Rapid microwave-enhanced, solventless Sonogashira coupling reaction on alumina

Kabalka, George W.; Wang, Lei; Namboodiri, Vasudevan; Pagni, Richard M.

doi:10.1016/s0040-4039(00)00774-7

Cited by 144 publications

(51 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…90 The application of KF-alumina to a wide range of organic reactions has provided more convenient and efficient methods in organic syntheses. [91][92][93][94][95] producing 2-aminothiophene derivatives 23 in good yields. Using the microwave irradiation reaction was carried out in very short times, but alternatively the reaction proceed well also under conventional heating (Table 7).…”

Section: Microwave Accelerated Gewald Synthesismentioning

confidence: 99%

Gewald reaction: synthesis, properties and applications of substituted 2-aminothiophenes

Puterová¹,

Krutošíková²,

Végh³

2010

Arkivoc

177

View full text Add to dashboard Cite

Chemistry of 2-aminothiophenes is arguably one of the most extensive and dynamic field of present-day thiophene research. Since 1961 when first report on the Gewald reaction was reported it became a universal method for synthesis of substituted 2-aminothiophenes and has gained prominence in recent times. The availability of reagents and the mild reaction conditions all contribute to the versatility of this reaction. This review summarizes the synthetic strategies for substituted 2-aminothiophenes. Consequently, details about the proposed mechanism of Gewald-like reactions and the wide scope of substituted 2-aminothiophenes for real life applications.

show abstract

Section: Microwave Accelerated Gewald Synthesismentioning

confidence: 99%

Gewald reaction: synthesis, properties and applications of substituted 2-aminothiophenes

Puterová¹,

Krutošíková²,

Végh³

2010

Arkivoc

177

View full text Add to dashboard Cite

show abstract

“…Thus, several new conditions for the Sonogashira reaction have been reported in order to enhance the utility of the reaction. [13][14][15][16][17] Mori and his co-workers have recently reported that TBAF or tetrabutylammonium hydroxide instead of amines can be employed as a base in the Sonogashira reaction. 18,19) We here report a one-pot indole synthesis from 2-iodoanilines and terminal alkynes using a palladium catalyst in the presence of TBAF, combined with the above two applications of TBAF for cyclization reaction to indole and the Sonogashira reaction.…”

Section: )mentioning

confidence: 99%

Convenient Indole Synthesis from 2-Iodoanilines and Terminal Alkynes by the Sequential Sonogashira Reaction and the Cyclization Reaction Promoted by Tetrabutylammonium Fluoride (TBAF)

Suzuki

Yasaki

Yasuhara

et al. 2003

CHEMICAL & PHARMACEUTICAL BULLETIN

View full text Add to dashboard Cite

Indole derivatives occur widely in natural products and have unique biological activities, 1) and many synthetic methods for construction of the indole ring have been reported. 2)Several cyclization methods from 2-ethynylanilines to indoles have been reported 3) and the syntheses of some natural products were achieved by the cyclization. 4-7)The indole syntheses via 2-ethynylanilines usually require two steps, introduction of the ethynyl group onto the benzene ring and the subsequent cyclization reaction. Concerning the indole cyclization, we have reported the synthesis of 2-substituted indoles from N-(2-iodophenyl)methanesulfonamides and terminal alkynes using palladium catalysts in 1988.8) The indole synthesis was utilized for the resin-bounded system by Zhang, et al. 9) However, the indole synthesis has a limitation in that the reaction requires a methylsulfonyl group on the amino group of the anilines.We have also reported that the cyclization reaction of 2-ethynylanilines with tetrabutylammonium fluoride (TBAF) proceeds at refluxing or room temperature in THF to give 2-substituted indoles in excellent yields without affecting the bromo, chloro, cyano, ethoxycarbonyl, and ethynyl groups. 10)The 2-ethynylanilines, which were the starting materials for indole synthesis by the reaction with TBAF, were prepared by the Sonogashira reaction of 2-iodoanilines and terminal alkynes.Although the Sonogashira reaction, which is the crosscoupling reaction of an aryl halide and a terminal alkyne catalysed by a Pd/Cu system, is a useful method of introduction of an alkynyl moiety to an arene, 11,12) the Sonogashira reaction sometimes requires large amounts of amines as a solvent or co-solvent. Thus, several new conditions for the Sonogashira reaction have been reported in order to enhance the utility of the reaction. [13][14][15][16][17] Mori and his co-workers have recently reported that TBAF or tetrabutylammonium hydroxide instead of amines can be employed as a base in the Sonogashira reaction. 18,19) We here report a one-pot indole synthesis from 2-iodoanilines and terminal alkynes using a palladium catalyst in the presence of TBAF, combined with the above two applications of TBAF for cyclization reaction to indole and the Sonogashira reaction. Results and DiscussionThe reaction conditions for the indole synthesis from Nsubstituted 2-iodoanilines and 1-hexyne were examined as shown in Table 1. When a mixture of N-(2-iodophenyl)-methanesulfonamide (1a) and 1-hexyne with TBAF (3 eq), PdCl 2 (PPh 3 ) 2 (5 mol%), and CuI (10 mol%) in THF was refluxed for 2 h, 2-butyl-1-(methylsulfonyl)indole (2a) was afforded in 86% yield (entry 1). Under the previously reported conditions 8) using triethylamine, the Sonogashira reaction of 1a and 1-hexyne at 80°C for 24 h gave 2a in 64% yield. Thus the reaction of 2-haloanilines having N-sulfonyl groups as a protection groups of amino group, and terminal alkynes using both TBAF and Et 3 N gave the corresponding indoles.The palladium-catalyzed reaction of ethyl N-(2-iodophenyl)carbamate (...

show abstract

“…Advantage of the strongly basic nature of KF/Al 2 O 3, has allowed it to replace organic bases in a number of reactions including Suzuki couplings 11 , condensations 12 , epoxidations 13 , diazetizations 14 , Sonogashira couplings 15 , Knoevenagel reactions 16 and etc.…”

Section: Introductionmentioning

confidence: 99%

Comparison of the Basic Strength of Solid Catalysts in the Synthesis of 2-Styrylbenzoxazoles under Microwave, Ultrasonic Irradiations and Solvent Free Conditions

Tahghighi¹,

Heravi²,

Kobarfard³

et al. 2013

Chem Sci Trans

View full text Add to dashboard Cite

show abstract

Rapid microwave-enhanced, solventless Sonogashira coupling reaction on alumina

Cited by 144 publications

References 12 publications

Gewald reaction: synthesis, properties and applications of substituted 2-aminothiophenes

Gewald reaction: synthesis, properties and applications of substituted 2-aminothiophenes

Convenient Indole Synthesis from 2-Iodoanilines and Terminal Alkynes by the Sequential Sonogashira Reaction and the Cyclization Reaction Promoted by Tetrabutylammonium Fluoride (TBAF)

Comparison of the Basic Strength of Solid Catalysts in the Synthesis of 2-Styrylbenzoxazoles under Microwave, Ultrasonic Irradiations and Solvent Free Conditions

Contact Info

Product

Resources

About