229015-35-4Relevant articles and documents
A boron-oxygen transborylation strategy for a catalytic midland reduction
Nicholson, Kieran,Dunne, Joanne,DaBell, Peter,Garcia, Alexander Beaton,Bage, Andrew D.,Docherty, Jamie H.,Hunt, Thomas A.,Langer, Thomas,Thomas, Stephen P.
, p. 2034 - 2040 (2021/02/20)
The enantioselective hydroboration of ketones is a textbook reaction requiring stoichiometric amounts of an enantioenriched borane, with the Midland reduction being a seminal example. Here, a turnover strategy for asymmetric catalysis, boron.oxygen transb
Aromatic Aza-Claisen Rearrangement of Arylpropargylammonium Salts Generated in situ from Arynes and Tertiary Propargylamines
Han, Lu,Li, Sheng-Jun,Zhang, Xue-Ting,Tian, Shi-Kai
supporting information, p. 3091 - 3097 (2021/01/21)
The charge-accelerated aza-Claisen rearrangement of ammonium salts serves as a key step in the construction of complex nitrogen-containing molecules. However, much less attention has been paid to the aromatic aza-Claisen rearrangement than to the aliphatic one. Herein, we report an unprecedented aromatic aza-Claisen rearrangement of arylpropargylammonium salts, generated in situ from arynes and tertiary propargylamines, delivering structurally diverse 2-propargylanilines in moderate to good yields with high regioselectivity. This rearrangement proceeds in the absence of strong bases or transition metals, is compatible with moisture and air, tolerates a wide variety of functional groups, and is amenable to forming 11- to 13-membered heterocycles with a triple bond. The 2-propargylaniline products were treated with aluminum chloride in ethanol to afford multisubstituted indoles in moderate to excellent yields. Finally, a series of deuterium-labeling experiments was performed to elucidate the reaction mechanism.
Synthesis of Highly Substituted Biaryls by the Construction of a Benzene Ring via in Situ Formed Acetals
Balamurugan, Rengarajan,Manojveer, Seetharaman,Tarigopula, Chandrahas
, p. 11871 - 11883 (2021/09/13)
Herein, we present an interesting method for the construction of a benzene ring using propargylic alcohols and 1,3-dicarbonyls, which involves three new C-C bond formations via cascade alkylation, formylation, annulation, and aromatization to make substituted biaryls. This one-pot Br?nsted acid-promoted protocol utilizes the unique reactivity of the acetal formed under the reaction conditions. Alkynyl methyl ketones could be employed instead of 1,3-dicarbonyls as they are converted to 1,3-dicarbonyls by hydration under the reaction conditions.
Silver Mediated Banert Cascade with Carbon Nucleophiles
Alexander, Juliana R.,Kevorkian, Paul V.,Topczewski, Joseph J.
supporting information, p. 3227 - 3230 (2021/05/05)
The Banert cascade of propargylic azides can be promoted by simple silver salts, and the triazafulvene intermediate can be intercepted by carbon nucleophiles. Various indoles (>25 examples, up to 92% yield) and electron-rich heterocycles were effective. T
Intercepting the Banert cascade with nucleophilic fluorine: Direct access to α-fluorinated: N H-1,2,3-triazoles
Alexander,Kevorkian,Topczewski
supporting information, p. 5024 - 5027 (2021/05/28)
The treatment of propargylic azides with silver(i) fluoride in acetonitrile was found to yield α-fluorinated NH-1,2,3-triazoles via the Banert cascade. The reaction was regioselective and the products result from an initial [3,3] rearrangement. The reacti
Nickel-Catalyzed Asymmetric Friedel-Crafts Propargylation of 3-Substituted Indoles with Propargylic Carbonates Bearing an Internal Alkyne Group
Miyazaki, Yusuke,Zhou, Biao,Tsuji, Hiroaki,Kawatsura, Motoi
supporting information, p. 2049 - 2053 (2020/03/04)
The nickel-catalyzed highly enantioselective Friedel-Crafts propargylation of 3-substituted indoles with propargylic carbonates bearing an internal alkyne group was developed. A wide array of the propargylic carbonates as well as 3-substituted indoles can be applicable to the asymmetric nickel catalysis, providing the corresponding chiral C-3 propargylated indolenine derivatives bearing two vicinal chiral centers in up to 89% yield with up to >99% ee and 94:6 dr (24 examples).
Divergent Mechanisms of the Banert Cascade with Propargyl Azides
Alexander, Juliana R.,Packard, Mary H.,Hildebrandt, Alanna M.,Ott, Amy A.,Topczewski, Joseph J.
, p. 3174 - 3181 (2020/03/23)
Triazoles are privileged heterocycles for a variety of applications. The synthesis of 1H-triazoles can be accomplished by the Banert cascade from propargylic azides. Depending on the substrate and conditions, the Banert cascade can proceed by either a sigmatropic or prototropic mechanism. This report describes the first detailed kinetic analysis of the Banert cascade proceeding by both pathways including substituent effects and KIE. The analysis identified the inflection point in the divergent pathways, allowing future work to predict which Banert products are accessible.
Transition-Metal-Free Synthesis of Electron Rich 1,3-Dienes via Base Promoted Isomerization of Propargylic Ethers
Liu, Chunxiang,Deng, Guogang,Li, Xin,Xu, Yiren,Yu, Kaili,Chen, Wen,Zhang, Hongbin,Yang, Xiaodong
supporting information, p. 483 - 487 (2020/01/25)
Herein, a novel and scalable synthesis of electron rich 1,3-dienes based on KOtBu mediated isomerization of propargylic ether derivatives was developed. This new process features easy handling reaction conditions, transition-metal-free isomerization, high isolated yields, and most of all, it could be used for modification of natural products at late stage functionalizations.
Asymmetric Magnesium-Catalyzed Hydroboration by Metal-Ligand Cooperative Catalysis
Falconnet, Alban,Magre, Marc,Maity, Bholanath,Cavallo, Luigi,Rueping, Magnus
supporting information, p. 17567 - 17571 (2019/11/13)
Asymmetric catalysis with readily available, cheap, and non-toxic alkaline earth metal catalysts represents a sustainable alternative to conventional synthesis methodologies. In this context, we describe the development of a first MgII-catalyzed enantioselective hydroboration providing the products with excellent yields and enantioselectivities. NMR spectroscopy studies and DFT calculations provide insights into the reaction mechanism and the origin of the enantioselectivity which can be explained by a metal-ligand cooperative catalysis pathway involving a non-innocent ligand.
Chemoselective Luche-Type Reduction of α,β-Unsaturated Ketones by Magnesium Catalysis
Jang, Yoon Kyung,Magre, Marc,Rueping, Magnus
supporting information, p. 8349 - 8352 (2019/10/16)
The chemoselective reduction of α,β-unsaturated ketones by use of an economic and readily available Mg catalyst has been developed. Excellent yields for a wide range of ketones have been achieved under mild reaction conditions, short times, and low catalyst loadings (0.2-0.5 mol %).
