Synthesis of 9-O-arylated berberines via copper-catalyzed C_Ar–O coupling reactions

• Qiaoqiao Teng,
• Xinhui Zhu,
• Qianqian Guo,
• Weihua Jiang,
• Jiang Liu and
• Qi Meng

Beilstein J. Org. Chem. 2019, 15, 1575–1580, doi:10.3762/bjoc.15.161

• considerable improvements in terms of biological activity (Scheme 1, BBR structure). Among all lipophilicity-enhancing strategies, C9-O-Me substitution is the most intensively studied one, which is primarily due to its synthetic convenience. The synthesis starts with pyrolysis of BBR under vacuum at high

Mechanochemical Friedel–Crafts acylations

• Mateja Đud,
• Anamarija Briš,
• Iva Jušinski,
• Davor Gracin and
• Davor Margetić

Beilstein J. Org. Chem. 2019, 15, 1313–1320, doi:10.3762/bjoc.15.130

• photodimer would act as 9,10-dihydroanthracene, and 2-acylated product should be regioselectively formed, which could be converted by thermal retrocyclization via flash vacuum pyrolysis (FVP) [50][51] to 23. However, ball milling of 19 with 20 provided 95% conversion of 19 to anthracene, with a small amount

N-doped carbon dots covalently functionalized with pillar[5]arenes for Fe³⁺ sensing

• Jia Gao,
• Ming-Xue Wu,
• Dihua Dai,
• Zhi Cai,
• Yue Wang,
• Wenhui Fang,
• Yan Wang and
• Ying-Wei Yang

Beilstein J. Org. Chem. 2019, 15, 1262–1267, doi:10.3762/bjoc.15.123

• confirming the successful synthesis of CCDs. Thermogravimetric analysis (TGA, Figure 1f) revealed that the weight loss at 200 °C was due to the pyrolysis of the amino and oxygen groups on the surface of CN-dots, and upon reaching the temperature of 500 °C, CN-dots began to decompose and 61 wt % of its weight

Selective benzylic C–H monooxygenation mediated by iodine oxides

• Kelsey B. LaMartina,
• Haley K. Kuck,
• Linda S. Oglesbee,
• Asma Al-Odaini and
• Nicholas C. Boaz

Beilstein J. Org. Chem. 2019, 15, 602–609, doi:10.3762/bjoc.15.55

• oxidation is only a net 2 electron process. Previous research shows that the rate of radical trapping by molecular iodine nears diffusion control, similar to that of diatomic oxygen [68][69][70]. This process of radical trapping was probed through the pyrolysis of tert-butyl 2-(naphthalen-1-yl

• NHPI-iodate system. Pyrolysis of an acyl perester in the presence of molecular iodine. Proposed mechanism for the selective monooxygenation of benzylic C–H bonds. Oxidant optimization for the NHPI-catalyzed monooxidation of n-butylbenzene (1a). Supporting Information Supporting Information File 70

Sigmatropic rearrangements of cyclopropenylcarbinol derivatives. Access to diversely substituted alkylidenecyclopropanes

• Guillaume Ernouf,
• Jean-Louis Brayer,
• Christophe Meyer and
• Janine Cossy

Beilstein J. Org. Chem. 2019, 15, 333–350, doi:10.3762/bjoc.15.29

• -Δ1-pyrazoline [39]) or by pyrolysis of the sodium salt of 3-propionyloxytetramethylcyclobutanone tosyl hydrazone [40]. It is also worth mentioning that completely divergent reactivities have also been reported for cyclopropenylcarbinyl esters in the presence of transition metal catalysts [41][42

A selective removal of the secondary hydroxy group from ortho-dithioacetal-substituted diarylmethanols

• Anna Czarnecka,
• Emilia Kowalska,
• Agnieszka Bodzioch,
• Joanna Skalik,
• Marek Koprowski,
• Krzysztof Owsianik and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2018, 14, 1229–1237, doi:10.3762/bjoc.14.105

• hydrogenolysis or pyrolysis of the corresponding ortho-1,3-dioxolanyl [65] and ortho-hydroxymethyl [66] substituted diarylmethanols, respectively. It is worth mentioning that the reduction of 9 with ZnI2–Na(CN)BH3 caused decomposition of the starting material. The described reduction process involving 1,3

Continuous-flow retro-Diels–Alder reaction: an efficient method for the preparation of pyrimidinone derivatives

• Imane Nekkaa,
• Márta Palkó,
• István M. Mándity and
• Ferenc Fülöp

Beilstein J. Org. Chem. 2018, 14, 318–324, doi:10.3762/bjoc.14.20

• ] syntheses of heterocyclic compounds. The rDA products can be gained, due to a thermal [4 + 2]-cycloreversion, by distillation under reduced pressure [29], boiling in solvent [30][31], and applying microwave irradiation [32][33][34][35] or flash vacuum pyrolysis [35][36]. rDA reactions under mild conditions

From dipivaloylketene to tetraoxaadamantanes

• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2018, 14, 1–10, doi:10.3762/bjoc.14.1

• obtained by flash vacuum pyrolysis of furan-2,3-dione 6 and dimerizes to 1,3-dioxin-4-one 3, which is a stable but reactive ketene. The transannular addition and rearrangement of enols formed by the addition of nucleophiles to the ketene function in 3 generates axially chiral 2,6,9-trioxabicyclo[3.3.1

• , which, upon flash vacuum pyrolysis (FVP) at 350–500 °C at 10−3–10−4 hPa, eliminates a molecule of CO to generate dipivaloylketene (2) in over 90% yield (Scheme 3). Usually, α-oxoketenes are not isolable, but due to the steric hindrance exerted by the pivaloyl groups ketene 2 is kinetically stable at up

Preparation and isolation of isobenzofuran

• Morten K. Peters and
• Rainer Herges

Beilstein J. Org. Chem. 2017, 13, 2659–2662, doi:10.3762/bjoc.13.263

• vacuum pyrolysis and multistep syntheses of the precursors. The alternative way to synthesize IBF (1) is 1,4-elimination of 1,3-dihydro-1-methoxyisobenzofuran (7, DMIBF), which provides access to IBF (1) at ambient temperature [18]. Three methods have been published to prepare 7 (DMIBF). Reduction of

Novel approach to hydroxy-group-containing porous organic polymers from bisphenol A

• Tao Wang,
• Yan-Chao Zhao,
• Li-Min Zhang,
• Yi Cui,
• Chang-Shan Zhang and
• Bao-Hang Han

Beilstein J. Org. Chem. 2017, 13, 2131–2137, doi:10.3762/bjoc.13.211

• noteworthy that when the reaction is conducted between M1 and phenol selected as the substitution of BPA, a new material is obtained with a BET surface area value calculated as 470 m2 g−1 (Supporting Information File 1, Figure S7), which is a indication of the fact that pyrolysis of BPA might result in some

Block copolymers from ionic liquids for the preparation of thin carbonaceous shells

• Sadaf Hanif,
• Bernd Oschmann,
• Dmitri Spetter,
• Muhammad Nawaz Tahir,
• Wolfgang Tremel and
• Rudolf Zentel

Beilstein J. Org. Chem. 2017, 13, 1693–1701, doi:10.3762/bjoc.13.163

• , which are functionalized thereafter with a block of ionic-liquid polymer. Pyrolysis of these polymer functionalized inorganic nanoparticles leads to TiO2 nanoparticles coated with a thin carbonaceous shell. Such materials may, e.g., be interesting as battery materials. Keywords: block copolymer; carbon

• addition, a macroscopic color change of the hybrid material can be observed. As-synthesized TiO2 nanoparticles coated with the block copolymer looks brown due to the bound catechol. However, the color turns black after the pyrolysis (Figure 4d) indicating the presence of carbon material. This was proven by

• the TiO2 nanoparticles with the block copolymer as a ligand on the surface followed by the pyrolysis of the particles resulting in homogenously coated nanoparticles. (b) Synthesis route for the preparation of the block copolymer, beginning from the monomer synthesis to the block copolymer and finally

Mechanochemistry-assisted synthesis of hierarchical porous carbons applied as supercapacitors

• Desirée Leistenschneider,
• Nicolas Jäckel,
• Felix Hippauf,
• Volker Presser and
• Lars Borchardt

Beilstein J. Org. Chem. 2017, 13, 1332–1341, doi:10.3762/bjoc.13.130

• form the desired template [29][30]. A severe disadvantage of both routes is the need of large amounts of solvents, eventually accumulating as waste during the process. Moreover, these approaches require multiple synthesis steps, including template synthesis, calcination, impregnation, pyrolysis, and

• synthesis approach once again [52]. Scanning and transmission electron micrographs indicate that the carbon material exhibits spherically shaped mesopores (Figure 3), corresponding to the removal of TiO2 particles which have been formed during the pyrolysis (Figure 4). The pores are homogenously distributed

• was expected since the porogens have not been removed during this step in the synthesis. The low specific surface area of 298 m2 g−1 for the composite arises from chemical activation processes of volatile functional groups such as carboxylic acids, which form micropores during pyrolysis. After

Fluorescent carbon dots from mono- and polysaccharides: synthesis, properties and applications

• Stephen Hill and
• M. Carmen Galan

Beilstein J. Org. Chem. 2017, 13, 675–693, doi:10.3762/bjoc.13.67

• and polymerisation in the presence of amino groups makes it a cheap and suitable candidate as a molecular precursor for CD synthesis. To that end, Liu et al. demonstrated in 2011 that the microwave-assisted pyrolysis of glycerol in the presence of TTDDA afforded blue-emissive CDs with a QY of 12

Synthesis of 1-indanones with a broad range of biological activity

• Marika Turek,
• Dorota Szczęsna,
• Marek Koprowski and
• Piotr Bałczewski

Beilstein J. Org. Chem. 2017, 13, 451–494, doi:10.3762/bjoc.13.48

• phenylselenyl-substituted cyclopentenone 269 was less effective and gave 1-indanone 265 in 28% yield only (Scheme 75) [102]. Another example of this reaction catalyzed by a Lewis acid has also been reported [104]. The flash vacuum pyrolysis has been applied for aromatization of 271 to afford 1-indanone 272 in

A new paradigm for designing ring construction strategies for green organic synthesis: implications for the discovery of multicomponent reactions to build molecules containing a single ring

• John Andraos

Beilstein J. Org. Chem. 2016, 12, 2420–2442, doi:10.3762/bjoc.12.236

• cyclohexenone, followed by hydrogenation is 100% atom economical yielding no byproducts. The next best route with an 86% atom economy is the Diels–Alder addition of ketene, generated by pyrolysis of acetone, to 1,3-butadiene to give cyclohex-3-enone, which upon hydrogenation yields cyclohexanone. The only

Synthesis of 2,1-benzisoxazole-3(1H)-ones by base-mediated photochemical N–O bond-forming cyclization of 2-azidobenzoic acids

• Daria Yu. Dzhons and
• Andrei V. Budruev

Beilstein J. Org. Chem. 2016, 12, 874–881, doi:10.3762/bjoc.12.86

• pericyclic mechanism for the formation of heterocyclic compounds in the pyrolysis of aryl azides with unsaturated ortho-substituents. A possible reaction mechanism for the photochemical formation of 2 (Scheme 1, path: 1 → A → 2) based on the report by Platz et al. [54] includes the benzofuroxan formation by

Recent advances in metathesis-derived polymers containing transition metals in the side chain

• Ileana Dragutan,
• Valerian Dragutan,
• Bogdan C. Simionescu,
• Albert Demonceau and
• Helmut Fischer

Beilstein J. Org. Chem. 2015, 11, 2747–2762, doi:10.3762/bjoc.11.296

• = BPh4 or Cl). Self-assembly of these block copolymers into core–shell spherical micelles was successfully conducted and, by UV/ozonolysis or thermal pyrolysis generating antiferromagnetic CoO species, some of these micelles could be converted into inorganic nanoparticles. With the aim at extending the

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

Hybrid macrocycle formation and spiro annulation on cis-syn-cis-tricyclo[6.3.0.0^2,6]undeca-3,11-dione and its congeners via ring-closing metathesis

• Sambasivarao Kotha,
• Ajay Kumar Chinnam and
• Rashid Ali

Beilstein J. Org. Chem. 2015, 11, 1123–1128, doi:10.3762/bjoc.11.126

• ]. Also, based on Fischer indolization and ring-closing metathesis (RCM), we have developed a new strategy to indole-based propellane derivatives [57]. Here, the tricyclic dione 2 required was prepared starting with the Cookson’s dione 4 in two steps involving flash vacuum pyrolysis (FVP) and

The preparation of new functionalized [2.2]paracyclophane derivatives with N-containing functional groups

• Henning Hopf,
• Swaminathan Vijay Narayanan and
• Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 437–445, doi:10.3762/bjoc.11.50

• benzene rings [11][12]. These paracyclophane derivatives are of interest as substrates for the preparation of highly and/or perfluorinated parylene derivatives, the polymer obtained by flash vacuum pyrolysis of the respective paracyclophane precursors. Among the highly alkyl-substituted [2.2

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

• pyrolysis of the condensation product of benzaldehyde and aniline [6]. The reaction conditions were improved by Morgan and Walls, based on a reaction including a cyclization of phenanthridine by dehydrative ring-closure with phosphorus oxychloride in boiling nitrobenzene [7]. Over the 20th century this

Expedient synthesis of 1,6-anhydro-α-D-galactofuranose, a useful intermediate for glycobiological tools

• Luciana Baldoni and
• Carla Marino

Beilstein J. Org. Chem. 2014, 10, 1651–1656, doi:10.3762/bjoc.10.172

• starts from a galactofuranose (D-Galf) template conveniently derivatized. Pioneer procedures for the synthesis of 2 involved the pyrolysis of D-Gal under reduced pressure [11][12] and the acid treatment under heating [13], with the subsequent tedious separation from several byproducts, including the

Site-selective covalent functionalization at interior carbon atoms and on the rim of circumtrindene, a C₃₆H₁₂ open geodesic polyarene

• Hee Yeon Cho,
• Ronald B. M. Ansems and
• Lawrence T. Scott

Beilstein J. Org. Chem. 2014, 10, 956–968, doi:10.3762/bjoc.10.94

• the authors’, have been particularly successful in synthesizing geodesic polyarenes using flash vacuum pyrolysis (FVP) [6]. The FVP method involves slow sublimation of a starting material under vacuum, rapid passage of the gas-phase molecules through a hot zone, and subsequent capture of the products

• circumtrindene (6), one of the most highly-curved fullerene fragments known, comprising 60% of the C60 ball. Results and Discussion Synthesis and properties of circumtrindene (6) In 1996, our laboratory reported that the C36H12 bowl circumtrindene (6) could be obtained by flash vacuum pyrolysis of decacyclene

Recent applications of the divinylcyclopropane–cycloheptadiene rearrangement in organic synthesis

• Sebastian Krüger and
• Tanja Gaich

Beilstein J. Org. Chem. 2014, 10, 163–193, doi:10.3762/bjoc.10.14

• detected in the human body after cocaine consumption. It can be degradatively accessed from cocaine through pyrolysis, cocaine congeners can be prepared via conjugate addition afterwards [113][114]. Boc-protected pyrrole 127 was subjected to rhodium-catalyzed cyclopropanation with vinyldiazo compound 128

An overview of the synthetic routes to the best selling drugs containing 6-membered heterocycles

• Marcus Baumann and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2013, 9, 2265–2319, doi:10.3762/bjoc.9.265

• sequence via the corresponding 2-pyrone (e.g. Scheme 9), which is converted to the 2-pyridone through an exchange with ammonia or an equivalent nitrogen source (NH4X; X = Cl, Br, I, OAc, OH). However, more conveniently the 2-pyrone precursor can be generated via the vacuum pyrolysis of coumalic acid (1.56