Copper(I)‐Catalyzed Regioselective Chan‐Lam N2‐Vinylation of 1,2,3‐Triazoles and Tetrazoles

Abstract

Copper‐catalyzed coupling of π‐deficient NH‐azoles with vinylboronic acids or vinyltrifluoroborate salt provides a direct route to N2‐vinyl‐1,2,3‐triazoles and N2‐vinyltetrazoles. The coupling reaction is efficiently catalyzed by (phen)Cu(PPh3)Br with low catalyst loading (5 mol%) under base‐free conditions. The method is applicable for vinylation of unsubstituted, monosubstituted, and disubstituted 1,2,3‐triazoles with various functionalities with high N2‐selectivity.magnified image

An aerobic copper-mediated domino process for the synthesis of 3-(trifluoromethylseleno)indoles

“…47 This complex could coordinate with the alkyne moiety of 2 to give the copper complex II , which then underwent 5- endo-dig cyclization to form the 3-copper indole intermediate III . The deprotonation of III generated intermediate IV , which was first oxidized by air to give a Cu( iii ) 48,49 intermediate V followed by reductive elimination to furnish the desired product 3 and Cu( i ) species.…”

Recent Developments in N2-Selective Functionalizations of 1,2,3-Triazoles

“…In 2019, Latyshev and co-workers reported an efficient copper(I)-catalyzed N 2 -vinylation of 1,2,3-triazoles 77 with vinylboronic acids or vinyltrifluoroborate salt 78 (Scheme 27). 39 Different from the classical Chan-Lam coupling, air-…”

“…In 2019, Latyshev and co-workers reported an efficient copper(I)-catalyzed N 2 -vinylation of 1,2,3-triazoles 77 with vinylboronic acids or vinyltrifluoroborate salt 78 (Scheme 27 ). 39 Different from the classical Chan–Lam coupling, air-stable Cu(I) complex (phen)Cu(PPh 3 )Br was used as a new catalyst to enable the reaction with low catalyst loading (5 mol%) under base-free conditions. This method was suitable for the vinylation of un-, mono- and disubstituted 1,2,3-triazoles 77 , especially when the C-4 position was substituted by bromine or fluorine, which resulted in high N 2 selectivity.…”

Three copper(II) complexes derived from 2‐methylquinoline and cyclic secondary amines: Synthesis and catalytic application in C—N bond forming reactions

“…[ 26 ] In 2019, Motornov et al developed regioselective N 2 ‐arylation of 1,2,3‐triazoles/tetrazoles employing vinylboronic acids or vinyltrifluoroborate salt as reaction reagents in the presence of 5 mol% (phen)Cu(PPh 3 )Br as a catalyst. [ 27 ] Recently, Akatyev et al studied the catalytic activity of copper complexes with different ligands in Chan–Lam coupling and demonstrated that the dinuclear positively charged copper complex derived from 4‐ t‐ butyl‐2,5‐bis[(quinolinylimino)methyl]phenolate was excellent catalysts for this reaction. [ 28 ] The related evidence indicated that the reaction mechanism of Chan–Lam coupling catalyzed by the dinuclear copper complex might include the Cu(II)/Cu(II) pair, which were coordinated by an oxygen molecule in the formation of CN bond, different from the previous mechanism involving conversion of the Cu(II) complexes to Cu(I) propose by King et al [ 29 ] and Vantourout et al [ 30 ] In addition, hexadentate NHC–copper hydroxide complex [ 31 ] and tetradentate copper(II)–NHC complex [ 32 ] were also synthesized and applied in the coupling reaction of arylboronic acids with nitrogen‐containing nucleophiles.…”