Copper-catalyzed coupling of anthranils and α-keto acids: direct synthesis of α-ketoamides

2019 ◽  
Vol 17 (24) ◽  
pp. 5902-5907 ◽  
Author(s):  
Ping-Gui Li ◽  
Hao Zhu ◽  
Min Fan ◽  
Cheng Yan ◽  
Kai Shi ◽  
...  

Copper-catalyzed coupling of α-keto acids with anthranils is reported for the synthesis of α-ketoamides bearing an aldehyde group via N–O/C–O bond cleavages and C–N bond formation.

2018 ◽  
Vol 20 (16) ◽  
pp. 4736-4739 ◽  
Author(s):  
Jie S. Zhu ◽  
Niklas Kraemer ◽  
Marina E. Shatskikh ◽  
Clarabella J. Li ◽  
Jung-Ho Son ◽  
...  

RSC Advances ◽  
2019 ◽  
Vol 9 (14) ◽  
pp. 7718-7722 ◽  
Author(s):  
Hong Zhang ◽  
Jinhai Shen ◽  
Zhenhui Yang ◽  
Xiuling Cui

An expedient hypervalent iodine(iii)-mediated approach to obtain substituted quinoxalines from readily available enaminones has been developed under mild conditions.


2019 ◽  
Author(s):  
K.M. van Vliet ◽  
Lara H. Polak ◽  
Maxime A. Siegler ◽  
J.I. van der Vlugt ◽  
Célia Fonseca Guerra ◽  
...  

Direct synthetic routes to amidines are desired, as they are widely present in many biologically active compounds and organometallic complexes. N-Acyl amidines in particular can be used as a starting material for the synthesis of heterocycles and have several other applications. Here, we describe a fast and practical copper catalyzed 3-component reaction of aryl acetylenes, amines and easily accessible 1,4,2-dioxazol-5-ones to N-acyl amidines, generating CO<sub>2</sub> as the only by-product. Transformation of the dioxazolones on the Cu-catalyst generates acyl nitrenes that rapidly insert into the copper acetylide Cu-C bond rather than undergoing an undesired Curtius rearrangement. For non-aromatic dioxazolones, [Cu(OAc)(Xantphos)] is a superior catalyst for this transformation, leading to full substrate conversion within 10 minutes. For the direct synthesis of N-benzoyl amidine derivatives from aromatic dioxazolones, [Cu(OAc)(Xantphos)] proved to be inactive, but moderate to good yields were obtained when using simple CuI as the catalyst. Mechanistic studies revealed the aerobic instability of one of the intermediates at low catalyst loadings, but the reaction could still be performed in air for most substrates when using catalyst loadings of 5 mol%. The herein reported procedure does not only provide a new, practical and direct route to N-acyl amidines, but also represents a new type of<br>C-N bond formation.


2020 ◽  
Vol 44 (41) ◽  
pp. 17938-17953
Author(s):  
Abhilash Sharma ◽  
Pranjal Gogoi

A versatile transition-metal free synthetic strategy has been developed for the direct synthesis of 6-substituted indoloquinazolinones from 2-acyl-4-quinazolinones and aryne precursors. This cascade strategy proceeds via successive C–N and C–C bond formation in a single reaction vessel.


2019 ◽  
Vol 97 (4) ◽  
pp. 303-309 ◽  
Author(s):  
Reza Khalifeh ◽  
Faranak Karimzadeh

An efficient and straightforward protocol for direct synthesis of 2H-indazoles is achieved from consecutive condensation of 2-halobenzaldehydes, primary amines, and sodium azide catalyzed by heterogeneous copper nanoparticles on charcoal (Cu/C) is achieved. The recoverable heterogeneous copper nanoparticles on charcoal (Cu/C) catalyst exhibited an impressive activity for the title reaction without any additives (expensive ligands, etc.). A series of structurally diverse 2H-indazoles were prepared in good to excellent yields from easily accessible starting materials by employing this protocol.


2015 ◽  
Vol 21 (3) ◽  
pp. 159-163 ◽  
Author(s):  
T.A. Jenifer Vijay ◽  
Nagarakere C. Sandhya ◽  
C.S. Pavankumar ◽  
Kanchugarakoppal S. Rangappa ◽  
Kempegowda Mantelingu

AbstractAn efficient ligand- and catalyst-free intramolecular S-arylation leading to the direct synthesis of indalothiochromen-4-ones from simple dithioesters under mild conditions has been developed. This method is particularly noteworthy given its experimental simplicity, high generality, and good functional group toleration.


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