Biphenylene-containing polycyclic conjugated compounds

• Cagatay Dengiz

Beilstein J. Org. Chem. 2023, 19, 1895–1911, doi:10.3762/bjoc.19.141

• reaction, followed by a Au(I)-catalyzed [4 + 2] cycloaddition reaction to afford the target substrate 96 and its regioisomer 95 in a 2:1 ratio (Scheme 20). POA 87 was obtained on Au(111) at 610 K after Ullmann-type coupling and aromatic dehydrogenation of compound 96. Apart from these studies, the

Strategies in the synthesis of dibenzo[b,f]heteropines

• David I. H. Maier,
• Barend C. B. Bezuidenhoudt and
• Charlene Marais

Beilstein J. Org. Chem. 2023, 19, 700–718, doi:10.3762/bjoc.19.51

• ) cyclised products. 3.3 Ullmann-type coupling Copper-catalysed Ullmann etherification (Scheme 20) offers an alternative to SNAr and Buchwald–Hartwig etherification. Olivera et al. [61] reported a copper-catalysed Ullmann-type etherification as a key step in the synthesis of their pyrazole-fused dibenzo[b,f

• underwent intramolecular Ullmann-type coupling catalysed by CuBr·DMS to form the fused dihydro[b,f]oxepine ring system in 89% yield, whereafter hydrogenation afforded 105 in almost quantitative yield (Scheme 22). The method is a sequence of 12 steps, the majority of which are to prepare Wittig reagent

• -pot domino Pd-catalyzed Mizoroki–Heck–Buchwald–Hartwig synthesis of dibenzo[b,f]azepines. Dibenzo[b,f]thiapine and -oxepine synthesis via SNAr (thio)etherification, Wittig methylenation and Mizoroki–Heck reaction. A retrosynthetic pathway to dibenzo[b,f]oxepines via Ullmann coupling. Ullmann-type

Combretastatins D series and analogues: from isolation, synthetic challenges and biological activities

• Jorge de Lima Neto and
• Paulo Henrique Menezes

Beilstein J. Org. Chem. 2023, 19, 399–427, doi:10.3762/bjoc.19.31

• 22 and 36 (Scheme 4 and Scheme 6) and possibly an alkyl oxyphosphonium ion should be more stable [36]. Therefore, the authors proposed a synthetic sequence where the double bond was introduced only after the macrolactonization step. The synthetic route was initiated by an Ullmann-type coupling [37

• hydroxybenzaldehyde 80 into the corresponding acetal followed by Ullmann-type coupling with 52, led to the formation of diaryl ether 83. Subsequent Corey–Fuchs reaction [49] and in situ alkylation led to formation of the propargylic alcohol 85. Deprotection of the aldehyde followed by chain elongation through the

• under different conditions [30] did not lead to the desired macrolide 2, but only the formation of the diolide was observed (Scheme 4). Once the first synthetic pathway did not furnish the desired compound, the authors carried out the formation of the macrocycle using an intramolecular Ullmann-type

Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96

• -closing metathesis (RCM), Clauson–Kaas and Ullmann-type coupling reactions as key steps. Moreover, we have also assembled some other interesting heterocyclic systems possessing oxazole, imidazole, benzimidazole, and benzoxazole in the framework of truxene. Additionally, the preliminary photophysical

• properties (absorption and emission) for these versatile systems has been revealed. Keywords: Clauson–Kaas reaction; heterocycles; ring-closing metathesis; truxene; Ullmann-type coupling; Van Leusen reaction; Introduction The two-dimensional phenylene-based π-conjugated star-shaped architectures has

• metathesis, Ullmann-type coupling, Clauson–Kaas, and Van Leusen reactions as crucial transformations. Synthetic Strategy Basically, our endeavor toward the synthesis of truxene-based systems has been rooted in the development of new synthetic methodologies to assemble diverse polycyclic as well as

Attempted synthesis of a meta-metalated calix[4]arene

• Christopher D. Jurisch and
• Gareth E. Arnott

Beilstein J. Org. Chem. 2019, 15, 1996–2002, doi:10.3762/bjoc.15.195

• Ullmann-type coupling to give aryl azide 2, which readily reacted with phenylacetylene in a copper-catalyzed Huisgen 1,3-dipolar cycloaddition to give 1,2,3-triazole 3 (Scheme 1). The formation of the ruthenacycle was then achieved using Albrecht’s method involving regioselective methylation of triazole 3

• monoazidocalix[4]arene 7, whose synthesis was curiously more challenging than anticipated. Monobromocalix[4]arene 6 was first synthesized as the Ullmann-type coupling precursor in four steps using well established literature procedures [19][23][24][25][26]. Unfortunately, the Ullmann-type coupling route used in

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• -catalyzed Ullmann-type coupling reaction has emerged as an effective method, allowing the synthesis of phenols and aryl thiols from aryl halides through C–O and C–S bond formation, respectively [5][6][7]. Very recently, the C–H activation has made revolutionary advances in organic synthesis because it

Tuning of tetrathiafulvalene properties: versatile synthesis of N-arylated monopyrrolotetrathiafulvalenes via Ullmann-type coupling reactions

• Vladimir A. Azov,
• Diana Janott,
• Dirk Schlüter and
• Matthias Zeller

Beilstein J. Org. Chem. 2015, 11, 860–868, doi:10.3762/bjoc.11.96

• ; pyrrolotetrathiafulvalene; Ullmann-type coupling; X-ray crystallography; Introduction For the last four decades tetrathiafulvalenes [1][2] (Figure 1) 1 have been the subject of extensive studies due to their outstanding electron-donating properties and ability to induce reversible electrochemically-induced switching

• -type coupling reaction was employed for the preparation of several N-arylated monopyrrolotetrathiafulvalenes with variable substitution patterns. Spectroscopic and electrochemical properties of the coupling products strongly depend on the electronic nature of the aromatic substituents due to their

• Vladimir A. Azov Diana Janott Dirk Schluter Matthias Zeller Department of Chemistry, University of Bremen, Leobener Str. NW 2C, D-28359 Bremen, Germany One University Plaza, Department of Chemistry, Youngstown State University, Youngstown, OH 44555-3663, USA 10.3762/bjoc.11.96 Abstract An Ullmann

Screening of ligands for the Ullmann synthesis of electron-rich diaryl ethers

• Nicola Otto and
• Till Opatz

Beilstein J. Org. Chem. 2012, 8, 1105–1111, doi:10.3762/bjoc.8.122

• formation; diaryl ethers; nucleophilic aromatic substitution; Ullmann-type coupling; Introduction The diaryl ether linkage is a common structural motif encountered in numerous classes of natural products. Moreover, various diaryl ethers have been shown to possess antibacterial, anti-inflammatory

• -type coupling, which may result in the formation of undesired side products and a loss in catalyst performance. To avoid this complication, the N,N-dimethylated derivative L43 was synthesized and turned out to exhibit an improved catalytic activity compared to L44. Since L1 showed high catalytic

• 8-hydroxyquinoline (L47) (Table 2 and Figure 3). These ligands have been reported to be effective in the Cu-catalyzed diaryl ether synthesis before [21][27][28][29]. A disadvantage of ligands with free amino or hydroxy groups, such as L44, is that they themselves can act as substrates in the Ullmann

Palladium- and copper-mediated N-aryl bond formation reactions for the synthesis of biological active compounds

• Carolin Fischer and
• Burkhard Koenig

Beilstein J. Org. Chem. 2011, 7, 59–74, doi:10.3762/bjoc.7.10

• palladium sources, reactions on a larger scale are possible. Sterically demanding N-nucleophiles, as well as cyclic and aromatic amino compounds, are suitable coupling partners with aryl bromides. In contrast to palladium catalysis, Ullmann-type coupling reactions tolerate atmospheric oxygen. However