Perspectives on push–pull chromophores derived from click-type [2 + 2] cycloaddition–retroelectrocyclization reactions of electron-rich alkynes and electron-deficient alkenes

• Michio Yamada

Beilstein J. Org. Chem. 2024, 20, 125–154, doi:10.3762/bjoc.20.13

Functionalization of imidazole N-oxide: a recent discovery in organic transformations

• Koustav Singha,
• Imran Habib and
• Mossaraf Hossain

Beilstein J. Org. Chem. 2022, 18, 1575–1588, doi:10.3762/bjoc.18.168

• , the breaking of the C–C bond of intermediate 7 led to the generation of the expected final product 4a through retro-one reaction. It was also shown that the side product, 1-benzyl-4,5-dimethyl-1,3-dihydro-2H-imidazol-2-one (8) was formed from 1a through simply thermal rearrangement. Nucleophilic

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• chromatography (HPLC) (methanol/toluene as the eluent) to isolate a reddish-brown powder of methanofullerene 3 in 21% yield (Scheme 4). Similar to photolysis, the thermal rearrangement of kinetic products gives [6,6]-closed isomers that are thermodynamically more stable. After some time, the team of scientists

The preparation and properties of 1,1-difluorocyclopropane derivatives

• Kymbat S. Adekenova,
• Peter B. Wyatt and
• Sergazy M. Adekenov

Beilstein J. Org. Chem. 2021, 17, 245–272, doi:10.3762/bjoc.17.25

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• underwent a thermal rearrangement to generate tricyclic isobenzofurans 313 through the ring-cleavage of the thietanes. It was assumed that the rearrangement was assisted through participation of the oxygen lone-pair electrons [17] (Scheme 57). The silicon-containing phenyl triphenylsilyl thioketone (316

Preparation of 2-phospholene oxides by the isomerization of 3-phospholene oxides

• Péter Bagi,
• Réka Herbay,
• Nikolett Péczka,
• Zoltán Mucsi,
• István Timári and
• György Keglevich

Beilstein J. Org. Chem. 2020, 16, 818–832, doi:10.3762/bjoc.16.75

• -membered ring. As the thermal rearrangement was only feasible under solvent-free conditions, one may assume mechanism B, which involves the formation of phospholene oxide 1 dimers, and the second molecule only assists the rearrangement similarly to mechanism A. However, according to computations, in this

Rearrangements of organic peroxides and related processes

• Ivan A. Yaremenko,
• Vera A. Vil’,
• Dmitry V. Demchuk and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2016, 12, 1647–1748, doi:10.3762/bjoc.12.162

Copper-mediated synthesis of N-alkenyl-α,β-unsaturated nitrones and their conversion to tri- and tetrasubstituted pyridines

• Dimitra Kontokosta,
• Daniel S. Mueller,
• Dong-Liang Mo,
• Wiktoria H. Pace,
• Rachel A. Simpson and
• Laura L. Anderson

Beilstein J. Org. Chem. 2015, 11, 2097–2104, doi:10.3762/bjoc.11.226

• -unsaturated nitrones, which undergo a subsequent thermal rearrangement to the corresponding tri- and tetrasubstituted pyridines. The optimization and scope of these transformations is discussed. Initial mechanistic experiments suggest a reaction pathway involving oxygen transfer followed by cyclization

• -propargylic oximes and undergo similar electrocyclizations to form pyridines (Scheme 2B) [52]. Herein, we show that N-alkenylnitrones 8 can be prepared through a Chan–Lam coupling of α,β-unsaturated oximes 6 and an alkenylboronic acids 7 and that these compounds undergo a novel thermal rearrangement to the

Recent advances in the electrochemical construction of heterocycles

• Robert Francke

Beilstein J. Org. Chem. 2014, 10, 2858–2873, doi:10.3762/bjoc.10.303

• phenols [78][79], they could observe the formation of spiropentacyclic scaffold 76 (Scheme 29) as byproduct of the electrolysis of 2,4-dimethylphenol (72) [80]. Later it turned out that compound 73 (a dehydrotetramer of 72) is the actual electrolysis product, which reacted to 76 via thermal rearrangement

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

• products; total synthesis; vinylcyclopropane–carbaldehyde rearrangement; Introduction The first documented divinylcyclopropane–cycloheptadiene rearrangement dates back to 1960 occuring during studies of Vogel and coworkers [1][2] on the thermal rearrangement of small carbocycles. Although the desired cis

Sequential Diels–Alder/[3,3]-sigmatropic rearrangement reactions of β-nitrostyrene with 3-methyl-1,3-pentadiene

• Peter A. Wade,
• Alma Pipic,
• Matthias Zeller and
• Panagiota Tsetsakos

Beilstein J. Org. Chem. 2013, 9, 2137–2146, doi:10.3762/bjoc.9.251

• to afford 4-nitrocyclohexenes. Cycloadducts derived from the reaction at the higher substituted diene double bond of either diene failed to undergo a thermal rearrangement. Rates and success of the rearrangement are consistent with a concerted mechanism possessing a dipolar transition state. An

• of nitronic esters A variety of O-allyl nitronic esters have previously been shown to undergo a non-catalyzed thermal rearrangement to γ,δ-unsaturated nitro compounds [1]. Nitronic esters 2 and 3 also undergo this rearrangement (Scheme 3). Thus, nitro compound 18 is obtained in 74% yield when a DMF

• products, and model cations. Sn(IV)-catalyzed isomerization of nitronic esters. Thermal rearrangement of nitronic esters 2 and 3. Thermal rearrangement of nitronic esters 21a, 21b and 22b. Thermal reactions of nitronic esters 5, 7, and 26a–d. General transition state for the [3,3]-sigmatropic rearrangement

A reductive coupling strategy towards ripostatin A

• Kristin D. Schleicher and
• Timothy F. Jamison

Beilstein J. Org. Chem. 2013, 9, 1533–1550, doi:10.3762/bjoc.9.175

• . Based on these results, regioisomer formation cannot be excluded. Several aspects of the enyne synthesis and the nickel-catalyzed coupling reaction require further investigation. As 6 does not itself appear to undergo thermal rearrangement, it seems advantageous to convert this compound to the

A new synthetic access to 2-N-(glycosyl)thiosemicarbazides from 3-N-(glycosyl)oxadiazolinethiones and the regioselectivity of the glycosylation of their oxadiazolinethione precursors

• El Sayed H. El Ashry,
• El Sayed H. El Tamany,
• Mohy El Din Abdel Fattah,
• Mohamed R. E. Aly,
• Ahmed T. A. Boraei and
• Axel Duerkop

Beilstein J. Org. Chem. 2013, 9, 135–146, doi:10.3762/bjoc.9.16

• : glycosyloxadiazolinethiones; glycosylsulfanyloxadiazoles; glycosylthiosemicarbazides; thermal rearrangement; X-ray crystallography; Introduction Modified nucleosides are versatile motifs for studying the relationship between the structure and functions of nucleic acids and problems of metabolism, besides their main

• continuation of our previous work [33] in which the synthesis of compounds 5 to 13 and 20 were published in a preliminary manner without the experimental details, this paper introduces more examples for the thermal rearrangement of S-glycosides to the corresponding N-glycosides, which deliver excellent yields

• signals at δc 176.10–177.40 ppm. Anomeric carbons in both types were observed at δ 83.20–84.00 ppm. Thermal rearrangement of the S-glycosides 5–7 under solvent-free and atmospheric conditions afforded the corresponding 3-N-glycosides 8–10. The conversion was achieved in a few minutes with good to

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Rh-Catalyzed rearrangement of vinylcyclopropane to 1,3-diene units attached to N-heterocycles

• Franca M. Cordero,
• Carolina Vurchio,
• Stefano Cicchi,
• Armin de Meijere and
• Alberto Brandi

Beilstein J. Org. Chem. 2011, 7, 298–303, doi:10.3762/bjoc.7.39

• domino 1,3-dipolar cycloaddition/thermal rearrangement sequence, were converted by Wittig methylenation to the corresponding vinylcyclopropanes (VCPs), which underwent rearrangement to 1,3-dienes in the presence of the Wilkinson Rh(I) complex under microwave heating. The previously unexplored Rh(I

• shift in the cyclopropanated 1,6-diradical intermediate, which in this case is probably facilitated by the enhanced mobility of the benzylic hydrogen and by the formation of the conjugationally stabilized imine 9 [11]. The 1,3-dipolar cycloaddition/thermal rearrangement domino reaction of BCP (2) with

• File 1 for full experimental data). The two diastereomeric indolizidinones anti-12 and syn-12 are formed by the thermal rearrangement of the cycloadducts anti-(3-t-BuO)-11 and syn-(3-t-BuO)-11, respectively. Wittig olefination of ketones 8, anti-12 and 16 [43] with MePPh3Br/t-BuOK in THF at room

Thermal rearrangement of tert-butylsulfinamide

• Veera Reddy Arava,
• Laxminarasimhulu Gorentla and
• Pramod Kumar Dubey

Beilstein J. Org. Chem. 2011, 7, 9–12, doi:10.3762/bjoc.7.2

• above room temperature, and in chlorinated solvents they undergo rearrangement to form the more stable N-(tert-butylthio)-tert-butylsulfonamide. Keywords: chlorinated solvents; N-(tert-butylthio)-tert-butylsulfonamide; tert-butylsulfinamide; thermal rearrangement; Introduction Over the past decade, an

• TEMPO a radical initiator (entries 22 and 23) or by a radical inhibitor 2,6-di-tert-butylphenol (entry 24). When the reagent 1 alone was subjected to thermal rearrangement (entry 1), complete consumption of starting material was observed. Only 27% product was isolated and 73% of the material was lost by

Synthesis of bis(3-{[2-(allyloxy)ethoxy]methyl}-2,4,6-trimethylbenzoyl)(phenyl)phosphine oxide – a tailor-made photoinitiator for dental adhesives

• Norbert Moszner,
• Iris Lamparth,
• Jörg Angermann,
• Urs Karl Fischer,
• Frank Zeuner,
• Thorsten Bock,
• Robert Liska and
• Volker Rheinberger

Beilstein J. Org. Chem. 2010, 6, No. 26, doi:10.3762/bjoc.6.26

• showed an unexpected low thermal stability. Its thermal rearrangement at 180 °C resulted in a fast formation of 3-(chloromethyl)-2,4,6-trimethylbenzoic acid 2-(allyloxy)ethyl ester. In the third step, the acid chloride was reacted with phenylphosphine dilithium with the formation of bis(3-{[2-(allyloxy

• rapidly on heating at 180 °C for 4 h. Obviously, this reaction is a thermal rearrangement because an exchange of chlorine with the 2-(allyloxy)ethoxy group took place as a result of heating (Scheme 3). In this context, it should be noted that we also found the exchange of chlorine in the cases of both the

Mitomycins syntheses: a recent update

• Jean-Christophe Andrez

Beilstein J. Org. Chem. 2009, 5, No. 33, doi:10.3762/bjoc.5.33

• -butadienes Reinhoudt illustrated the stereoselective thermal rearrangement of 1-(1-pyrrolidinyl)-1,3-butadienes for the synthesis of mitosane analogs [103][104][105]. They proposed that the transformation proceeded through two consecutive pericyclic reactions (Scheme 38). Starting from compound 131, a [1][6

Trapping evidence for the thermal cyclization of di-(o-acetylphenyl)acetylene to 3,3'-dimethyl- 1,1'-biisobenzofuran

• Charles P. Casey,
• Neil A. Strotman and
• Ilia A. Guzei

Beilstein J. Org. Chem. 2005, 1, No. 18, doi:10.1186/1860-5397-1-18

• suggested to involve thermal rearrangement of 1 to the intermediate 3,3'-dimethyl-1,1'-biisobenzofuran (A), and subsequent Diels-Alder cycloadditions of two equivalents of DMAD to A. The isolation of trapping products meso-3 and rac-3, which contain complex polycyclic frameworks, provide strong evidence for

• reactions with oxygen, either in the presence or absence of light, to give diketones as the predominant products.[4][5][6][7] The bicyclization process considered for the conversion of 1 to A is analogous to the thermal rearrangement of a 2,6-alkadien-4-yn-1,8-dialdehyde to a bifuran observed by Iyoda[8

• isobenzofuryl carbene complexes. Reagents and conditions: (a) Me3SiC≡CH, Pd(PPh3)4, CuI, Et3N, toluene, 40°C, 22 h, 99 %; (b) KF, MeOH, 91 %; (c) 2'-iodoacetophenone, Pd(PPh3)4, CuI, Et3N, toluene, 40°C, 22 h, 62 %; (d) Cp(CO)2Re(THF), THF, 0→22°C, 5 h Possible thermal bicyclization of 1 to A. Thermal