Synthesis of alpha-tetrasubstituted triazoles by copper-catalyzed silyl deprotection/azide cycloaddition

• Zachary L. Palchak,
• Paula T. Nguyen and
• Catharine H. Larsen

Beilstein J. Org. Chem. 2015, 11, 1425–1433, doi:10.3762/bjoc.11.154

• -deprotection with azide–alkyne cycloaddition, producing hindered triazoles in 6 hours. This tandem reaction was optimal with a copper(II) triflate and sodium ascorbate (NaAsc) as a mild reductant. The outcome that copper(II) triflate provides the highest yields for the one-pot deprotection/click reaction was

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• phenanthridine (Scheme 20) [44]. The synthesis by multicomponent tandem reaction/carbocyclization starts with the formation of a 4-aryl-3-arylethynylisoquinoline from 2-bromobenzaldehyde/tert-butylamine/1,3-diyne. The second (in situ) step is based on the ring closure, either via gold/silver-catalysed

Synthesis of 2-trifluoromethylpyrazolo[5,1-a]isoquinolines via silver triflate-catalyzed or electrophile-mediated one-pot tandem reaction

• Xiaoli Zhou,
• Meiling Liu,
• Puying Luo,
• Yingjun Lai,
• Tangtao Yang and
• Qiuping Ding

Beilstein J. Org. Chem. 2014, 10, 2286–2292, doi:10.3762/bjoc.10.238

• annulation of N’-(2-alkynylbenzylidene)hydrazides followed by an 1,3-dipolar cycloaddition. Results and Discussion Based on Wu’s work on the silver triflate-catalyzed tandem reaction of N’-(2-alkynylbenzylidene)hydrazides with dimethyl acetylenedicarboxylate [28], we started our research by examining the

• -alkynylbenzylidene)hydrazides 1, electrophiles (I2 or ICl), and ethyl 4,4,4-trifluorobut-2-ynoate (2) were carried out under mild conditions. The results are summarized in Table 3. For all cases, this tandem reaction worked well leading to the corresponding iodinated fluorine-containing pyrazolo[5,1-a]isoquinolines

• mode on a Bruker mass spectrometer. General procedure for the silver triflate-catalyzed one-pot tandem reaction of N’-(2-alkynylbenzylidene)hydrazide 1 with ethyl 4,4,4-trifluorobut-2-ynoate 2: A mixture of N’-(2-alkynylbenzylidene)hydrazide 1 (0.30 mmol, 1.0 equiv) and silver triflate (5 mol %) in

A tandem Mannich addition–palladium catalyzed ring-closing route toward 4-substituted-3(2H)-furanones

• Jubi John,
• Eliza Târcoveanu,
• Peter G. Jones and
• Henning Hopf

Beilstein J. Org. Chem. 2014, 10, 1462–1470, doi:10.3762/bjoc.10.150

• . Keywords: aza-prostaglandin analogue; 3(2H)-furanone; Mannich addition; palladium catalysis; tandem reaction; Introduction Organic chemists welcome the introduction of facile tandem protocols because of the advantages of multiple bond formation in one-pot processes, which in turn makes the process

Efficient synthesis of dihydropyrimidinones via a three-component Biginelli-type reaction of urea, alkylaldehyde and arylaldehyde

• Haijun Qu,
• Xuejian Li,
• Fan Mo and
• Xufeng Lin

Beilstein J. Org. Chem. 2013, 9, 2846–2851, doi:10.3762/bjoc.9.320

• Haijun Qu Xuejian Li Fan Mo Xufeng Lin Department of Chemistry, Zhejiang University, Hangzhou 310027, China 10.3762/bjoc.9.320 Abstract A one-pot three-component synthesis of dihydropyrimidinones via a molecular iodine-catalyzed tandem reaction of simple readily available mono-substituted urea

Synthesis of mucin-type O-glycan probes as aminopropyl glycosides

• David Benito-Alifonso,
• Rachel A. Jones,
• Anh-Tuan Tran,
• Hannah Woodward,
• Nichola Smith and
• M. Carmen Galan

Beilstein J. Org. Chem. 2013, 9, 1867–1872, doi:10.3762/bjoc.9.218

• -protected glycosyl acceptor 11 to afford trisaccharide 25 in 78% yield (Scheme 3). With the trisaccharide in hand, we proceeded to globally deprotect the assembled oligomer using a similar tandem reaction sequence as before that involved no column chromatography in between steps. In brief, selective

A construction of 4,4-spirocyclic γ-lactams by tandem radical cyclization with carbon monoxide

• Mitsuhiro Ueda,
• Yoshitaka Uenoyama,
• Nozomi Terasoma,
• Shoko Doi,
• Shoji Kobayashi,
• Ilhyong Ryu and
• John A. Murphy

Beilstein J. Org. Chem. 2013, 9, 1340–1345, doi:10.3762/bjoc.9.151

• tandem reaction of iodoaryl alkenyl azides under radical conditions (Scheme 1) [13][14]. Curran et al. reported the synthesis of spirocyclic pyrrolidinyl dihydroquinolinones by tandem radical cyclization [15][16]. In this study we report a radical cyclization/annulation approach to 4.4-spirocyclic γ

Catalytic asymmetric tandem Friedel–Crafts alkylation/Michael addition reaction for the synthesis of highly functionalized chromans

• Jiahuan Peng and
• Da-Ming Du

Beilstein J. Org. Chem. 2013, 9, 1210–1216, doi:10.3762/bjoc.9.137

• diphenylamine-linked bis(oxazoline)-Zn(OTf)2 complex was investigated. This tandem reaction afforded functionalized chiral chromans in good yields with moderate to high stereoselectivities (up to 95:5 dr, up to 99% ee). Keywords: asymmetric catalysis; bis(oxazoline); chroman; Friedel–Crafts alkylation; tandem

• reaction; Introduction The development of efficient and convenient methods to access complex compounds with multiple stereogenic centers is one of the significant challenges in organic chemistry. Catalytic asymmetric tandem or cascade reactions are powerful tools to afford complex molecules with multiple

Diastereoselective synthesis of nitroso acetals from (S,E)-γ-aminated nitroalkenes via multicomponent [4 + 2]/[3 + 2] cycloadditions promoted by LiCl or LiClO₄

• Leandro Lara de Carvalho,
• Robert Alan Burrow and
• Vera Lúcia Patrocinio Pereira

Beilstein J. Org. Chem. 2013, 9, 838–845, doi:10.3762/bjoc.9.96

• diffraction experiment. Keywords: chiral heterodiene; hetero-Diels–Alder reaction; pyrrolizidin-3-one; solvent effect; tandem reaction; Introduction Conjugated nitroalkenes play an important role in cycloaddition reactions providing useful nitrogenated cycloadducts with varied synthetic applications (Scheme

New simple synthesis of ring-fused 4-alkyl-4H-3,1-benzothiazine-2-thiones: Direct formation from carbon disulfide and (E)-3-(2-aminoaryl)acrylates or (E)-3-(2-aminoaryl)acrylonitriles

• Qiuping Ding,
• Yuqing Lin,
• Guangni Ding,
• Fumin Liao,
• Xiaoyan Sang and
• Yi-Yuan Peng

Beilstein J. Org. Chem. 2013, 9, 460–466, doi:10.3762/bjoc.9.49

• expected to construct 4-alkyl-4H-3,1-benzothiazine-2-thione derivatives through a one-pot base-promoted intermolecular addition/intramolecular Michael addition reaction. Results and Discussion In our initial study, we examined the tandem reaction with various bases and solvents to optimize the reaction

• solvent was evaporated under vacuum, and the residue was isolated by column chromatography with EtOAc/petroleum ether (1/5, v/v) as eluent to yield the desired products 2. For details, see Supporting Information File 1. AgNO3-catalyzed tandem reaction of 2-alkynylbenzenamines with CS2 and their further

Radical zinc-atom-transfer-based carbozincation of haloalkynes with dialkylzincs

• Fabrice Chemla,
• Florian Dulong,
• Franck Ferreira and
• Alejandro Pérez-Luna

Beilstein J. Org. Chem. 2013, 9, 236–245, doi:10.3762/bjoc.9.28

• a formal anti-selective carbozincation reaction. Upon warming, the zinc carbenoid is stereochemically labile and isomerizes to its more stable form. Keywords: carbenoids; carbometallation; carbozincation; radicals; tandem reaction; Introduction The last few years have witnessed a gaining interest

Dipyrazolo[1,5-a:4',3'-c]pyridines – a new heterocyclic system accessed via multicomponent reaction

• Wolfgang Holzer,
• Gytė Vilkauskaitė,
• Eglė Arbačiauskienė and
• Algirdas Šačkus

Beilstein J. Org. Chem. 2012, 8, 2223–2229, doi:10.3762/bjoc.8.251

• synthesis of H-pyrazolo[5,1-a]isoquinolines by a one-pot tandem reaction of 2-alkynylbenzaldehydes, sulfonohydrazide, and ketones or aldehydes [27]. In our case, application of pyrazolecarbaldehydes 1 should enable access to the desired dipyrazolo[1,5-a:4',3'-c]pyridines 5. In order to test the reaction

• base would lead to various dipyrazolo[1,5-a:4',3'-c]pyridines 5. Thus, after these results, we decided to explore the one-pot tandem reaction with various 5-alkynylpyrazole-4-carbaldehydes 1, p-toluenesulfonyl hydrazide and butyraldehyde (4a). As alkynyl functions, phenylethynyl (1a,b), 3

• simple and nonlaborious method to access dipyrazolo[1,5-a:4',3'-c]pyridines from easily obtainable 5-alkynyl-1-phenyl-1H-pyrazole-4-carbaldehydes through a silver triflate catalyzed one-pot tandem reaction with p-toluenesulfonyl hydrazide and an appropriate aldehyde or ketone. Moreover, the novel

Reactions of salicylaldehyde and enolates or their equivalents: versatile synthetic routes to chromane derivatives

• Ishmael B. Masesane and
• Zelalem Yibralign Desta

Beilstein J. Org. Chem. 2012, 8, 2166–2175, doi:10.3762/bjoc.8.244

• sieves have the advantage that they are recyclable. Chromane derivatives from the reaction of salicylaldehyde and enolates derived from α,β-unsaturated compounds The tandem reaction of salicylaldehyde and α,β-unsaturated compounds has proved to be a reliable route to chromane derivatives. In general

• reported the K2CO3-mediated tandem reaction of salicylaldehyde derivatives of type 43 and α,β-unsaturated ester 44 in the synthesis of 2,2-dimethylchromene 45 in moderate yields (Scheme 17) [34]. The dehydration reaction in this case was accompanied by decarboxylation. The best yields were achieved when

• methoxy-, methyl-, chloro-, bromo- and phenyl-substituted salicylaldehydes were used as reagents. The nitro-, hydroxy-, ethoxy- and acetyl-substituted salicylaldehydes on the other hand gave poor yields or no products at all. Related reactions involving a K2CO3-mediated tandem reaction of salicylaldehyde

Organocatalytic cascade aza-Michael/hemiacetal reaction between disubstituted hydrazines and α,β-unsaturated aldehydes: Highly diastereo- and enantioselective synthesis of pyrazolidine derivatives

• Zhi-Cong Geng,
• Jian Chen,
• Ning Li,
• Xiao-Fei Huang,
• Yong Zhang,
• Ya-Wen Zhang and
• Xing-Wang Wang

Beilstein J. Org. Chem. 2012, 8, 1710–1720, doi:10.3762/bjoc.8.195

• group, the stereochemical induction was very poor (Table 3, entry 3). MacMillan’s catalyst 1j was proven to be inefficient for this transformation as only 13% ee was obtained (Table 3, entry 4). Subsequently, three diarylprolinol silyl ether catalysts 1m–o were investigated for this tandem reaction [77

Organocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines

• Chittaranjan Bhanja,
• Satyaban Jena,
• Sabita Nayak and
• Seetaram Mohapatra

Beilstein J. Org. Chem. 2012, 8, 1668–1694, doi:10.3762/bjoc.8.191

• , Córdova et al. [42][43] and subsequently Wang et al. [44] independently reported similar oxa-Michael/aldol reactions by means of the same iminium-ion activation strategies but with improved yields and enantioselectivities. Córdova et al. reported the tandem reaction of salicylaldehydes 1 and α,β

• sieves (4 Å) in the reaction (Scheme 2). Wang et al. [44] investigated the same tandem reaction of salicylaldehydes 1 and α,β-unsaturated aldehydes 2 employing TES-protected diphenylprolinol Ie as organocatalyst with high catalyst loading (30 mol %). With benzoic acid as cocatalyst and dichloroethane as

• -Michael addition followed by aza-Baylis–Hillman reaction by means of an iminium-allenamine activation strategy. Later on, the same authors [49] in 2011 reported a similar tandem reaction (abnormal Baylis–Hillman) between 2-alkynals 5 and salicylaldehyde derivatives 1 catalyzed by proline derivatives

Catalyst-free and solvent-free Michael addition of 1,3-dicarbonyl compounds to nitroalkenes by a grinding method

• Zong-Bo Xie,
• Na Wang,
• Ming-Yu Wu,
• Ting He,
• Zhang-Gao Le and
• Xiao-Qi Yu

Beilstein J. Org. Chem. 2012, 8, 534–538, doi:10.3762/bjoc.8.61

• environmentally hazardous residues and undesirable byproducts [25][26][27][28][29][30]. As one part of our continuing efforts toward the development of green synthesis methods for Michael additions of nitroalkenes, we have previously reported an enzymatic tandem reaction to form 5-hydroxyimino-4,5-dihydrofurans

• [22], a transition-metal-free process for the synthesis of substituted dihydrofurans [23] and a catalyst-free tandem reaction for the synthesis of 5-hydroxy-1,5-dihydro-2H-pyrrol-2-ones in aqueous medium [24]. Recently, when carrying out the reaction of β-nitrostyrene with 1,3-cyclopentanedione under

Synthesis of fused tricyclic amines unsubstituted at the ring-junction positions by a cascade condensation, cyclization, cycloaddition then decarbonylation strategy

• Iain Coldham,
• Adam J. M. Burrell,
• Hélène D. S. Guerrand,
• Luke Watson,
• Nathaniel G. Martin and
• Niall Oram

Beilstein J. Org. Chem. 2012, 8, 107–111, doi:10.3762/bjoc.8.11

• Company, Erl Wood Manor, Windlesham, Surrey GU20 6PH, United Kingdom 10.3762/bjoc.8.11 Abstract Heating aldehydes that contain a protected hydroxymethyl group, a tethered alkyl chloride and a tethered alkenyl group at the α-position of the aldehyde with an amine sets up a cascade (tandem) reaction

Manganese dioxide mediated one-pot synthesis of methyl 9H-pyrido[3,4-b]indole-1-carboxylate: Concise synthesis of alangiobussinine

• Jessica Baiget,
• Sabin Llona-Minguez,
• Stuart Lang,
• Simon P. MacKay,
• Colin J. Suckling and
• Oliver B. Sutcliffe

Beilstein J. Org. Chem. 2011, 7, 1407–1411, doi:10.3762/bjoc.7.164

• process for the preparation of methyl 9H-pyrido[3,4-b]indole-1-carboxylate has subsequently been used as the key step in the synthesis of alangiobussinine and a closely related analogue. Keywords: alkaloid synthesis; carboline; heterocycle; oxidation; tandem reaction; Introduction Carbolines are an

Amines as key building blocks in Pd-assisted multicomponent processes

• Didier Bouyssi,
• Nuno Monteiro and
• Geneviève Balme

Beilstein J. Org. Chem. 2011, 7, 1387–1406, doi:10.3762/bjoc.7.163

• -arylation and intramolecular N-arylation (Scheme 29). The palladium-mediated amination reaction coupled with a nitrogen–carbon bond-forming reaction was also used for the stereoselective synthesis of N-aryl-2-benzylpyrrolidines 71 starting from linear 4-pentenylamine and its derivatives [38]. In this tandem

• reaction, two different aryl bromides are sequentially added to the primary aliphatic amine in the presence of a palladium(0) catalyst. The first selective, Pd-catalyzed mono-N-arylation leading to the corresponding γ-(N-arylamino)alkenes 69 is followed by a carboamination reaction, developed by the same

Recent advances in the gold-catalyzed additions to C–C multiple bonds

• He Huang,
• Yu Zhou and
• Hong Liu

Beilstein J. Org. Chem. 2011, 7, 897–936, doi:10.3762/bjoc.7.103

• 2008 to the present. Keywords: asymmetric addition; catalysis; gold; C−C multiple bonds; tandem reaction; Review 1 Introduction Gold-catalyzed reactions have emerged as a powerful synthetic tool in modern organic synthesis. This past decade has been the boom time for homogeneous gold catalysis, which

• multi-component tandem reaction that involved novel direct alkyne 279–amine 280–glyoxylic acid (278) coupling, intramolecular cyclization of α-N-substituted β-alkynoic acid, and subsequent reaction (Scheme 49) [147]. An intermolecular hetero-dehydro-Diels–Alder reaction between captodative 1,3-dien-5

• substituted naphthalenes 296 [151]. This cascade reaction involves a tandem sequence of 1,3- and 1,2-migration of two different migrating groups. Jin and Yamamoto prepared the fused tri- and tetracyclic enones 298 through an efficient gold(III)-catalyzed tandem reaction, heteroenyne metathesis, and Nazarov

Nano copper oxide catalyzed synthesis of symmetrical diaryl sulfides under ligand free conditions

• K. Harsha Vardhan Reddy,
• V. Prakash Reddy,
• A. Ashwan Kumar,
• G. Kranthi and
• Y.V.D. Nageswar

Beilstein J. Org. Chem. 2011, 7, 886–891, doi:10.3762/bjoc.7.101

• , bases, solvents, and temperature (Table 1). First, several copper catalysts were screened (Table 1), and CuO was found to be promising for this tandem reaction (Table 1, entry 5). Amongst various bases screened, Cs2CO3 and KOH afforded the symmetrical aryl sulfides in excellent yields (Table 1, entries

Solvent- and ligand-induced switch of selectivity in gold(I)-catalyzed tandem reactions of 3-propargylindoles

• Estela Álvarez,
• Delia Miguel,
• Patricia García-García,
• Manuel A. Fernández-Rodríguez,
• Félix Rodríguez and
• Roberto Sanz

Beilstein J. Org. Chem. 2011, 7, 786–793, doi:10.3762/bjoc.7.89

• Organometálica “Enrique Moles”, Universidad de Oviedo, C/Julián Clavería 8, 33006 Oviedo, Spain 10.3762/bjoc.7.89 Abstract The selectivity of our previously described gold-catalyzed tandem reaction, 1,2-indole migration followed by aura-iso-Nazarov cyclization, of 3-propargylindoles bearing (hetero)aromatic

• that show that the reactivity and selectivity of reactions catalyzed by gold complexes can be appropriately tuned [21][22][23][24][25][26][27], we thought that it should be possible to reverse the selectivity of our tandem reaction in favor of the iso-Nazarov pathway, to obtain compounds 4 by a proper

Sequential Au(I)-catalyzed reaction of water with o-acetylenyl-substituted phenyldiazoacetates

• Lei Zhou,
• Yizhou Liu,
• Yan Zhang and
• Jianbo Wang

Beilstein J. Org. Chem. 2011, 7, 631–637, doi:10.3762/bjoc.7.74

• extend this reaction by replacing the amine component with water, and we expected that similar tandem reaction would occur. Copper is a good catalyst for the decomposition of diazo compounds and the subsequent insertion of water. However, we have found that it is not a suitable catalyst for the alcohol

Palladium-catalyzed formation of oxazolidinones from biscarbamates: a mechanistic study

• Benan Kilbas and
• Metin Balci

Beilstein J. Org. Chem. 2011, 7, 246–253, doi:10.3762/bjoc.7.33

• starting from cyclic biscarbamate 1 via a palladium-catalyzed reaction, as shown in Scheme 1. The basic catalytic cyclization (Scheme 1) consists of metal–olefin complexation, ionization, substitution, and decomplexation. The tandem reaction sequence has been frequently applied in the synthesis of many

Tandem catalysis of ring-closing metathesis/atom transfer radical reactions with homobimetallic ruthenium–arene complexes

• Yannick Borguet,
• Xavier Sauvage,
• Guillermo Zaragoza,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2010, 6, 1167–1173, doi:10.3762/bjoc.6.133

• catalyst is likely to occur at the high temperature required to promote the ATRC of 2-cyclohexenyl trichloroacetamide 5, we searched for alternative substrates that would allow us to perform the tandem reaction under less drastic conditions. We were guided in this endeavor by Snapper et al. who had shown