- Silver Mediated Banert Cascade with Carbon Nucleophiles
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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
- Alexander, Juliana R.,Kevorkian, Paul V.,Topczewski, Joseph J.
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p. 3227 - 3230
(2021/05/05)
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- Intercepting the Banert cascade with nucleophilic fluorine: Direct access to α-fluorinated: N H-1,2,3-triazoles
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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
- Alexander,Kevorkian,Topczewski
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p. 5024 - 5027
(2021/05/28)
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- Aromatic Aza-Claisen Rearrangement of Arylpropargylammonium Salts Generated in situ from Arynes and Tertiary Propargylamines
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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.
- Han, Lu,Li, Sheng-Jun,Zhang, Xue-Ting,Tian, Shi-Kai
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p. 3091 - 3097
(2021/01/21)
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- Divergent Mechanisms of the Banert Cascade with Propargyl Azides
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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.
- Alexander, Juliana R.,Packard, Mary H.,Hildebrandt, Alanna M.,Ott, Amy A.,Topczewski, Joseph J.
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p. 3174 - 3181
(2020/03/23)
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- A Unified Strategy for the Synthesis of β-Carbolines, γ-Carbolines, and Other Fused Azaheteroaromatics under Mild, Metal-Free Conditions
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An efficient, unified approach for the synthesis of β-carbolines, γ-carbolines, and other fused azaheteroaromatics has been realized under metal-free conditions, from propargylic amines and (hetero)aromatic aldehydes. This unified strategy provides β- and
- Uredi, Dilipkumar,Motati, Damoder Reddy,Blake Watkins
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supporting information
p. 6336 - 6339
(2018/10/15)
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- One-Pot Synthesis of Polysubstituted Imidazoles via Sequential Staudinger/aza-Wittig/Ag(I)-Catalyzed Cyclization/Isomerization
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A new one-pot preparation of polysubstituted imidazoles by a Staudinger/aza-Wittig/Ag(I)-catalyzed cyclization/isomerization has been developed. The easily accessible propargylazide derivatives reacted with triphenylphosphine, isocyanates, and amines sequ
- Xiong, Jun,Wei, Xiao,Liu, Zi-Ming,Ding, Ming-Wu
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p. 13735 - 13739
(2017/12/26)
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- Palladium(II)-Catalyzed Directed anti-Hydrochlorination of Unactivated Alkynes with HCl
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A regioselective anti-hydrochlorination of unactivated alkynes is reported. The reaction utilizes in situ generated HCl as the source of both the Cl- and H+ and is catalyzed by palladium(II) acetate, with loadings as low as 25 ppm. Removable picolinamide and 8-aminoquinoline bidentate directing groups are used to control the regioselectivity of the chloropalladation step and stabilize the resulting alkenylpalladium(II) intermediate for subsequent protodepalladation. This method provides access to a broad array of substituted alkenyl chlorides in excellent yields and with high regioselectivity. The products from this transformation were successfully derivatized via Stille coupling to a variety of trisubstituted alkene products. Reaction progress kinetic analysis was performed, shedding light on a possible mechanism for this catalytic process.
- Derosa, Joseph,Cantu, Annabelle L.,Boulous, Mark N.,O'Duill, Miriam L.,Turnbull, Joshua L.,Liu, Zhen,De La Torre, Daizy M.,Engle, Keary M.
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supporting information
p. 5183 - 5193
(2017/05/04)
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- Torquoselectivity in the nazarov reactions of allenyl vinyl ketones
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Nazarov reactions mediated by BF3-etherate of a series of carbon-substituted allenyl vinyl ketones provided intermediates in which substituents on the termini of the allenes had rotated away from the vinyl moieties, and these intermediates were
- Morgan, Timothy D. R.,Leblanc, Luc M.,Ardagh, Giselle H.,Boyd, Russell J.,Burnell, D. Jean
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p. 1042 - 1051
(2015/01/30)
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- CHIRAL RECOGNITION OF ALLENIC HYDROCARBONS BY 1H NMR
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The syntheses of the allenes (+/-)-1, (+/-)-4, and (+/-)-6 as well as of the enriched samples (-)-1, (-)-4 and (-)-6 are described. 1H NMR shifts and splittings induced by a mixture of the achiral salt Ag(fod) and the optically active complex (+)-Yb(hfbc)
- Mannschreck, A.,Munninger, W.,Burgemeister, T.,Gore, J.,Cazes, B.
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p. 399 - 408
(2007/10/02)
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