One-pot multicomponent synthesis of substituted 5,7-dihydro-1,6-naphthyridines and 5,6,7,8-tetrahydroquinolines

An one-pot approach was developed for the synthesis of substituted 5,7-dihydro-1,6-naphthyridines and 5,6,7,8-tetrahydroquinolines with moderate to good yields. This pathway is a modified two-step synthesis of Kröhnke pyridine and involves a four-component tandem reaction of N-phenacylpyridinium bromide, aromatic aldehydes, substituted or nitrogen-containing cyclic ketones and a nitrogen source. This multi-component reaction is performed using microwave irradiation heating of the reaction substrates under an environment of NH₄OAc/HOAc.

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Tandem reaction strategy of the Passerini/Wittig reaction based on the in situ capture of isocyanides: One-pot synthesis of heterocycles

This paper reports the tandem reaction strategy of the Passerini/Wittig reaction based on the in situ capture of isocyanides. According to this strategy, plenty of isocyanides have been synthesized, which is immediately used for the tandem reaction of Passerini/Wittig reaction in one pot. Compared to the previous work, this strategy avoids the separation, purification, and storage of isocyanides, which prominently solves the problems of isocyanide-based multicomponent reaction such as: (a) The environmentally unfriendly (strong foul odor), (a) the labile of Isocyanides, (c) high toxicity of isocyanides. In the meantime, in order to expand the application scope of our strategy, 1H-isochromenes and 3H-2-benzoxepin-1-ones have also been synthesized, which undergoes four-step transformations in one-pot. In addition, a relatively credible reaction mechanism has also been proposed, based on a series of control experiments. Furthermore, preliminary testing was performed on biological activity of some obtained compounds; These results showed that the synthesized compounds exhibited certain activity over P. digitatum and P. italicum. ^© 2019 Elsevier Science. All rights reserved.     

One-pot synthesis of chiral bicyclo[3.3.0]octatrienes using diphenylprolinol silyl ether-mediated ene-type reaction

Chiral bicyclo[3.3.0]octatrienes with excellent enantioselectivity were synthesized from the simple starting materials of α,β-unsaturated aldehyde and cyclopentadiene via one-pot operation, which consisted of a diphenylprolinol silyl ether-mediated ene-type reaction, intramolecular addition reaction of cyclopentadiene moiety with aldehyde and dehydration reaction.     

A new and versatile one-pot synthesis of indol-2-ones by a novel Ugi-four-component-Heck reaction

A novel one-pot-synthesis of highly substituted indol-2-ones using a combination of Ugi and Heck reaction (U-4CR-Heck) is described. The synthesized indol-2-ones represent an interesting pharmacological scaffold with four potential points of diversity. Thus, this novel reaction-type is amenable to combinatorial high-throughput screening.     

One-pot synthesis of tetrahydrochromene derivatives catalyzed by lipase

An efficient and green one-pot synthesis route for tetrahydrochromene derivatives was developed. Lipase from Porcine pancreas (PPL) shows excellent catalytic activity and exerts good adaptability to different substrates in the reaction. All the reactions go smoothly and provide tetrahydrochromene derivatives with isolate yield up to 97% under room temperature. This lipase-catalyzed multistep conversion method has provided a new strategy to synthesize chromene derivatives and expanded the application of enzyme in organic synthesis.     

One-pot synthesis of substituted indolines via a copper-catalyzed sequential multicomponent/C-N coupling reaction

One-pot synthesis of 2-(N-sulfonylimino)indolines has been developed. The procedure combines the copper-catalyzed three-component reaction of sulfonyl azides, o-bromophenylacetylenes, and amines and the copper-catalyzed intramolecular C-N coupling in one sequence, which afforded the products in moderate to good yields. The resulting 2-(N-sulfonylimino)indolines could be easily transformed to pharmaceutically valuable oxindoles (indolin-2-ones).     

One-pot multicomponent synthesis of functionalized 2,5-disubstituted-1,3,4-thiadiazine derivatives

An atom-efficient and environmentally friendly approach to the synthesis of 2,5-disubstituted-1,3,4-thidiazine derivatives has been developed. These compounds were synthesized by a reaction of 2-(2-bromoacetyl)benzofuran and thiocarbohydrazide with various aryl aldehydes, acetylacetones, and pthalic anhydrides in good yields. The advantages of this methodology are mild reaction conditions, easy workup procedure, clean reaction profile, shorter reaction time, and a wide range of substrate applicability. The structures of all synthesized compounds were confirmed from their analytical and spectral data.     

One-pot combination of the Wittig olefination with oxidation, hydrogenation, bromination, and photocyclization reactions

Co-polycondensation of tetramethoxysilane, 2-diphenyl(phosphino)ethyltri(ethoxy)silane, and N-2-(aminoethyl)-3-aminopropyltri(methoxy)silane forms a heterogenized tertiary phosphine reagent (HPR) that reacts with benzyl chlorides and aldehydes to give alkenes. This Wittig condensation can be coupled, as a one-pot process, with hydrogenation, oxidation, bromination or photocyclization.     

One-pot reaction for the concise synthesis of spiro[benzofuran-2,2′-naphthalen]-1′-one derivatives

A novel one-pot two-step protocol has been developed to synthesize various spiro[benzofuran-2,2′-naphthalen]-1′-one derivatives from the three-component reaction of tetralones, 2-hydroxyphenyl functionalized α,β-unsaturated ketones, and iodine. One C–C bond and one C–O bond have formed during this process. The notable features of this protocol are simple and mild reaction conditions, applicable to a wide range of readily available starting materials, good yields (up to 91%), and excellent stereoselectivities (up to 97:3).     

A ligand-free Heck reaction catalyzed by the in situ-generated palladium nanoparticles in PEG-400

<正>A ligand-free Heck reaction catalyzed by in situ-generated palladium nanoparticles in PEG-400 has been developed.This catalytic system is a simple and active protocol for the Heck reaction of aryl halides under mild conditions.Comparative experiments demonstrated that the Heck reaction catalyzed by the palladium nanoparticles in situ-generated under the Heck reaction conditions was carried out much quicker than that by the in ex situ-generated ones.     

One-pot Vilsmeier reagent-mediated multicomponent reaction: A direct synthesis of oxazolones and Erlenmeyer azlactones from carboxylic acids

N-Acylation of glycine with carboxylic acids was carried out by using the Vilsmeier reagent. The resulting N-acyl-α-amino acids were subsequently cyclodehydrated into oxazol-5-ones via the Vilsmeier reagent. Finally, treatment of oxazol-5-ones with aldehydes in the presence of the Vilsmeier reagent delivered Erlenmeyer azlactones. By combining these steps, using the Vilsmeier reagent allowed direct one-pot conversion of carboxylic acids into oxazol-5-ones and direct one-pot conversion of carboxylic acids into Erlenmeyer azlactones in the presence of aldehydes. These Vilsmeier reagent-mediated multicomponent reactions proceeded smoothly in reasonable chemical yields at room temperature. The chemical structure of the title compounds was confirmed by spectral data.     

One-pot and catalyst-free synthesis of thiosemicarbazones via multicomponent coupling reactions

A novel and efficient procedure for the synthesis of thiosemicarbazones has been achieved via a multicomponent and catalyst-free reaction of phenyl or p-chlorophenyl isothiocyanate, hydrazine, and aldehydes or ketones. The method afforded 20 thiosemicarbazones in good yields and short reaction time.     

One-pot multicomponent synthesis of novel thiazol-2-imines via microwave irradiation and their antifungal evaluation

Microwave-assisted green approach is developed for an efficient synthesis of thiazol-2-imines under catalyst-free conditions. The desired products are formed by one-pot three-component reaction which is an improvised method for Hantzsch thiazole synthesis. The microwave-assisted protocol gives excellent yields with high purity in just 10–15?min. All the synthesized compounds have been screened for antifungal activity and some of the derivatives show a broad spectrum against fungal pathogens.     

Solid-phase synthesis of modified oligopeptides via Passerini multicomponent reaction

A Passerini multicomponent reaction of N-protected-α-aminoaldehydes, carboxylic acids and solid-supported isocyanides has been successfully performed on Lantern™. The initially formed N-protected-β-amino-α-acyloxyamides gave, by piperidine-promoted deprotection and concomitant acyl migration, β-acylamino-α-hydroxyamides which, by OH-oxidation and cleavage off the solid support, provided β-acylamino-α-oxoamides. Formation and disappearance of the isocyano group has been followed using photoacoustic IR spectroscopy, a fast, reliable and non-disruptive technique that has been successfully applied for the first time to macroscopic solid supports.     

One-pot synthesis of dihydroquinazolinethione-based polycyclic system

A one-pot and diastereoselective synthesis of quinazoline-2(1H)-thione-containing polycyclic compounds is introduced. The reaction process includes [3?+?2] cycloaddition of azomethine ylides for pyrrolidines, Staudinger-aza-Wittig reaction of azides for iminophosphoranes, formation of isothiocyanates, and finally cyclization of amines to isothiocyanates for dihydroquinazolinethiones.