CuI-Catalyzed intramolecular aminocyanation of terminal alkynes in N-(2-ethynylphenyl)-N-sulfonylcyanamides via Cu–vinylidene intermediates

Abstract

CuI-Catalyzed intramolecular aminocyanation of terminal alkynes in N-(2-ethynylphenyl)-N-sulfonylcyanamides was initiated by the formation of Cu-acetylide to trigger N-CN bond cleavage of the N-sulfonylcyanamide moiety followed by CN migration to form a β-cyano Cu-vinylidene intermediate. Subsequently, the indole ring closure furnished the corresponding 1-sulfonyl-3-cyanoindoles.

Copper Mediated Chemo‐ and Stereoselective Cyanation Reactions

“…The catalytic material tolerated a broad range of substrate with moderate to excellent yields (See Figure 123). [128] …”

“…The catalytic material tolerated a broad range of substrate with moderate to excellent yields (See Figure 123). [128] Cu(MeCN) 4 PF 6 /dtbpy/Na 2 CO 3 catalyzed multicomponent domino reaction involving cross-coupling of oxime esters, styrenes, and boronic acids were performed under photochemical conditions using blue LED as the light source. The catalytic generation of an iminyl radical from a redox-active oxime ester and generation of cyano alkyl radical due to cleavage of CÀ C bond was the main step of this reaction.…”

Direct cyanation, hydrocyanation, dicyanation and cyanofunctionalization of alkynes

“…A series of 1-sulfonyl-3cyanoindoles 34 was obtained in 53-83% yields when aminocyanation ring closure of N-(2-ethynylphenyl)-N-sulfonylcyanamides 33 was carried out in 1,4-dioxane with CuI as the catalyst, and Na 2 CO 3 as the base under argon at 80 C, and the reaction could be completed within 3 hours (Scheme 16). 34 The plausible mechanism was proposed (Scheme 17). First, p-coordination of alkyne and nitrile moieties to the copper centre was occurred to form a substrate-copper complex K. Subsequently, the N-tosyl-2-alkynylanilide cyanocopper complex L was obtained through the heterolytic cleavage of the N-CN bond by the migration of the electrophilic cyano group to the copper centre.…”

“…Protonation of M furnished the desired product 34 and regained the Cu(I) catalyst to continue the catalytic cycle. 34 A visible-light-mediated direct cyanomethylation of aryl alkynoates for synthesis of 3-cyanomethylated coumarins was demonstrated by Li in 2018. In the presence of fac-Ir(ppy) 3 as a photocatalyst and NaHCO 3 as a base under blue-light irradiation in acetone at room temperature, direct cyanomethylation of aryl alkynoates 35 with 2-bromoacetonitrile proceeded smoothly to afford the desired 3-cyanomethylated coumarins 36 in moderate to good yields.…”

Recent Advances in Cyanamide Chemistry: Synthesis and Applications

“…Chien and Co-workers synthesized a series of 1-sulfonyl-3-cyanoindole ( 62 ) products by CuI catalyzed intramolecular aminocyanation of N -(2-ethynylphenyl)- N -sulfonyl-cyanamides 61 ( Scheme 15 ) [ 29 ]. In the presence of CuI and Na 2 CO 3 , both terminal ethynyl and TMS-ethynyl- N -tosylcyanamide-substituted aryl-derivatives underwent intramolecular aminocyanation across the C–C triple bond leading to the 3-cyanoindole skeleton.…”