocyanoacetates, amines and 3-formylchromones. Both experimental and DFT studies revealed that this Ag-catalyzed unusual transformation is initiated by a facile aza-Michael addition instead of the conventional imine condensation. This catalytic method enables an efficient synthesis of polysubstituted pyrroles.
Co-reporter:Ching Si Lim;Thanh Truong Quach; Yu Zhao
Angewandte Chemie 2017 Volume 129(Issue 25) pp:7282-7286
Publication Date(Web):2017/06/12
DOI:10.1002/ange.201703704
AbstractWe report herein the highly enantioselective synthesis of 2-substituted tetrahydroquinolines through borrowing hydrogen, a process recognized for its environmentally benign and atom-economical nature. The use of an achiral iridacycle complex in combination with a chiral phosphoric acid as catalysts was the key to the development of this highly efficient and enantioselective transformation.
Co-reporter:Ching Si Lim;Thanh Truong Quach; Yu Zhao
Angewandte Chemie International Edition 2017 Volume 56(Issue 25) pp:7176-7180
Publication Date(Web):2017/06/12
DOI:10.1002/anie.201703704
AbstractWe report herein the highly enantioselective synthesis of 2-substituted tetrahydroquinolines through borrowing hydrogen, a process recognized for its environmentally benign and atom-economical nature. The use of an achiral iridacycle complex in combination with a chiral phosphoric acid as catalysts was the key to the development of this highly efficient and enantioselective transformation.
Co-reporter:Xiao-Jiao Peng;Yee Ann Ho;Zhi-Peng Wang;Pan-Lin Shao;Yun He
Organic Chemistry Frontiers 2017 vol. 4(Issue 1) pp:81-85
Publication Date(Web):2016/12/20
DOI:10.1039/C6QO00555A
The first enantioselective formal [3 + 2] cycloaddition of α-unsubstituted isocyanoacetates with protecting-group-free methyleneindolinones was developed. A variety of optically enriched 3,3′-pyrrolidinyl spirooxindoles were obtained in excellent yields, and diastereo- and enantioselectivities (up to 99% yield, >20 : 1 dr, 99% ee) with low catalyst loading under mild reaction conditions.
Co-reporter:Tang-Lin Liu;Ji’En Wu
Chemical Science (2010-Present) 2017 vol. 8(Issue 5) pp:3885-3890
Publication Date(Web):2017/05/03
DOI:10.1039/C7SC00483D
An unconventional cleavage of an unstrained carbon–carbon bond in allylic alcohols can be induced by the use of N-fluorobenzenesulfonimide (NFSI) under catalyst-free conditions. By using this simple procedure, a wide range of functionalized Z-fluoroalkenes can be accessed in high yield and selectivity from cyclic and acyclic allylic alcohols.
Co-reporter:Yuan Huang; Rui-Zhi Huang
Journal of the American Chemical Society 2016 Volume 138(Issue 20) pp:6571-6576
Publication Date(Web):May 3, 2016
DOI:10.1021/jacs.6b02372
We present here an unprecedented cobalt-catalyzed enantioselective vinylation of α-ketoesters, isatins, and imines to deliver a range of synthetically useful allylic alcohols and amines in high enantiopurity. This method employs commercially available and easy to handle catalysts and reagents and exhibits a high degree of practicality. The efficiency, selectivity, and operational simplicity of this catalytic system coupled with the substrate generality render this method a valuable tool in organic synthesis.
Co-reporter:Chao Ma, Yuan Huang, and Yu Zhao
ACS Catalysis 2016 Volume 6(Issue 10) pp:6408
Publication Date(Web):August 26, 2016
DOI:10.1021/acscatal.6b01845
Here, we present an unprecedented formal [3 + 2] cycloaddition of para-quinone methides with vinyl epoxides/cyclopropanes to deliver a wide range of spiro[4.5]decanes in high efficiency and stereoselectivity. The commercial availability of the catalysts and reagents, together with the convenient procedure, makes it an attractive method in asymmetric synthesis.Keywords: palladium catalysis; para-quinone methide; vinyl cyclopropane; vinyl epoxide; [3 + 2] cycloaddition
Co-reporter:Hui-Jie Pan, Teng Wei Ng and Yu Zhao  
Organic & Biomolecular Chemistry 2016 vol. 14(Issue 24) pp:5490-5493
Publication Date(Web):2015/11/03
DOI:10.1039/C5OB02119G
An iron-catalyzed transfer hydrogenation of N-aryl and N-alkyl imines using isopropanol as the hydrogen donor is reported for the first time. A combination of two iron complexes serving different roles is the key for the success of this catalytic system. As a result, an environmentally friendly and precious metal-free transfer hydrogenation of imines has been developed. The use of a suitable co-catalyst as an activator not only led to efficient transfer hydrogenation, but also showed potential in enantioselective transformation.
Co-reporter:Zi-Qiang Rong;Min Wang;Chi Hao Eugene Chow ; Yu Zhao
Chemistry - A European Journal 2016 Volume 22( Issue 28) pp:9483-9487
Publication Date(Web):
DOI:10.1002/chem.201601626

Abstract

Highly efficient and diastereodivergent aza-Diels–Alder reactions have been developed to access either diastereomeric series of benzofuran-fused δ-lactams and dihydropyridines in nearly perfect stereoselectivity (d.r. >20:1, >99 % ee for all examples). The complementarity of N-heterocyclic carbene and chiral amine as the catalyst was demonstrated for the first time, together with an excellent level of catalytic efficiency (1 mol % loading).

Co-reporter:Zi-Qiang Rong;Min Wang;Chi Hao Eugene Chow ; Yu Zhao
Chemistry - A European Journal 2016 Volume 22( Issue 28) pp:
Publication Date(Web):
DOI:10.1002/chem.201602587
Co-reporter:Jia-Yu Liao; Pan-Lin Shao
Journal of the American Chemical Society 2015 Volume 137(Issue 2) pp:628-631
Publication Date(Web):January 2, 2015
DOI:10.1021/ja511895q
The cyclization of allenoates with activated isocyanides was reported for the first time. While Ag catalysis led to an unprecedented enantioselective synthesis of 3H pyrroles, a simple procedure using PPh3 produced a wide range of polysubstituted 1H pyrroles with high efficiency.
Co-reporter:Zi-Qiang Rong; Yao Zhang; Raymond Hong Bing Chua; Hui-Jie Pan
Journal of the American Chemical Society 2015 Volume 137(Issue 15) pp:4944-4947
Publication Date(Web):April 2, 2015
DOI:10.1021/jacs.5b02212
The first dynamic kinetic asymmetric amination of alcohols via borrowing hydrogen methodology is presented. Under the cooperative catalysis by an iridium complex and a chiral phosphoric acid, α-branched alcohols that exist as a mixture of four isomers undergo racemization by two orthogonal mechanisms and are converted to diastereo- and enantiopure amines bearing adjacent stereocenters. The preparation of diastereo- and enantiopure 1,2-amino alcohols is also realized using this catalytic system.
Co-reporter:Sui-Boon Derek Sim, Min Wang, and Yu Zhao
ACS Catalysis 2015 Volume 5(Issue 6) pp:3609
Publication Date(Web):May 4, 2015
DOI:10.1021/acscatal.5b00583
An efficient and enantioselective α-hydroxylation of acyclic as well as cyclic ketones using molecular oxygen has been developed. This simple catalytic procedure uses a readily available phase-transfer catalyst and produces a wide range of valuable tertiary α-hydroxy ketones in good to excellent enantiopurity.Keywords: cinchona alkaloid; enantioselectivity; hydroxylation; oxygen; phase transfer catalysis; α-hydroxy ketone
Co-reporter:Hui-Jie Pan, Teng Wei Ng and Yu Zhao  
Chemical Communications 2015 vol. 51(Issue 59) pp:11907-11910
Publication Date(Web):17 Jun 2015
DOI:10.1039/C5CC03399C
An efficient Lewis acid-assisted, iron-catalyzed amination of alcohols using borrowing hydrogen methodology was developed. In particular, silver fluoride was identified to be a highly effective additive to overcome the low efficiency in the amination of secondary alcohols catalyzed by Knölker's complex.
Co-reporter:Yuan Huang;Chao Ma;Yi Xin Lee;Rui-Zhi Huang ; Yu Zhao
Angewandte Chemie International Edition 2015 Volume 54( Issue 46) pp:13696-13700
Publication Date(Web):
DOI:10.1002/anie.201506003

Abstract

The allylation of heterobicyclic alkenes is presented for the first time. By using an inexpensive cobalt salt as the catalyst and easy-to-handle potassium allyltrifluoroborate as the reagent, an unprecedented formal hydroallylation of the bicyclic alkenes is realized in high efficiency. When a chiral cobalt/bis(phosphine) complex is used instead, the alternative ring-opening products can be obtained in high yield and excellent enantioselectivity.

Co-reporter:Yuan Huang;Chao Ma;Yi Xin Lee;Rui-Zhi Huang ; Yu Zhao
Angewandte Chemie 2015 Volume 127( Issue 46) pp:13900-13904
Publication Date(Web):
DOI:10.1002/ange.201506003

Abstract

The allylation of heterobicyclic alkenes is presented for the first time. By using an inexpensive cobalt salt as the catalyst and easy-to-handle potassium allyltrifluoroborate as the reagent, an unprecedented formal hydroallylation of the bicyclic alkenes is realized in high efficiency. When a chiral cobalt/bis(phosphine) complex is used instead, the alternative ring-opening products can be obtained in high yield and excellent enantioselectivity.

Co-reporter:Min Wang, Zi-Qiang Rong and Yu Zhao  
Chemical Communications 2014 vol. 50(Issue 97) pp:15309-15312
Publication Date(Web):16 Oct 2014
DOI:10.1039/C4CC07788A
NHC-catalyzed divergent annulation of enals with heterocyclic enones was developed to produce benzofuran/indole-containing ε-lactones or spiro-heterocycles in a highly diastereo- and enantioselective fashion. The chemo-selectivity controlled by the chiral catalyst backbone is particularly noteworthy.
Co-reporter:Zi-Qiang Rong, Hui-Jie Pan, Hai-Long Yan, and Yu Zhao
Organic Letters 2014 Volume 16(Issue 1) pp:208-211
Publication Date(Web):December 9, 2013
DOI:10.1021/ol4032045
Quinine-derived urea has been identified as a highly efficient organocatalyst for the enantioselective oxidation of 1,2-diols using bromination reagents as the oxidant. This simple procedure utilizes readily available reagents and operates at ambient temperature to yield a wide range of α-hydroxy ketones in good yield (up to 94%) and excellent enantioselectivity (up to 95% ee).
Co-reporter:Dr. Shenci Lu;Si Bei Poh ; Yu Zhao
Angewandte Chemie 2014 Volume 126( Issue 41) pp:11221-11225
Publication Date(Web):
DOI:10.1002/ange.201406192

Abstract

We present here a highly efficient NHC-catalyzed kinetic resolution of a wide range of 1,1′-biaryl-2,2′-diols and amino alcohols to provide them in uniformly ≥99 % ee. This represents the first highly enantioselective catalytic acylation of axially chiral alcohols. The aldehyde backbone that is incorporated into the chiral acyl azolium intermediate was found to have a significant effect on the enantioselectivity of the process.

Co-reporter:Dr. Yao Zhang;Ching-Si Lim;Derek Sui Boon Sim;Hui-Jie Pan ; Yu Zhao
Angewandte Chemie International Edition 2014 Volume 53( Issue 5) pp:1399-1403
Publication Date(Web):
DOI:10.1002/anie.201307789

Abstract

The catalytic asymmetric reduction of ketimines has been explored extensively for the synthesis of chiral amines, with reductants ranging from Hantzsch esters, silanes, and formic acid to H2 gas. Alternatively, the amination of alcohols by the use of borrowing hydrogen methodology has proven a highly atom economical and green method for the production of amines without an external reductant, as the alcohol substrate serves as the H2 donor. A catalytic enantioselective variant of this process for the synthesis of chiral amines, however, was not known. We have examined various transition-metal complexes supported by chiral ligands known for asymmetric hydrogenation reactions, in combination with chiral Brønsted acids, which proved essential for the formation of the imine intermediate and the transfer-hydrogenation step. Our studies led to an asymmetric amination of alcohols to provide access to a wide range of chiral amines with good to excellent enantioselectivity.

Co-reporter:Dr. Pan-Lin Shao;Jia-Yu Liao;Yee Ann Ho ; Yu Zhao
Angewandte Chemie International Edition 2014 Volume 53( Issue 21) pp:5435-5439
Publication Date(Web):
DOI:10.1002/anie.201402788

Abstract

Presented herein is a new complexity-generating method in which both functionalities of α-imino esters undergo stereoselective cyclization with isocyanoacetates to produce directly linked oxazole-imidazolines, which can be transformed into highly functionalized α,β-diamino esters and imidazolinium salts in high diastereo- and enantiopurity.

Co-reporter:Dr. Yao Zhang;Ching-Si Lim;Derek Sui Boon Sim;Hui-Jie Pan ; Yu Zhao
Angewandte Chemie 2014 Volume 126( Issue 5) pp:1423-1427
Publication Date(Web):
DOI:10.1002/ange.201307789

Abstract

The catalytic asymmetric reduction of ketimines has been explored extensively for the synthesis of chiral amines, with reductants ranging from Hantzsch esters, silanes, and formic acid to H2 gas. Alternatively, the amination of alcohols by the use of borrowing hydrogen methodology has proven a highly atom economical and green method for the production of amines without an external reductant, as the alcohol substrate serves as the H2 donor. A catalytic enantioselective variant of this process for the synthesis of chiral amines, however, was not known. We have examined various transition-metal complexes supported by chiral ligands known for asymmetric hydrogenation reactions, in combination with chiral Brønsted acids, which proved essential for the formation of the imine intermediate and the transfer-hydrogenation step. Our studies led to an asymmetric amination of alcohols to provide access to a wide range of chiral amines with good to excellent enantioselectivity.

Co-reporter:Dr. Pan-Lin Shao;Jia-Yu Liao;Yee Ann Ho ; Yu Zhao
Angewandte Chemie 2014 Volume 126( Issue 21) pp:5539-5543
Publication Date(Web):
DOI:10.1002/ange.201402788

Abstract

Presented herein is a new complexity-generating method in which both functionalities of α-imino esters undergo stereoselective cyclization with isocyanoacetates to produce directly linked oxazole-imidazolines, which can be transformed into highly functionalized α,β-diamino esters and imidazolinium salts in high diastereo- and enantiopurity.

Co-reporter:Dr. Shenci Lu;Si Bei Poh ; Yu Zhao
Angewandte Chemie International Edition 2014 Volume 53( Issue 41) pp:11041-11045
Publication Date(Web):
DOI:10.1002/anie.201406192

Abstract

We present here a highly efficient NHC-catalyzed kinetic resolution of a wide range of 1,1′-biaryl-2,2′-diols and amino alcohols to provide them in uniformly ≥99 % ee. This represents the first highly enantioselective catalytic acylation of axially chiral alcohols. The aldehyde backbone that is incorporated into the chiral acyl azolium intermediate was found to have a significant effect on the enantioselectivity of the process.

Co-reporter:Yuan Huang, Licheng Yang, Panlin Shao and Yu Zhao  
Chemical Science 2013 vol. 4(Issue 8) pp:3275-3281
Publication Date(Web):05 Jun 2013
DOI:10.1039/C3SC50973G
We have demonstrated that bidentate Lewis base catalysts can be constructed based on the Cinchona alkaloid structure that promote highly stereoselective reactions of allyl- and crotyltrichlorosilane with aromatic as well as aliphatic aldehydes (90–99% ee, >98% diastereoselectivity). The catalysts are available in a one-pot procedure in >70% yield from cheap starting materials and promote the allylation reactions at ambient temperature. Gram scale reactions with catalyst recovery and reuse showcased the practicality of the catalytic system.
Co-reporter:Dr. Shenci Lu;Si Bei Poh;Woon-Yew Siau ; Yu Zhao
Angewandte Chemie International Edition 2013 Volume 52( Issue 6) pp:1731-1734
Publication Date(Web):
DOI:10.1002/anie.201209043
Co-reporter:Dr. Shenci Lu;Si Bei Poh;Woon-Yew Siau ; Yu Zhao
Angewandte Chemie 2013 Volume 125( Issue 6) pp:1775-1778
Publication Date(Web):
DOI:10.1002/ange.201209043
Co-reporter:Yuan Huang, Licheng Yang, Panlin Shao and Yu Zhao
Chemical Science (2010-Present) 2013 - vol. 4(Issue 8) pp:NaN3281-3281
Publication Date(Web):2013/06/05
DOI:10.1039/C3SC50973G
We have demonstrated that bidentate Lewis base catalysts can be constructed based on the Cinchona alkaloid structure that promote highly stereoselective reactions of allyl- and crotyltrichlorosilane with aromatic as well as aliphatic aldehydes (90–99% ee, >98% diastereoselectivity). The catalysts are available in a one-pot procedure in >70% yield from cheap starting materials and promote the allylation reactions at ambient temperature. Gram scale reactions with catalyst recovery and reuse showcased the practicality of the catalytic system.
Co-reporter:Min Wang, Zi-Qiang Rong and Yu Zhao
Chemical Communications 2014 - vol. 50(Issue 97) pp:NaN15312-15312
Publication Date(Web):2014/10/16
DOI:10.1039/C4CC07788A
NHC-catalyzed divergent annulation of enals with heterocyclic enones was developed to produce benzofuran/indole-containing ε-lactones or spiro-heterocycles in a highly diastereo- and enantioselective fashion. The chemo-selectivity controlled by the chiral catalyst backbone is particularly noteworthy.
Co-reporter:Hui-Jie Pan, Teng Wei Ng and Yu Zhao
Chemical Communications 2015 - vol. 51(Issue 59) pp:NaN11910-11910
Publication Date(Web):2015/06/17
DOI:10.1039/C5CC03399C
An efficient Lewis acid-assisted, iron-catalyzed amination of alcohols using borrowing hydrogen methodology was developed. In particular, silver fluoride was identified to be a highly effective additive to overcome the low efficiency in the amination of secondary alcohols catalyzed by Knölker's complex.
Co-reporter:Hui-Jie Pan, Teng Wei Ng and Yu Zhao
Organic & Biomolecular Chemistry 2016 - vol. 14(Issue 24) pp:NaN5493-5493
Publication Date(Web):2015/11/03
DOI:10.1039/C5OB02119G
An iron-catalyzed transfer hydrogenation of N-aryl and N-alkyl imines using isopropanol as the hydrogen donor is reported for the first time. A combination of two iron complexes serving different roles is the key for the success of this catalytic system. As a result, an environmentally friendly and precious metal-free transfer hydrogenation of imines has been developed. The use of a suitable co-catalyst as an activator not only led to efficient transfer hydrogenation, but also showed potential in enantioselective transformation.
Co-reporter:Xiao-Jiao Peng, Yee Ann Ho, Zhi-Peng Wang, Pan-Lin Shao, Yu Zhao and Yun He
Inorganic Chemistry Frontiers 2017 - vol. 4(Issue 1) pp:NaN85-85
Publication Date(Web):2016/10/20
DOI:10.1039/C6QO00555A
The first enantioselective formal [3 + 2] cycloaddition of α-unsubstituted isocyanoacetates with protecting-group-free methyleneindolinones was developed. A variety of optically enriched 3,3′-pyrrolidinyl spirooxindoles were obtained in excellent yields, and diastereo- and enantioselectivities (up to 99% yield, >20:1 dr, 99% ee) with low catalyst loading under mild reaction conditions.
Co-reporter:Tang-Lin Liu, Ji’En Wu and Yu Zhao
Chemical Science (2010-Present) 2017 - vol. 8(Issue 5) pp:NaN3890-3890
Publication Date(Web):2017/03/20
DOI:10.1039/C7SC00483D
An unconventional cleavage of an unstrained carbon–carbon bond in allylic alcohols can be induced by the use of N-fluorobenzenesulfonimide (NFSI) under catalyst-free conditions. By using this simple procedure, a wide range of functionalized Z-fluoroalkenes can be accessed in high yield and selectivity from cyclic and acyclic allylic alcohols.
2H-Indol-2-one, 1,3-dihydro-3-hydroxy-3-(2-propenyl)-, (3S)-
1(2H)-Naphthalenone, 3,4-dihydro-2-hydroxy-2-(phenylmethyl)-, (2R)-
Benzenepropanoic acid, α-ethenylidene-4-fluoro-, ethyl ester
Benzenemethanamine, N-(1-phenylethylidene)-, (Z)-
Benzenepropanoic acid, α-ethenylidene-2-fluoro-, ethyl ester
3(2H)-Benzofuranone, 2-[(2-methylphenyl)methylene]-, (Z)-
[2,2'-Binaphthalene]-1,1'-diol, 3,3'-diphenyl-
Benzamide, 2-(diphenylphosphino)-N-[(1S)-1-(1-naphthalenyl)ethyl]-
4-Pentenoic acid, 2-ethenylidene-, ethyl ester
5-Hexen-3-ol, 1-(phenylmethoxy)-, (3R)-