Azirinium ylides from α-diazoketones and 2H-azirines on the route to 2H-1,4-oxazines: three-membered ring opening vs 1,5-cyclization

• Nikolai V. Rostovskii,
• Mikhail S. Novikov,
• Alexander F. Khlebnikov,
• Galina L. Starova and
• Margarita S. Avdontseva

Beilstein J. Org. Chem. 2015, 11, 302–312, doi:10.3762/bjoc.11.35

• generated by thermolysis of 2-diazo-1,3-diketones [12] or 5-arylfuran-2,3-diones [13]. Therefore, the presence of compounds 8f,g among the reaction products provides evidence for the formation of some amounts of acetyl(methyl)ketene (12) under the reaction conditions, which, in turn, gives us insight to the

Organic chemistry on surfaces: Direct cyclopropanation by dihalocarbene addition to vinyl terminated self-assembled monolayers (SAMs)

• Malgorzata Adamkiewicz,
• David O’Hagan and
• Georg Hähner

Beilstein J. Org. Chem. 2014, 10, 2897–2902, doi:10.3762/bjoc.10.307

• of vinyl-terminated SAMs has been demonstrated, e.g., through surface modification of radicals generated by C–O bond thermolysis [17] and in a more controlled sense via olefin cross metathesis/enyne metathesis [18] of mixed vinyl and acetylenyl-terminated SAMs followed by Diels–Alder modifications of

Photo, thermal and chemical degradation of riboflavin

• Muhammad Ali Sheraz,
• Sadia Hafeez Kazi,
• Sofia Ahmed,
• Zubair Anwar and
• Iqbal Ahmad

Beilstein J. Org. Chem. 2014, 10, 1999–2012, doi:10.3762/bjoc.10.208

• approximately 15 to 42% [162]. In an another study, when soymilk was heated at 90–140 °C for 6 hours, the thermolysis of RF was found to follow first-order kinetics with the rate constants of 7.05 × 10−4, 4.26 × 10−3 and 2.12 × 10−2 min−1 at 90, 120 and 140 °C, respectively [159]. However, RF is thermally more

Isoxazolium N-ylides and 1-oxa-5-azahexa-1,3,5-trienes on the way from isoxazoles to 2H-1,3-oxazines

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Yelizaveta G. Gorbunova,
• Ekaterina E. Galenko,
• Kirill I. Mikhailov,
• Viktoriia V. Pakalnis and
• Margarita S. Avdontceva

Beilstein J. Org. Chem. 2014, 10, 1896–1905, doi:10.3762/bjoc.10.197

• thermolysis of diazo compounds without a catalyst in inert solvents with high boiling points, such as trifluoromethylbenzene. These conditions were attempted for the preparation of oxazines from isoxazole 1a and diazo compounds 2a–c (Table 1, entries 1–5). The use of a higher boiling-point solvent may also be

Macrocyclic bis(ureas) as ligands for anion complexation

• Claudia Kretschmer,
• Gertrud Dittmann and
• Johannes Beck

Beilstein J. Org. Chem. 2014, 10, 1834–1839, doi:10.3762/bjoc.10.193

• essentially planar molecules (see Supporting Information File 1, Figure S8). Indoloquinolinones can be synthesized by multistep procedures from suitable precursors [12][13][14]. Using thermolysis for the synthesis of indoloquinolines has already been reported. Cyclization of aminophenyl substituted tolane

Domino reactions of 2H-azirines with acylketenes from furan-2,3-diones: Competition between the formation of ortho-fused and bridged heterocyclic systems

• Alexander F. Khlebnikov,
• Mikhail S. Novikov,
• Viktoriia V. Pakalnis,
• Roman O. Iakovenko and
• Dmitry S. Yufit

Beilstein J. Org. Chem. 2014, 10, 784–793, doi:10.3762/bjoc.10.74

• 10.3762/bjoc.10.74 Abstract 3-Aryl-2H-azirines react with acylketenes, generated by thermolysis of 5-arylfuran-2,3-diones, to give bridged 5,7-dioxa-1-azabicyclo[4.4.1]undeca-3,8-diene-2,10-diones and/or ortho-fused 6,6a,12,12a-tetrahydrobis[1,3]oxazino[3,2-a:3′,2′-d]pyrazine-4,10-diones. The latter

• give only 1:2 adducts 3. These were easily isolated from the reaction mixtures by crystallization. In reactions of 1a with 2b, 1b with 2b, and 1c with 2a only 2:2 adducts 4 and 5 are formed and were isolated by chromatography. Thermolysis of furandione 1c in the presence of azirine 2b led to tarring

• acylketenes, generated by thermolysis of 5-arylfuran-2,3-diones 1, to give 5,7-dioxa-1-azabicyclo[4.4.1]undeca-3,8-diene-2,10-diones 3 and/or cis- and trans-6,6a,12,12a-tetrahydrobis[1,3]oxazino[3,2-a:3′,2′-d]pyrazine-4,10-diones 4 and 5. The latter compounds are the products of coupling of two molecules of

Thermodynamically stable [4 + 2] cycloadducts of lanthanum-encapsulated endohedral metallofullerenes

• Yuta Takano,
• Yuki Nagashima,
• M. Ángeles Herranz,
• Nazario Martín and
• Takeshi Akasaka

Beilstein J. Org. Chem. 2014, 10, 714–721, doi:10.3762/bjoc.10.65

• precursors to afford [4 + 2] cycloadducts of fullerenes, the sultine 4,5-benzo-3,6-dihydro-1,2-oxathiin 2-oxide and its derivatives are useful to afford thermodynamically stable compounds because thermolysis of sultine affords highly reactive o-quinodimethanes by extrusion of sulfur dioxide without

• Discussion Synthesis and characterization of La2@C80 cycloadducts o-Quinodimethanes 2a and 2b were generated in situ by thermolysis of the corresponding sultines 1a and 1b in toluene at 80 °C (Scheme 1). The highly reactive intermediates are trapped efficiently by La2@C80, which acts as a dienophile to form

Less reactive dipoles of diazodicarbonyl compounds in reaction with cycloaliphatic thioketones – First evidence for the 1,3-oxathiole–thiocarbonyl ylide interconversion

• Valerij A. Nikolaev,
• Alexey V. Ivanov,
• Ludmila L. Rodina and
• Grzegorz Mlostoń

Beilstein J. Org. Chem. 2013, 9, 2751–2761, doi:10.3762/bjoc.9.309

• representatives 2h–i, neither these diazo compounds nor the corresponding acylketenes generated by their thermolysis [18][19] reacted with thioketone 1a (as proved by 1H NMR spectroscopy) (Table 1, entry 6). Irrespective of the reaction temperature (rt or 80 °C), methyl diazoacetoacetate (2с) reacted with

• corresponding 1,3-oxathiole. Upon increasing the reaction temperature, the rate of the [2 + 3]-cycloaddition of the diazodicarbonyl compounds notably increases, but in the case of diazodiketone 2b simultaneous thermolysis followed by the Wolff rearrangement occurs. The in situ formed 2-oxoketene reacts as a

α-Bromodiazoacetamides – a new class of diazo compounds for catalyst-free, ambient temperature intramolecular C–H insertion reactions

• Åsmund Kaupang and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2013, 9, 1407–1413, doi:10.3762/bjoc.9.157

• thermolysis perform intramolecular C–H insertions to produce α-halo-β-lactams. When carried out with α-bromodiazoacetamides bearing cyclic side chains, the thermolysis reaction affords bicyclic α-halo-β-lactams, in some cases in excellent yields, depending on the ring size and substitution pattern of the

• cyclic amide side chains. Keywords: α-halo-β-lactam; diazo; halocarbonylcarbene; halogenation; thermolysis; Introduction Diazocarbonyl compounds are popular precursors for carbonylcarbenes and -carbenoids, the synthetic utility of which is thoroughly established through their successful employment in

• gel with CH2Cl2 (precooled to −15 °C), in order to remove the base and phthalimide. Allowing the solution to warm to ambient temperature effected the thermolysis of the α-bromodiazoacetamides (Scheme 2). Although we have not determined the exact temperature at which the thermolysis takes place, the α

True and masked three-coordinate T-shaped platinum(II) intermediates

• Manuel A. Ortuño,
• Salvador Conejero and
• Agustí Lledós

Beilstein J. Org. Chem. 2013, 9, 1352–1382, doi:10.3762/bjoc.9.153

The synthesis of well-defined poly(vinylbenzyl chloride)-grafted nanoparticles via RAFT polymerization

• John Moraes,
• Kohji Ohno,
• Guillaume Gody,
• Thomas Maschmeyer and
• Sébastien Perrier

Beilstein J. Org. Chem. 2013, 9, 1226–1234, doi:10.3762/bjoc.9.139

• vinylbenzyl chloride (VBC). Characteristics of polymers produced by the AIBN-initiated, PABTC-mediated polymerization of VBC at 60 °C. Supporting Information Supporting Information File 48: Experimental procedures, equations, kinetic plots, SEC data, light scattering data, thermolysis data and TEM images

4-Pyridylnitrene and 2-pyrazinylcarbene

• Curt Wentrup,
• Ales Reisinger and
• David Kvaskoff

Beilstein J. Org. Chem. 2013, 9, 754–760, doi:10.3762/bjoc.9.85

• Curt Wentrup Ales Reisinger David Kvaskoff School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, Qld 4072, Australia 10.3762/bjoc.9.85 Abstract Both flash vacuum thermolysis (FVT) and matrix photolysis generate 2-diazomethylpyrazine (22) from 1,2,3-triazolo[1,5-a

• -diazacyclohepta-1,2,4,6-tetraene (20). Further photolysis causes ring opening to the ketenimine 27. Keywords: carbene–nitrene interconversion; diazepines; flash vacuum thermolysis; matrix photochemistry; nitrile ylides; reactive intermediates; Introduction The carbene–nitrene interconversion exemplified with

• vacuum thermolysis (FVT) conditions cyanocyclopentadiene 6 is formed (Scheme 1). Several other carbene–nitrene rearrangements have been reported [3][4][5]. In addition to the ring expansion (1–2–3), two ring opening reactions have been investigated in recent years. Type I ring opening takes place in

3-Pyridylnitrene, 2- and 4-pyrimidinylcarbenes, 3-quinolylnitrenes, and 4-quinazolinylcarbenes. Interconversion, ring expansion to diazacycloheptatetraenes, ring opening to nitrile ylides, and ring contraction to cyanopyrroles and cyanoindoles

• Curt Wentrup,
• Nguyen Mong Lan,
• Adelheid Lukosch,
• Pawel Bednarek and
• David Kvaskoff

Beilstein J. Org. Chem. 2013, 9, 743–753, doi:10.3762/bjoc.9.84

• Universität Marburg, D-3550 Marburg, Germany 10.3762/bjoc.9.84 Abstract Precursors of 3-pyridylnitrene and 2- and 4-pyrimidinylcarbenes all afford mixtures of 2- and 3-cyanopyrroles on flash vacuum thermolysis, but 3-cyanopyrroles are the first-formed products. 3-Quinolylnitrenes and 4-quinazolinylcarbenes

• either the nitrenes or the diazacycloheptatetraenes to nitrile ylides. Keywords: carbene-nitrene interconversion; diazepines; flash vacuum thermolysis; matrix photochemistry; nitrile ylides; reactive intermediates; Introduction A multitude of rearrangements of heterocyclic nitrenes have been described

• ) under conditions of photolysis in solution or in matrices as well as under flash vacuum thermolysis (FVT) (Scheme 2) [1][7][8][9][10]. The end products under FVT conditions are the 2- and 3-cyanopyrroles 7 and 8 [10][11]. A competing ring-opening of 2-pyridylnitrenes to cyanobutadienylnitrenes can lead

High-spin intermediates of the photolysis of 2,4,6-triazido-3-chloro-5-fluoropyridine

• Sergei V. Chapyshev,
• Denis V. Korchagin,
• Patrik Neuhaus and
• Wolfram Sander

Beilstein J. Org. Chem. 2013, 9, 733–742, doi:10.3762/bjoc.9.83

• spectroscopy; high-spin states; matrix isolation; nitrenes; photolysis; reactive intermediates; Introduction High-spin nitrenes are highly reactive intermediates formed during photolysis or thermolysis of aromatic polyazides. Both these processes are widely used in modern science and technology [1][2][3][4][5

Synthesis of functionalized macrocyclic derivatives of trioxabicyclo[3.3.0]nonadiene

• Sabine Leber,
• Gert Kollenz and
• Curt Wentrup

Beilstein J. Org. Chem. 2012, 8, 738–743, doi:10.3762/bjoc.8.83

• signals for bisdioxine and tetraoxaadamantane units were made in agreement with previously reported data [1][2][3][4][5][6][7][15]. 1,3,5,7-Tetra-tert-butyl-2,6,9-trioxabicyclo[3.3.1]nona-3,7-diene-4,8-dicarbonyl dichloride (3): Flash vacuum thermolysis of 5-tert-butyl-4-pivaloylfuran-2,3-dione generates

Alkoxide-induced ring opening of bicyclic 2-vinylcyclobutanones: A convenient synthesis of 2-vinyl-substituted 3-cycloalkene-1-carboxylic acid esters

• Xiufang Ji,
• Zhiming Li,
• Quanrui Wang and
• Andreas Goeke

Beilstein J. Org. Chem. 2012, 8, 650–657, doi:10.3762/bjoc.8.72

• been extensively investigated [3][4][5][6][7][8][12][13][14]. To achieve the ring opening, many reaction conditions have been investigated, such as acidic conditions, basic conditions, nucleophilic attack, thermolysis, and oxidizing as well as reducing conditions [4][11]. Cohen and Matz described the

Multistep flow synthesis of vinyl azides and their use in the copper-catalyzed Huisgen-type cycloaddition under inductive-heating conditions

• Lukas Kupracz,
• Jan Hartwig,
• Jens Wegner,
• Sascha Ceylan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2011, 7, 1441–1448, doi:10.3762/bjoc.7.168

• , vinyl azides can be converted into the corresponding 2H-azirines by thermolysis or alternatively by photolysis [5]. The highly reactive azirines can further react as dipolarophiles, dienophiles, electrophiles or nucleophiles [6] thereby accessing oxazoles and isoxazoles [7]. In addition, 2H-azirines

Scalable synthesis of (1-cyclopropyl)cyclopropylamine hydrochloride

• Sergei I. Kozhushkov,
• Alexander F. Khlebnikov,
• Rafael R. Kostikov,
• Dmitrii S. Yufit and
• Armin de Meijere

Beilstein J. Org. Chem. 2011, 7, 1003–1006, doi:10.3762/bjoc.7.113

• preparation of 3 was not sufficiently dried, the thermolysis in t-BuOH along with tert-butylcarbamate 3 gave the 1,3-di(bicyclopropyl)urea (5) in up to 50% yield. Compound 5 was isolated as a colorless solid after deprotection of 3 with HCl/Et2O by evaporation of the mother liquor followed by

The arene–alkene photocycloaddition

• Ursula Streit and
• Christian G. Bochet

Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61

• obtained. Thermolysis of the meta photocycloaddition product results in [1,5]-sigmatropic shifts. The shift can either be a shift of a hydrogen [54] or a carbon [59] atom to afford tetrahydropentalenes. There are also radical approaches to the opening of the cyclopropyl ring. Under Birch reaction

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

• sensitized photooxygenation of the cycloheptatriene derivative 5a5b at room temperature resulted exclusively in the formation of the norcarene endoperoxide 6 [14][17]. The exact configuration of the endoperoxide 6 was determined by the single crystal X-ray analysis of the bisepoxide formed by the thermolysis

Reciprocal polyhedra and the Euler relationship: cage hydrocarbons, C_nH_n and closo-boranes [B_xH_x]²⁻

• Michael J. McGlinchey and
• Henning Hopf

Beilstein J. Org. Chem. 2011, 7, 222–233, doi:10.3762/bjoc.7.30

• investigated structurally and spectroscopically, and their reactivity has also been extensively investigated [42][43][44][45]. Furthermore, as shown in Scheme 16, the octastannacubane, 75, and the per-arylated decastannane, 76, a tin analogue of pentaprismane (11) have been prepared by thermolysis of hexakis

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

• -2-one (18). These results prompted us to examine the cascade RCM/decomposition/ATRA/lactonization of substrate 16 into dichloro compound 18 with homobimetallic complex 1 under mild thermolysis conditions. Thus, the substrate and the catalyst precursor (5 mol %) were dissolved in toluene and heated

Synthesis of highly substituted allenylsilanes by alkylidenation of silylketenes

• Stephen P. Marsden and
• Pascal C. Ducept

Beilstein J. Org. Chem. 2005, 1, No. 5, doi:10.1186/1860-5397-1-5

• generalisation of the approach has been the paucity of methods for preparing substituted silylketenes.[18][19] Methods based upon the thermolysis of siloxyalkynes [20] and dehydrohalogenation of substituted α-silyl acid halides [21][22] have not found general application. We recently reported a mild and