A catalyst-free multicomponent domino sequence for the diastereoselective synthesis of (E)-3-[2-arylcarbonyl-3-(arylamino)allyl]chromen-4-ones

• Pitchaimani Prasanna,
• Pethaiah Gunasekaran,
• Subbu Perumal and
• J. Carlos Menéndez

Beilstein J. Org. Chem. 2014, 10, 459–465, doi:10.3762/bjoc.10.43

• . An initial Michael addition–elimination reaction, leading to the exchange between the starting arylamine 3 and dimethylamine, explains the formation of intermediates 4, which were the final reaction products in most investigated solvents. However, in DMF, the enamine moiety of 4 attacks the aldehyde

Four-component reaction of cyclic amines, 2-aminobenzothiazole, aromatic aldehydes and acetylenedicarboxylate

• Hong Gao,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 2934–2939, doi:10.3762/bjoc.9.330

• acetylenedicarboxylate in ethanol at room temperature proceeded very quickly and could be finished to give the expected β-enamino ester in less than twenty minutes [27], while the reaction of normal primary arylamine with acetylenedicarboxylate or propiolate in ethanol at room temperature usually needed more than one

• -toluenesulfonic acid-catalyzed three-component reaction of arylamine, aromatic aldehyde and acetylenedicarboxylate afforded 3-hydroxy-2-pyrrolidinone as main product [28]. In order to improve the reactivity of morpholine in this four-component reaction, p-toluenesulfonic acid was added in the four-component

Mild and efficient cyanuric chloride catalyzed Pictet–Spengler reaction

• Ashish Sharma,
• Mrityunjay Singh,
• Nitya Nand Rai and
• Devesh Sawant

Beilstein J. Org. Chem. 2013, 9, 1235–1242, doi:10.3762/bjoc.9.140

• proved to be a robust catalyst in the 6-endo cyclization. Recently, the Pictet–Spengler reaction has been successfully extended to arylamine substrates [11][12][13][14][15][16][17]. These substrates are designed by replacing the aliphatic amine side chain attached to activated heterocycles, for example

• tryptamine (1), by aromatic amines [11]. Moreover, the aromatic amines can be originated from either carbon or nitrogen of the activated heterocycle. Hence, these substrates are referred to as “modified Pictet–Spengler substrates”. We employed one of the arylamine substrates for our studies (Figure 1). In

• . Substrate 4 furnished the cyclized product faster compared to tryptamine (1). This might be attributed to the enhanced electrophilicity of the imine derived from the arylamine compared to the aliphatic amine as reported earlier [16]. The TCT catalyzed condensation of the Pictet–Spengler substrates 1 and 4

Synthesis of functionalized spiro[indoline-3,4’-pyridines] and spiro[indoline-3,4’-pyridinones] via one-pot four-component reactions

• Li-Juan Zhang,
• Qun Wu,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 846–851, doi:10.3762/bjoc.9.97

• methyl propiolate to give the active adducts, 3-arylaminoacrylates, usually needs more than twelve hours. Thus, we decided firstly to let arylamine and methyl propiolate react in ethanol at room temperature for 24 hours. TLC analysis indicated that the addition reaction had finished, and TLC analysis

• ester A from the addition of arylamine to methyl propiolate. The second reaction is a Knoevenagel condensation of isatin with malononitrile or ethyl cyanoacetate under the catalysis of triethylamine to give the isatylidene deriatives B. The third reaction is a Michael addition of β-enamino ester

• Crystallographic Data Centre. General procedure for the synthesis of spiro[indoline-3,4’-pyridine] derivatives 1a–1p: In an analogous manner to our procedure published in [25], a solution of arylamine (2.0 mmol), methyl propiolate (2.0 mmol) in 5 mL ethanol was stirred at room temperature overnight. Then isatin

Synthesis of spiro[dihydropyridine-oxindoles] via three-component reaction of arylamine, isatin and cyclopentane-1,3-dione

• Yan Sun,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2013, 9, 8–14, doi:10.3762/bjoc.9.2

• -component reactions of arylamine, isatin and cyclopentane-1,3-dione in acetic acid at room temperature. On the other hand the condensation of isatin with two equivalents of cyclopentane-1,3-dione gave 3,3-bis(2-hydroxy-5-oxo-cyclopent-1-enyl)oxindole in high yields. The reaction mechanism and substrate

• scope of this novel reaction is briefly discussed. Keywords: arylamine; cyclopentanedione; isatin; multicomponent reaction; spiro compound; Introduction The spirooxindole is among the most important class of naturally occurring substances, characterized by highly pronounced biological properties, and

• three-component reaction of arylamine, isatin and cyclopentane-1,3-dione. Results and Discussion Recently we found that the four-component reactions of arylamine, acetylenedicarboxylate, isatin and dimedone in acetic acid resulted in the novel functionalized tetrahydrospiro[indoline-3,2’-quinoline

Facile synthesis of functionalized tetrahydroquinolines via domino Povarov reactions of arylamines, methyl propiolate and aromatic aldehydes

• Jing Sun,
• Hong Gao,
• Qun Wu and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2012, 8, 1839–1843, doi:10.3762/bjoc.8.211

• formation of β-enamino ester by the reaction of arylamine with methyl propiolate requires a relative long time [38][39][40][41][42]. Thus, under our previously established reaction conditions a molar excess of p-toludine (4.0 mmol) and methyl propiolate (2.0 mmol) reacted in ethanol at room temperature

• published domino Povarov reaction [45][46][47][48][49]. At first, arylamine adds to methyl propiolate to form the β-enamino ester A. Secondly, excess arylamine reacts with the aromatic aldehyde to form the N-aryl aldimine B in the presence of p-toluenesulfonic acid as catalyst. Thirdly, the Mannich type

• ; the thermodynamically stable trans-isomer is obtained as the final separated product. In the reaction mechanism shown in Scheme 2, arylamine reacts not only with methyl propiolate to form a β-enamino ester, but it also reacts with an aromatic aldehyde to form an imine. We envisioned that two kinds of

A general and facile one-pot process of isothiocyanates from amines under aqueous conditions

• Nan Sun,
• Bin Li,
• Jianping Shao,
• Weimin Mo,
• Baoxiang Hu,
• Zhenlu Shen and
• Xinquan Hu

Beilstein J. Org. Chem. 2012, 8, 61–70, doi:10.3762/bjoc.8.6

• a mixture of amine (20 mmol) and K2CO3 (5.52 g, 40 mmol) in 20 mL of water 1.82 g of CS2 (24 mmol) was added dropwise in a period of 20–30 min at room temperature. After the addition was complete, the mixture was stirred for several hours until complete conversion was determined by HPLC (arylamine

• for the preparation of electron-deficient aryl isothiocyanates A certain amount of CS2 and arylamine (20 mmol) was added to a solution of K2CO3 (5.52 g, 40 mmol) in 20 mL of water and 5 mL of DMF. The mixture was warmed to 40 °C for several hours to a constant conversion based on HPLC determination

Conjugated polymers containing diketopyrrolopyrrole units in the main chain

• Bernd Tieke,
• A. Raman Rabindranath,
• Kai Zhang and
• Yu Zhu

Beilstein J. Org. Chem. 2010, 6, 830–845, doi:10.3762/bjoc.6.92

• arylamine. The bromination of aryl units is important for the subsequent palladium-catalyzed coupling reaction. If the aryl unit is thiophene, direct bromination with N-bromosuccinimide is possible to yield monomer M-3 [16]. For the preparation of conjugated DPP-based polymers, palladium-catalyzed

• arylamine units in the main chain. Due to presence of electron-rich nitrogen atoms it was hoped that donor-acceptor interactions along the main chain would be enhanced and lead to a red-shift of the absorption and emission. Furthermore, the presence of easily oxidizable nitrogen in the main chain should

• arylamine to yield the desired tetraarylated DPP derivative [11]. Using this approach, Zhang and Tieke [48] were able to prepare the two isomeric monomers M-2 and M-4 and their corresponding alternating copolymers P-21 and P-22 containing fluorene as the comonomer unit. While the properties of the two

Suzuki–Miyaura cross-coupling reaction of 1-aryltriazenes with arylboronic acids catalyzed by a recyclable polymer-supported N-heterocyclic carbene–palladium complex catalyst

• Guangming Nan,
• Fang Ren and
• Meiming Luo

Beilstein J. Org. Chem. 2010, 6, No. 70, doi:10.3762/bjoc.6.70

• -AES on IRIS Adv. Pd-leaching was determined by ICP-MS on VG PQ Exceu. General procedure for the preparation of 1-aryltriazenes 1-Aryltriazenes were prepared by a modification of the literature procedure [34]. A solution of arylamine (10 mmol) in concentrated HCl (2 mL) was cooled in an ice bath while

Expedient syntheses of the N-heterocyclic carbene precursor imidazolium salts IPr·HCl, IMes·HCl and IXy·HCl

• Lukas Hintermann

Beilstein J. Org. Chem. 2007, 3, No. 22, doi:10.1186/1860-5397-3-22

• (Scheme 3a). [21] This is one potential side-reaction, but brown colored side-products can also derive from electrophilic aromatic alkylations of arylamine units by iminium salts from formaldehyde or protonated DADs (as in the bakelite reaction). Such side-reactions will be most prominent with DADs from