2-Ethynylaniline Derivatives Research Articles

A Convenient, Efficient, and Inexpensive Copper(I) Complex Catalyzed Sonogashira Cross-Coupling of o-Iodoanilines with Terminal Alkynes

AbstractUsing (PPh3)2CuBH4 as catalyst, a convenient, efficient, and inexpensive palladium-free catalytic system has been developed to catalyze Sonogashira cross-coupling of o-iodoanilines with terminal alkynes under an air atmosphere to give a range of 2-ethynylaniline derivatives with up to 99% yield. This protocol is amenable to scale up. Notable features of the approach include good functional group tolerance, air atmosphere, and excellent yields.

Thiol-stabilized atomically precise, superatomic silver nanoparticles for catalysing cycloisomerization of alkynyl amines

Abstract Both the electronic and surface structures of metal nanomaterials play critical roles in determining their chemical properties. However, the non-molecular nature of conventional nanoparticles makes it extremely challenging to understand the molecular mechanism behind many of their unique electronic and surface properties. In this work, we report the synthesis, molecular and electronic structures of an atomically precise nanoparticle, [Ag206L72]q (L = thiolate, halide; q = charge). With a four-shell Ag7@Ag32@Ag77@Ag90 Ino-decahedral structure having a nearly perfect D5h symmetry, the metal core of the nanoparticle is co-stabilized by 68 thiolate and 4 halide ligands. Both electrochemistry and plasmonic absorption reveal the metallic nature of the nanoparticles, which is explained by density functional theory calculations. Electronically, the nanoparticle can be considered as a superatom, just short of a major electron shell closing of 138 electrons (q = –4). More importantly, many of ligands capping on the nanoparticle are labile due to their low-coordination modes, leading to high surface reactivity for catalysing the synthesis of indoles from 2-ethynylaniline derivatives. The results exemplify the power of the atomic-precision nanocluster approach to catalysis in probing reaction mechanisms and in revealing the interplay of heterogeneous reactivities, electronic and surface structural dynamics, thereby providing ways for optimization.

Simultaneous Functionalization and Cyclization of 2-Ethynylaniline Derivatives to Indoles

Simultaneous Functionalization and Cyclization of 2-Ethynylaniline Derivatives to Indoles

Synthesis of 4-methyl-2,3-disubstituted quinoline scaffolds via environmentally benign Fe(iii) catalysed sequential condensation, cyclization and aromatization of 1,3-diketone and 2-ethynylaniline

Environmentally benign Fe(III)-catalysed sequential condensation, cyclization and aromatization of 1,3-diketone and 2-ethynylaniline derivatives to the substituted quinoline scaffolds with good to excellent yield in shorter reaction time is described.

Hg(OTf)2‐Catalyzed Cycloisomerization of 2‐Ethynylaniline Derivatives Leading to Indoles.

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Hg(OTf) 2-Catalyzed cycloisomerization of 2-ethynylaniline derivatives leading to indoles

Cycloisomerization of 2-ethynylaniline derivatives catalyzed by mercuric triflate afforded indole derivatives in excellent yield under mild reaction conditions with high catalytic turnover up to 100 times.

Palladium(II)-catalyzed tandem intramolecular aminopalladation of alkynylanilines and conjugate addition for synthesis of 2,3-disubstituted indole derivatives

An efficient method for the synthesis of 2,3-disubstituted indoles with high selectivity from 2-ethynylaniline derivatives and α,β-unsaturated carbonyl compounds was developed. This Pd(II)-catalyzed reaction involves tandem intramolecular aminopalladation, olefin insertion and protonolysis of the carbon-palladium bond with the regeneration of Pd(II) species in the presence of halide ions.

Direct Synthesis of Polysubstituted Quinoline Derivatives by InBr3-Promoted Dimerization of 2-Ethynylaniline Derivatives

InBr3 promotes the dimerization of 2-ethynylaniline derivatives containing an unsubstituted terminal carbon leading to the production of polysubstituted quinoline derivatives in good yield.

Mild and efficient cyclization reaction of 2-ethynylaniline derivatives to indoles in aqueous medium

Results of the optimized cyclization reaction of 2-ethynylaniline derivatives to indoles catalyzed by copper(II) salts are described. The reactions can be carried out in a mixture of H 2O and MeOH in the presence of 1-ethylpiperidine at room temperature. These conditions can be applied to a bulky substrate, which is difficult to be cyclized efficiently by existing reaction conditions. Furthermore, this reaction condition was applied to a catalyst recycling reaction system.

Synthesis of 4H-3,1-benzoxazines, quinazolin-2-ones, and quinoline-4-ones by palladium-catalyzed oxidative carbonylation of 2-ethynylaniline derivatives.

An effective and straightforward approach to the synthesis of 4H-3,1-benzoxazines 3 and 4, quinazolin-2-ones 5, and quinoline-4-one derivatives 6 and 7 is provided by palladium-catalyzed cyclization-alkoxycarbonylation of variously substituted 2-(trimethylsilanyl)ethynylaniline amide or urea derivatives 2. Reactions are carried out in 7:1 MeCN/MeOH at 65 or 75 degrees C in the presence of catalytic amounts of 10% Pd/C in conjunction with Bu(4)NI and KF and under 2.4 MPa of a 3:1 mixture of CO and air. Anti and syn 6-exo-dig cyclization modes account for the formation of the two stereoisomers. Isomerization of the vinylpalladium intermediate may occur as well. Formation of a double carbonylation product 7r and of a gem-dimethoxycarbonylation product 6s, whose structures have been determined by X-ray diffraction analysis, is justified through an unusual type of rearrangement.

Development of an Efficient Procedure for Indole Ring Synthesis from 2-Ethynylaniline Derivatives Catalyzed by Cu(II) Salts and Its Application to Natural Product Synthesis

The development of efficient methods for the indole synthesis catalyzed by Cu(II) salts and its applications were investigated. Cu(OAc)(2) has been proved to be the best catalyst for the synthesis of various 1-p-tolylsulfonyl or 1-methylsulfonylindoles, which have both electron-withdrawing and electron-donating groups on the aromatic ring and C2 position of indoles. For the primary aniline derivatives, Cu(OCOCF(3))(2) showed good activities, while Cu(OAc)(2) was a good catalyst for the cyclization of secondary anilines. This methodology could be applied to the sequential cyclization reaction for the compounds which have the electrophilic part in the same molecule. By prior treatment with KH, the sequential cyclization was realized to provide the tricyclic ring systems, but it was limited to five- and six-membered rings for the second cyclization. Finally, formal and total synthesis of hippadine with the Cu(II)-promoted indole synthesis as the key step was accomplished.

Efficient construction of indole rings from 2-ethynylaniline derivatives catalyzed by copper(II) salts and its application to the tandem cyclization reactions

The efficient cyclization reactions of the N-methanesulfonyl or N-ethoxycarbonyl derivatives of 2-ethynylanilines, functionalized on the benzene ring and/or the acetylene terminal into indoles catalyzed by either Cu(OTf)2 or Cu(OAc)2 are accomplished. The application of this reaction to the tandem cyclization reaction is also described.