Palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines

• Geng-Xin Liu,
• Xiao-Ting Jie,
• Ge-Jun Niu,
• Li-Sheng Yang,
• Xing-Lin Li,
• Jian Luo and
• Wen-Hao Hu

Beilstein J. Org. Chem. 2024, 20, 661–671, doi:10.3762/bjoc.20.59

• -light-mediated palladium-catalyzed three-component radical-polar crossover carboamination of 1,3-dienes or allenes with diazo esters and amines, affording unsaturated γ- and ε-amino acid derivatives with diverse structures. In this methodology, the diazo compound readily transforms into a hybrid α-ester

• a highly emerging area of research and exhibit complementary reactivity to those well-developed carbene-mediated MCRs [30][31][32][33][34][35][36][37][38][39][40][41][42]. In the radical-mediated difunctionalization of alkenes, the carbon-centered radical species from a diazo compound can add to

• diverse alkenes followed by a diradical coupling or radical addition process to achieve the difunctionalization (Scheme 1b, middle) [32][33][34][35][36][37]. However, to the best of our knowledge, the methodology involving the addition of a carbon radical from a diazo compound onto the double bond of an

Entry to new spiroheterocycles via tandem Rh(II)-catalyzed O–H insertion/base-promoted cyclization involving diazoarylidene succinimides

• Alexander Yanovich,
• Anastasia Vepreva,
• Ksenia Malkova,
• Grigory Kantin and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2024, 20, 561–569, doi:10.3762/bjoc.20.48

• earlier and the synthetic methodology investigated in this work. An initial example on Rh(II)-catalyzed O–H insertion/base-promoted cyclization involving diazo compound 1a. Tandem Rh2(esp)2-catalyzed O–H insertion/base-promoted cyclization involving DAS 1 and various propiolic acids; PMP = 4-methoxyphenyl

Cycloaddition reactions of heterocyclic azides with 2-cyanoacetamidines as a new route to C,N-diheteroarylcarbamidines

• Pavel S. Silaichev,
• Tetyana V. Beryozkina,
• Vsevolod V. Melekhin,
• Valeriy O. Filimonov,
• Andrey N. Maslivets,
• Vladimir G. Ilkin,
• Wim Dehaen and
• Vasiliy A. Bakulev

Beilstein J. Org. Chem. 2024, 20, 17–24, doi:10.3762/bjoc.20.3

• opening of triazole 6 to form diazo compound anti-7, followed by rotation around the C‒C bond of the amidine group to furnish rotamer syn-7 which then undergoes 1,5-dipolar cyclization to products 3. The second path involves a Dimroth-type cyclization to form products 3′, which however, were not

N-Boc-α-diazo glutarimide as efficient reagent for assembling N-heterocycle-glutarimide diads via Rh(II)-catalyzed N–H insertion reaction

• Grigory Kantin,
• Pavel Golubev,
• Alexander Sapegin,
• Alexander Bunev and
• Dmitry Dar’in

Beilstein J. Org. Chem. 2023, 19, 1841–1848, doi:10.3762/bjoc.19.136

• )-catalyzed N–H insertion reactions involving NH-heterocycles. The proposed method enables the synthesis of multigram quantities of diazo compound 5 rapidly. Furthermore, it can be stored up to several weeks in the refrigerator (5 °C) without any observable alterations. A diverse array of NH-heterocycles with

• tetrazoles, had not been previously utilized in the CRBN ligands design. Catalytic decomposition reactions of diazo compound 5 with NH-heterocycles were conducted in a dry DCM solution using dirhodium espinoate (Rh2(esp)2, 0.06–0.18 mol %). The Rh2(esp)2 catalyst was selected for its excellent versatility

Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control

• Carlee A. Montgomery and
• Graham K. Murphy

Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86

• series of ylide precursors and found that when diazo compound 69 was reacted with 67 (with or without a transition-metal catalyst), no reaction occurred. Conversely, iodonium ylides 31, 70 and 71 all reacted with 67 to produce 68 in 28–81% yield. A significant improvement was realized when an ortho-ether

Pyridine C(sp²)–H bond functionalization under transition-metal and rare earth metal catalysis

• Haritha Sindhe,
• Malladi Mounika Reddy,
• Karthikeyan Rajkumar,
• Akshay Kamble,
• Amardeep Singh,
• Anand Kumar and
• Satyasheel Sharma

Beilstein J. Org. Chem. 2023, 19, 820–863, doi:10.3762/bjoc.19.62

• and the base the initial direct C–H activation of the ylide 12 gives the copper pyridinium ylide 15. The latter reacts with the diazo compound formed through reaction of hydrazone 13 with the base to give the copper–carbene species 16. Then, the intermediate 16 undergoes a Cu–carbene migratory

Access to cyclopropanes with geminal trifluoromethyl and difluoromethylphosphonate groups

• Ita Hajdin,
• Romana Pajkert,
• Mira Keßler,
• Jianlin Han,
• Haibo Mei and
• Gerd-Volker Röschenthaler

Beilstein J. Org. Chem. 2023, 19, 541–549, doi:10.3762/bjoc.19.39

• % yield (Table 1, entry 6). In addition, in a catalyst-free reaction under UV irradiation, no reaction occurred and the starting diazo compound 5 was recovered (Table 1, entry 7). Having identified the optimal catalyst and conditions, we then examined the scope of the cyclopropanation reaction by reacting

• olefins with different aliphatic chains. The total conversion of the diazo compound 5 was achieved after 2.5–3.5 hours of heating and the corresponding cyclopropanes 7a–g were obtained in moderate to good yield (28–53%). The highest yield (53%) as well as the best diastereoselectivity were recorded for

• chromatography were unsuccessful. In addition, alkenes such as allylpentafluorobenzene, diethyl allylmalonate, allylbenzene and ethyl acrylate did not react with 5. Instead, the diazo compound 5 decomposed immediately under the reaction conditions described in Scheme 4. To better understand the mechanism and to

Vicinal ketoesters – key intermediates in the total synthesis of natural products

• Marc Paul Beller and
• Ulrich Koert

Beilstein J. Org. Chem. 2022, 18, 1236–1248, doi:10.3762/bjoc.18.129

• mesoxalic ester amide 102 in a Friedel–Crafts reaction followed by a spontaneous lactamization to give (rac)-cladoniamide G (103). The mesoxalic ester amide 102 was synthesized from malonyl chloride 104 through amidation and Regitz diazotransfer, yielding diazo compound 105. Subsequent oxidation and

Regioselectivity of the S_EAr-based cyclizations and S_EAr-terminated annulations of 3,5-unsubstituted, 4-substituted indoles

• Jonali Das and
• Sajal Kumar Das

Beilstein J. Org. Chem. 2022, 18, 293–302, doi:10.3762/bjoc.18.33

• catalysis diazo compound 30 delivered 3,4-fused tricyclic indole derivative 32 which underwent spontaneous rearrangement to thermodynamically more stable naphthalene derivative 33 upon standing for a few hours. To the best of our knowledge, this is the only report of catalyst-controlled C3 versus C5

Efficient synthesis of ethyl 2-(oxazolin-2-yl)alkanoates via ethoxycarbonylketene-induced electrophilic ring expansion of aziridines

• Yelong Lei and
• Jiaxi Xu

Beilstein J. Org. Chem. 2022, 18, 70–76, doi:10.3762/bjoc.18.6

• -2-yl)alkanamides and 1-(oxazolin-2-yl)alkylphosphonates. Keywords: aziridine; diazooxoester; diazo compound; ketene; oxazoline; ring expansion; Introduction Oxazoline derivatives are an important class of nitrogen and oxygen-containing five-membered unsaturated heterocycles [1] and widely exist in

• [23], 1c,d [24], 1e,g [25], 1f [26], 1h [27] and 1i [28]. Aziridines 2 were prepared according to our previous method [21] and their analytic data are identical to previously reported ones 2a–f [21] and 2g [29]. General procedure for the synthesis of ethyl 2-(oxazol-2-yl)alkanoates 3 Diazo compound 1

[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

• C60 or b) possible formation of both isomers as a result of 1,3-dipolar cycloaddition of the diazo compound to the fullerene, followed by elimination of molecular nitrogen from the pyrazoline intermediate. Second, the rearrangement of [5,6]-open isomers into thermodynamically more stable [6,6]-closed

• methanofullerene in the reaction mixture after the loss of H2 depends on the diazo compound used for the cycloaddition. According to 13C NMR data, the [6,5]-bridged compound 5 has an open transannular bond, while the [6,6]-bridged compound 6 has a closed trans-ring bond. A synthetically interesting building block

• with tosylhydrazone The first publication on the synthesis of methanofullerenes via tosyl derivatives appeared in 1993 [83]. According to the original source, C60 cyclopropanation is assumed to involve a diazo compound preliminarily synthesized from an aldehyde- or ketone-based tosylhydrazone. The

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

All-carbon [3 + 2] cycloaddition in natural product synthesis

• Zhuo Wang and
• Junyang Liu

Beilstein J. Org. Chem. 2020, 16, 3015–3031, doi:10.3762/bjoc.16.251

• triquinane (±)-hirsutene (14) [24] (Scheme 1D). In 2011, the same research group used allenyl diazo compound 38, which was generated from the reaction between aldehyde 37 and p-toluenesulfonehydrazide in the presence of sodium hydride upon heating, to produce diyl 40 [29] (Scheme 2A). The intramolecular

• 2014 and 2017, respectively (Scheme 2B and Scheme 2C). The synthesis of (−)-crinipellin A (15) began with the treatment of hydrazone 42 with sodium hydride under reflux to produce the tetraquinane 46 in 87% yield [30] (Scheme 2B). The authors suggested that the diazo compound 43 formed undergoes an

• ] cycloaddition produces tricycle 36 in the preparation of (±)-hirsutene (14) [24]. (A) An intramolecular trimethylenemethane diyl [3 + 2] cycloaddition with allenyl diazo compound 38 as a key intermediate to give angular-fused triquinane 41 [29]. (B) Synthesis of (−)-crinipellin A (15) [30]. (C) Synthesis of

Photocatalytic trifluoromethoxylation of arenes and heteroarenes in continuous-flow

• Alexander V. Nyuchev,
• Ting Wan,
• Borja Cendón,
• Carlo Sambiagio,
• Job J. C. Struijs,
• Michelle Ho,
• Moisés Gulías,
• Ying Wang and
• Timothy Noël

Beilstein J. Org. Chem. 2020, 16, 1305–1312, doi:10.3762/bjoc.16.111

• recently reported [8][9][11], for example the trifluoromethylation of hydroxyaryls [12][13][14], and the direct introduction of the -OCF3 moiety into an organometallic species [15], a diazo compound [16][17], or an unfunctionalized C–H bond (Scheme 1B). The latter method is particularly interesting

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• this transformation involves the formation of an aryl radical by SET between the diazo compound and the porphyrin in its excited state (Scheme 3). The authors demonstrated that meso-arylated porphyrins can efficiently act by an oxidative quenching. However, issues about why an electron-poor porphyrin

Preparation and in situ use of unstable N-alkyl α-diazo-γ-butyrolactams in Rh^II-catalyzed X–H insertion reactions

• Maria Eremeyeva,
• Daniil Zhukovsky,
• Dmitry Dar’in and
• Mikhail Krasavin

Beilstein J. Org. Chem. 2020, 16, 607–610, doi:10.3762/bjoc.16.55

• immediate addition of the X–H insertion partner and a RhII catalyst to the solution of the diazo compound. The reactions are rapid, albeit moderately yielding. Despite the latter drawback, the range of 1,3-disubstituted 2-pyrrolidones attainable via the intermediate formation of α-diazo-γ-butyrolactams was

Cyclopropanation–ring expansion of 3-chloroindoles with α-halodiazoacetates: novel synthesis of 4-quinolone-3-carboxylic acid and norfloxacin

• Sara Peeters,
• Linn Neerbye Berntsen,
• Pål Rongved and
• Tore Bonge-Hansen

Beilstein J. Org. Chem. 2019, 15, 2156–2160, doi:10.3762/bjoc.15.212

• functionalization [3][4][5][6]. The metal carbene reactions with indoles have been studied for the three types of carbenoids: acceptor–acceptor [7][8][9], mono-acceptor [10] and donor–acceptor carbenoids [11][12][13][14]. Depending on the metal and the diazo compound, the chemo- and regioselectivity in the metal

Reusable and highly enantioselective water-soluble Ru(II)-Amm-Pheox catalyst for intramolecular cyclopropanation of diazo compounds

• Hamada S. A. Mandour,
• Yoko Nakagawa,
• Masaya Tone,
• Hayato Inoue,
• Nansalmaa Otog,
• Ikuhide Fujisawa,
• Soda Chanthamath and
• Seiji Iwasa

Beilstein J. Org. Chem. 2019, 15, 357–363, doi:10.3762/bjoc.15.31

• cyclopropanation using various diazo compounds with Ru(II)-Amm-Pheox Several diazoacetates and diazoacetamides were tested for asymmetric intramolecular cyclopropanation reactions using Ru(II)-Amm-Pheox catalyst (cat. 2) in H2O/ether biphasic medium as shown in Table 1. A diazo compound derived from allyl

• diazoacetate could be cyclopropanated affording the corresponding lactone with low yield and good enantioselectivity (Table 1, entry 1). In case of the diazo compound derived from cinnamyl diazoacetate the corresponding lactone was obtained in high yield with high enantioselectivity (Table 1, entry 2). A

• amide derivatives bearing electron-donating or electron-withdrawing groups at the ortho, meta, or para positions could be converted to the corresponding bicyclic products in excellent yields (up to 99%) and enantioselectivities (up to 98% ee, Scheme 1, 2g−m). A diazo compound with two chlorine

Gold-catalyzed ethylene cyclopropanation

• Silvia G. Rull,
• Andrea Olmos and
• Pedro J. Pérez

Beilstein J. Org. Chem. 2019, 15, 67–71, doi:10.3762/bjoc.15.7

• frequently is avoided upon maintaining a low diazo compound/catalyst ratio, employing slow addition devices to incorporate a solution of the diazo reagent into the reaction mixture containing the olefin and the catalyst. Unfortunately, the use of ethylene as the olefin requires a pressure vessel and thus the

Molecular iodine-catalyzed one-pot multicomponent synthesis of 5-amino-4-(arylselanyl)-1H-pyrazoles

• Camila S. Pires,
• Daniela H. de Oliveira,
• Maria R. B. Pontel,
• Jean C. Kazmierczak,
• Roberta Cargnelutti,
• Diego Alves,
• Raquel G. Jacob and
• Ricardo F. Schumacher

Beilstein J. Org. Chem. 2018, 14, 2789–2798, doi:10.3762/bjoc.14.256

• -(phenylselanyl)-1H-pyrazol-5-amine was submitted to an oxidative dehydrogenative coupling to produce a diazo compound confirmed by X-ray analysis. Keywords: diaryl diselenide; diazo compound; 1H-pyrazole; molecular iodine; multicomponent reaction; Introduction Selenium-containing compounds are of great

Novel photochemical reactions of carbocyclic diazodiketones without elimination of nitrogen – a suitable way to N-hydrazonation of C–H-bonds

• Liudmila L. Rodina,
• Xenia V. Azarova,
• Jury J. Medvedev,
• Dmitrij V. Semenok and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2018, 14, 2250–2258, doi:10.3762/bjoc.14.200

• 4 and 5). The reactions of tricyclic diazodiketone 1c and diazoindandione 1f in the presence of benzophenone as sensitizer proceeded in a similar way to diazo compound 1b under the optimal conditions affording hydrazones 2c,f in yields of 63 and 52%, respectively (Table 1, entries 10 and 13). An

Atom-economical group-transfer reactions with hypervalent iodine compounds

• Andreas Boelke,
• Peter Finkbeiner and
• Boris J. Nachtsheim

Beilstein J. Org. Chem. 2018, 14, 1263–1280, doi:10.3762/bjoc.14.108

• of elemental nitrogen is lost over the course of the reaction. The overall AE is only diminished by the necessity to use two equivalents of the diazo compound (AE = 74% for 43b). Furthermore, an enantioselective version of this oxyalkynylation (for R1 = H) was developed [57]. Employing a chiral

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• benzotropones 11 and 12 (Scheme 14 and Scheme 33) [78]. Diazo compound 76 was prepared from 4,5-benzotropone hydrazone under oxidative conditions. Irradiation of matrix-isolated 7-diazo-7H-benzo[7]annulene (76) afforded a mixture of triplet 7H-benzo[7]annulenylidene (77), 2,3-benzobicyclo[4.1.0]hepta-2,4,6

• ], while the allenic rearrangement product 183 for the carbene 75 was not detected in the photolysis of a diazo compound (Scheme 33) [78]. 2,3-Benzotropone (12) was converted to gem-dichloride 187 to achieve diazirine as carbene precursor (Scheme 33) [77][144]. 3.2.2. Ring-expansion reactions via a tropone

Rh(II)-mediated domino [4 + 1]-annulation of α-cyanothioacetamides using diazoesters: A new entry for the synthesis of multisubstituted thiophenes

• Jury J. Medvedev,
• Ilya V. Efimov,
• Yuri M. Shafran,
• Vitaliy V. Suslonov,
• Vasiliy A. Bakulev and
• Valerij A. Nikolaev

Beilstein J. Org. Chem. 2017, 13, 2569–2576, doi:10.3762/bjoc.13.253

• diazomalonate, which is unusual for Rh(II)-catalyzed reactions of this diazo compound [26]. Application of more active catalysts like dirhodium tetraoctanoate or tetrapivalate makes it possible to reduce the reaction time at reflux in benzene to 2 h (Table 1, entries 3 and 4). In the case of dirhodium

Hydrolysis, polarity, and conformational impact of C-terminal partially fluorinated ethyl esters in peptide models

• Vladimir Kubyshkin and
• Nediljko Budisa

Beilstein J. Org. Chem. 2017, 13, 2442–2457, doi:10.3762/bjoc.13.241

• added to a solution of N-acetylproline in water (2.5 mL). The mixture was stirred at room temperature for 16 hours. Then, trifluoroacetic acid (0.1 mL) was added, and the mixture was stirred for an additional hour to quench residual diazo compound. The solution was then freeze-dried. Purification of the

• crude material on a silica gel column afforded 30 mg of 4 as a clear oil (yield 20%). When the diazo compound was generated in an acetonitrile/water (1:1) mixture (4.5 mL), no heating was applied, and N-acetylproline was added to the yellowish mixture 5 min after mixing the amine with the nitrite. From