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22 Feb 10:10

[ASAP] Optical Terpene and Terpenoid Sensing: Chiral Recognition, Determination of Enantiomeric Composition and Total Concentration Analysis with Late Transition Metal Complexes

by Zeus A. De los Santos and Christian Wolf*

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Journal of the American Chemical Society
DOI: 10.1021/jacs.9b13910
03 Dec 08:56

Iridium‐Catalyzed Cycloisomerization of Alkynoic Acids: Synthesis of Unsaturated Lactones

by Yi Huang, Xianghe Zhang, Xiu-Qin Dong, Xumu Zhang
Advanced Synthesis & Catalysis Iridium‐Catalyzed Cycloisomerization of Alkynoic Acids: Synthesis of Unsaturated Lactones


Abstract

The iridium‐catalyzed cycloisomerization of various alkynoic acids was successfully developed, and a series of five‐, six‐, and especially seven‐membered unsaturated lactones were constructed with moderate yields and excellent regioselectivities (up to 68% yield, >99:1 rr). In addition, the indole compound can be easily prepared with 75% yield through this efficient synthetic methodology. Moreover, a plausible mechanism for this Ir‐catalyzed cycloisomerization of alkynoic acids was proposed.

04 Aug 08:29

N-heterocyclic Carbene–Cu-Catalyzed Enantioselective Conjugate Additions with Alkenylboronic Esters as Nucleophiles

by Qinglei Chong, Zhenting Yue, Shuoqing Zhang, Chonglei Ji, Fengchang Cheng, Haiyan Zhang, Xin Hong and Fanke Meng

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ACS Catalysis
DOI: 10.1021/acscatal.7b02132
02 Aug 10:55

Isonicotinate Ester Catalyzed Decarboxylative Borylation of (Hetero)Aryl and Alkenyl Carboxylic Acids through N-Hydroxyphthalimide Esters

by Wan-Min Cheng, Rui Shang, Bin Zhao, Wei-Long Xing and Yao Fu

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Organic Letters
DOI: 10.1021/acs.orglett.7b01950
23 May 09:41

Calcium(II)-Catalyzed Alkenylation of N-Acyliminiums and Related Ions with Vinylboronic Acids

by Chenxiao Qi, Vincent Gandon, David Lebœuf

Abstract

Efficient C−C bond-forming reactions between N,O-acetals and vinylboronic acids were achieved via a calcium(II)-catalyzed formation of a N-acyliminium intermediate or a related ion. This strategy can give a rapid access to a wide variety of alkenyl-functionalized nitrogen-containing compounds in good to excellent yields under simple reaction conditions.

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22 May 07:09

Chemoselective Reduction of Azlactones Using Schwartz’s Reagent

by Danielle L. J. Pinheiro, Eloah P. Ávila, Gabriel M. F. Batista and Giovanni W. Amarante

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The Journal of Organic Chemistry
DOI: 10.1021/acs.joc.7b00820
22 May 06:28

Arylative Intramolecular Allylation of Ketones with 1,3-Enynes Enabled by Catalytic Alkenyl-to-Allyl 1,4-Rhodium(I) Migration

by Benjamin M. Partridge, Michael Callingham, William Lewis, Hon Wai Lam

Abstract

Alkenyl-to-allyl 1,4-rhodium(I) migration enables the generation of nucleophilic allylrhodium(I) species by remote C−H activation. This new mode of reactivity was employed in the diastereoselective reaction of arylboron reagents with substrates containing a 1,3-enyne tethered to a ketone, to give products containing three contiguous stereocenters. The products can be obtained in high enantioselectivities using a chiral sulfur-alkene ligand.

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On the move: The title migration enables the generation of nucleophilic allylrhodium(I) species by remote C−H activation. This new mode of reactivity was employed in the diastereoselective reaction of arylboron reagents with substrates containing a 1,3-enyne tethered to a ketone, to give products containing three contiguous stereocenters. The products can be obtained in high enantioselectivities using a chiral sulfur-alkene ligand.

22 May 06:27

Rh-Catalyzed Anti-Markovnikov Hydrocyanation of Terminal Alkynes

by Fei Ye, Junting Chen and Tobias Ritter

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Journal of the American Chemical Society
DOI: 10.1021/jacs.7b03749
19 May 14:32

B(C6F5)3-Catalyzed (Convergent) Disproportionation Reaction of Indoles

by Yuxi Han, Sutao Zhang, Jianghua He and Yuetao Zhang

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Journal of the American Chemical Society
DOI: 10.1021/jacs.7b03534
22 Mar 09:24

B(C6F5)3-Catalyzed Selective Chlorination of Hydrosilanes

by Karina Chulsky, Roman Dobrovetsky

Abstract

The chlorination of Si−H bonds often requires stoichiometric amounts of metal salts in conjunction with hazardous reagents, such as tin chlorides, Cl2, and CCl4. The catalytic chlorination of silanes often involves the use of expensive transition-metal catalysts. By a new simple, selective, and highly efficient catalytic metal-free method for the chlorination of Si−H bonds, mono-, di-, and trihydrosilanes were selectively chlorinated in the presence of a catalytic amount of B(C6F5)3 or Et2O⋅B(C6F5)3 and HCl with the release of H2 as a by-product. The hydrides in di- and trihydrosilanes could be selectively chlorinated by HCl in a stepwise manner when Et2O⋅B(C6F5)3 was used as the catalyst. A mechanism is proposed for these catalytic chlorination reactions on the basis of competition experiments and density functional theory (DFT) calculations.

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Cl-early a winning combination: Hydrosilanes underwent selective chlorination upon treatment with HCl in the presence of a catalytic amount of B(C6F5)3 with the liberation of H2 (see scheme). For the chlorination of di- and trihydrosilanes, the adduct Et2O⋅B(C6F5)3 was found to be the more selective catalyst.

20 Mar 12:15

Ring-opening of cyclic ethers by aluminum hydridotriphenylborate

Chem. Commun., 2017, 53,3493-3496
DOI: 10.1039/C7CC01159H, Communication
Debabrata Mukherjee, Hassan Osseili, Khai-Nghi Truong, Thomas P. Spaniol, Jun Okuda
Ring-opening of THF or THP in the presence of pinacolborane can be catalyzed by a molecular aluminum hydride catalyst [(L)AlH2]2 (L = Me3TACD)/BPh3 and involves an isolable intermediate [(L)AlH][HBPh3].
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