Features of the behavior of 4-amino-5-carboxamido-1,2,3-triazole in multicomponent heterocyclizations with carbonyl compounds

• Eugene S. Gladkov,
• Katerina A. Gura,
• Svetlana M. Sirko,
• Sergey M. Desenko,
• Ulrich Groth and
• Valentin A. Chebanov

Beilstein J. Org. Chem. 2012, 8, 2100–2105, doi:10.3762/bjoc.8.236

• ; heterocycle; microwave-assisted synthesis; multicomponent reaction; ultrasound-assisted synthesis; Introduction Multicomponent reactions (MCRs) [1][2][3][4] involving polyfunctional aminazoles as a key reagent are challenging objectives in the modern chemistry of heterocyclic compounds dealing with the

• the viewpoint of yields and purity of the target compounds were observed when ultrasound-assisted method C was applied. Sequential reaction via synthesis of arylidenecyclohexanone 10 also gave as sole reaction product compound 7 under all the methods of activation applied. However, microwave heating

• [1,2,3]triazolo[5,1-b]quinazoline-3-carboxamides 7 or 9 under all the reactions conditions studied; however, the ultrasound-assisted procedure is the method of choice for this heterocyclization. For all the MCRs studied, changes in the directions of the heterocyclizations were not observed when microwave

Cyclodextrin-based nanosponges as drug carriers

• Francesco Trotta,
• Marco Zanetti and
• Roberta Cavalli

Beilstein J. Org. Chem. 2012, 8, 2091–2099, doi:10.3762/bjoc.8.235

• the Boson peak and Brillouin frequency [16]. Using ultrasound-assisted synthesis and a suitable cross-linker molar ratio, spherical nanosponges of submicron size were obtained [17]. The cross-linking produces a powder consisting of cyclodextrin connected by nanochannels to form a cage-like structure

• release oxygen both in the presence and in the absence of ultrasound (US). Oxygen permeation through a silicone membrane was obtained by using a nanosponge/hydrogel combination system All types of nanosponges were able to encapsulate, store and release oxygen for prolonged periods. Ultrasound enhanced the

An efficient access to the synthesis of novel 12-phenylbenzo[6,7]oxepino[3,4-b]quinolin-13(6H)-one derivatives

• Wentao Gao,
• Guihai Lin,
• Yang Li,
• Xiyue Tao,
• Rui Liu and
• Lianjie Sun

Beilstein J. Org. Chem. 2012, 8, 1849–1857, doi:10.3762/bjoc.8.213

• hydrochloric acid. Subsequently, we reported a similar reaction under ultrasound irradiation conditions by using KHSO4 as catalyst [36]. Although the two methodologies are elegant and impressive, our attempts to follow both routes to synthesize 2 were frustrated by very low yields. In this regard, Bose et al

Synthesis of trifunctional cyclo-β-tripeptide templates

• Frank Stein,
• Tahir Mehmood,
• Tilman Plass,
• Javid H. Zaidi and
• Ulf Diederichsen

Beilstein J. Org. Chem. 2012, 8, 1576–1583, doi:10.3762/bjoc.8.180

• (39.4 mg, 36.0 μmol, 1.00 equiv) was dissolved in a solution of 20% piperidine in DMF (500 μL) and stirred for 3 min at 50 °C (25 W) by using a manual discover SPS ultrasound peptide synthesizer. Afterwards, the crude peptide was precipitated with ice-cold MTBE (1 × 15 mL) and the title compound was

Regioselectivity in the multicomponent reaction of 5-aminopyrazoles, cyclic 1,3-diketones and dimethylformamide dimethylacetal under controlled microwave heating

• Kamal Usef Sadek,
• Ramadan Ahmed Mekheimer,
• Tahany Mahmoud Mohamed,
• Moustafa Sherief Moustafa and
• Mohamed Hilmy Elnagdi

Beilstein J. Org. Chem. 2012, 8, 18–24, doi:10.3762/bjoc.8.3

• ., either kinetic or thermodynamic [11][12][13]. It has been reported that the use of microwave or ultrasound irradiation provides an additional parameter for synthetic selectivity [14][15][16][17]. Results and Discussion The multicomponent reaction of 5-aminopyrazoles, dimedone and aromatic aldehydes was

A novel and facile synthesis of 3-(2-benzofuroyl)- and 3,6-bis(2-benzofuroyl)carbazole derivatives

• Wentao Gao,
• Meiru Zheng and
• Yang Li

Beilstein J. Org. Chem. 2011, 7, 1533–1540, doi:10.3762/bjoc.7.180

• described. The synthesis mainly relies on the ultrasound-assisted Rap–Stoermer reaction of 3-chloroacetyl- (1) or 3,6-dichloroacetyl-9-ethyl-9H-carbazole (4) with various salicylaldehydes 2a–k as well as 2-hydroxy-1-naphthaldehyde (2l) in CH3CN with the presence of PEG-400 as catalyst. The procedure offers

• easy access to benzofuroylcarbazoles in short reaction times and the products are obtained in moderate to good yields. Keywords: 2-benzofuroyl; carbazole; PEG-400; Rap–Stoermer reaction; salicylaldehydes; ultrasound-assisted; Introduction Carbazole, and especially heterocycle-containing carbazole

• of only 29%. There was no further improvement in the yields upon increasing the amount of catalyst or the reaction time. As a result, attempts to find an alternative approach are still very desirable. Recently, the ultrasound technique has increasingly been used in synthetic organic chemistry. A

First synthesis of 2-(benzofuran-2-yl)-6,7-methylene dioxyquinoline-3-carboxylic acid derivatives

• Wentao Gao,
• Jia Liu,
• Yun Jiang and
• Yang Li

Beilstein J. Org. Chem. 2011, 7, 210–217, doi:10.3762/bjoc.7.28

• ethyl 4-chloro-3-oxobutanoate using KHSO4 as catalyst under ultrasound irradiation conditions. The targeted compounds 3a–h were obtained in good yields of 52–82% and their structures were established based on spectral data and elemental analyses. Keywords: benzofuran; Friedländer condensation

• carried out under ultrasound irradiation conditions at 80 °C using KHSO4 as catalyst in 80% EtOH as solvent. The resulting product 5 was obtained in good yield (74%) after purification by a flash chromatography on silica gel (eluent: petroleum ether/ethyl acetate = 5:1). The next step involves the

• . Biological activity of the synthesized compounds remains to be studied. Experimental Melting points (uncorrected) were determined with a WRS-1B melting point apparatus and are uncorrected. Ultrasonication was performed in a KQ-250B medical ultrasound cleaner with a frequency of 40 KHz and output power of

Novel multi-responsive P2VP-block-PNIPAAm block copolymers via nitroxide-mediated radical polymerization

• Cathrin Corten,
• Katja Kretschmer and
• Dirk Kuckling

Beilstein J. Org. Chem. 2010, 6, 756–765, doi:10.3762/bjoc.6.89

• were prepared 60 min before measurements. The solutions were treated with ultrasound for 5 min and filtered through PES filters (pore size 0.45 µm). Synthesis 2,2,5-Trimethyl-3-(1-phenylethoxy)-4-phenyl-3-azahexane (St-TIPNO) (1) and the corresponding nitroxide 2,2,5-trimethyl-4-phenyl-3-azahexane 3

An improved synthesis of 1,3,5-triaryl- 2-pyrazolines in acetic acid aqueous solution under ultrasound irradiation

• Ji-Tai Li,
• Xiao-Hui Zhang and
• Zhi-Ping Lin

Beilstein J. Org. Chem. 2007, 3, No. 13, doi:10.1186/1860-5397-3-13

• from drawbacks such as long reaction times, cumbersome product isolation procedures and environmental concerns. Organic reactions in aqueous media have attracted increasing interest recently because of environmental issues and the understanding of biochemical processes. Ultrasound has increasingly been

• used in organic synthesis in the last three decades. A large number of organic reactions can be carried out in higher yields, shorter reaction time or milder conditions under ultrasound irradiation. Results Preparation of a series of 1,3,5-triaryl-2-pyrazolines through the reaction of chalcones and

• phenylhydrazine hydrochloride was carried out in 83–96% yield within 1.5–2 h in sodium acetate-acetic acid aqueous solution under ultrasound irradiation. Conclusion We have described a practical and convenient procedure for the synthesis of 1,3,5-triaryl-2-pyrazolines in sodium acetate-acetic acid aqueous

Photosonochemical catalytic ring opening of α-epoxyketones

• Hamid R. Memarian and
• Ali Saffar-Teluri

Beilstein J. Org. Chem. 2007, 3, No. 2, doi:10.1186/1860-5397-3-2

• Hamid R. Memarian Ali Saffar-Teluri Department of Chemistry, Faculty of Science, University of Isfahan, 81746-73441, Isfahan, Iran 10.1186/1860-5397-3-2 Abstract The combination of ultrasound and photochemical methods has been used for the catalytic ring opening of α-epoxyketones by 1-benzyl

• -2,4,6-triphenylpyridinium tetrafluoroborate (NBTPT) as photocatalyst in methanol. Sonication of these compounds in the presence of NBTPT did not result in the opening of epoxide ring, but the use of ultrasound increased the rate of photoreaction. Background The advantages of ultrasound-assisted

• chemical reactions include higher yields, shorter reaction times and milder reaction conditions when compared with classical methods. [1][2][3][4][5] The effect of ultrasound has mostly been shown by increasing the yields of reactions and in some cases changing the ratio of products formed. The most

EcoScale, a semi- quantitative tool to select an organic preparation based on economical and ecological parameters

• Koen Van Aken,
• Lucjan Strekowski and
• Luc Patiny

Beilstein J. Org. Chem. 2006, 2, No. 3, doi:10.1186/1860-5397-2-3

• , the application of unconventional techniques such as microwave irradiation, ultrasound or photochemistry, and the need for an inert atmosphere, especially in a glove box, downgrade the overall quality of the synthesis. 5. Temperature/time The reaction temperature and time are closely related. In an