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Search for "alkenes" in Full Text gives 543 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Synthesis of tetrahydrofuro[3,2-c]pyridines via Pictet–Spengler reaction

  • Elena Y. Mendogralo and
  • Maxim G. Uchuskin

Beilstein J. Org. Chem. 2023, 19, 991–997, doi:10.3762/bjoc.19.74

Graphical Abstract
  • the use of 3-substituted furans. For example, the intramolecular Friedel–Crafts alkylation reaction (Scheme 1a) of alcohols [9][10][11], alkenes [12] or acetylenes [13] affords the desired tetrahydrofuro[3,2-c]pyridines. A related method is based on a Au(I)-catalyzed domino sequence dearomatization
  • ][18] was described (Scheme 1c). The most studied variation of this cyclization is based on the generation of an acyliminium cation from the corresponding alcohols [19][20][21][22][23] or alkenes [24][25][26][27][28][29], subsequent attack of furan ring and the formation of annulated tetrahydrofuro[3,2
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Published 30 Jun 2023

The unique reactivity of 5,6-unsubstituted 1,4-dihydropyridine in the Huisgen 1,4-diploar cycloaddition and formal [2 + 2] cycloaddition

  • Xiu-Yu Chen,
  • Hui Zheng,
  • Ying Han,
  • Jing Sun and
  • Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 982–990, doi:10.3762/bjoc.19.73

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  • ; isoquinolino[1,2-f][1,6]naphthyridine; Introduction Among various well-known cycloaddition reactions such as the 1,3-dipolar cycloaddition reaction, Diels–Alder reaction, and the Povarov reaction, the cycloaddition reaction of Huisgen 1,4-dipoles with activated alkenes received increasing attention [1][2][3
  • ][59][60][61][62][63][64], herein, we wish to report the use of 5,6-unsubstituted 1,4-dihydropyridines as electron-deficient alkenes in the Huisgen 1,4-diploar cycloaddition and as electron-rich alkenes in formal [2 + 2] cycloadditions for the efficient synthesis of isoquinolino[1,2-f][1,6
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Published 29 Jun 2023

Synthesis of aliphatic nitriles from cyclobutanone oxime mediated by sulfuryl fluoride (SO2F2)

  • Xian-Lin Chen and
  • Hua-Li Qin

Beilstein J. Org. Chem. 2023, 19, 901–908, doi:10.3762/bjoc.19.68

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  • Xian-Lin Chen Hua-Li Qin School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, 205 Luoshi Road, Wuhan, 430070, PR China 10.3762/bjoc.19.68 Abstract A SO2F2-mediated ring-opening cross-coupling of cyclobutanone oxime derivatives with alkenes was developed for
  • esters and adopted the pre-acylation activation strategies [39][40][41]. Up to now, only one report employed an oxime for the generation of iminyl radicals to obtain the similar products, in which, substrates were limited to the electron-rich alkenes (Scheme 2b) [42]. On the other hand, sulfuryl fluoride
  • possessing representative functional groups was employed subsequently to evaluate the reaction scope and limitations (Scheme 3). Under the optimized conditions, alkenes 2b–e with varying steric effects underwent smooth reaction, yielding the corresponding products 3ab–ae in moderate to good yields (56–68
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Published 22 Jun 2023

First synthesis of acylated nitrocyclopropanes

  • Kento Iwai,
  • Rikiya Kamidate,
  • Khimiya Wada,
  • Haruyasu Asahara and
  • Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2023, 19, 892–900, doi:10.3762/bjoc.19.67

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  • ). These structural features enable the construction of a five-membered ring upon treatment with alkenes [9], diazo compounds (reaction g) [10], and nitriles [11]. Several approaches are available for the synthesis of cyclopropanedicarboxylates 1a, which consist of three steps: 1) conjugate addition, 2
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Published 21 Jun 2023

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

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  • insertion giving intermediate 16’, which upon protonation gives the desired alkylated product 14. Later, in the year 2018, Yao and co-workers [53] developed the first example of a group 4 metal-based catalyst protocol for the C–H alkylation of pyridine 1 with alkenes 18 and 20 as coupling partners. They
  • dialkylpyridines with alkenes. It is to be noted that the ligands’ backbones were found to be crucial for the regioselectivity of the addition to benzylic C(sp3)–H bonds, as N-arylamine-bridged bis(phenolato) Zr complexes provided branched products whereas N-alkylamine-bridged bis(phenolato) Zr complexes provided
  • the aminoalkylated product 27 (Scheme 6b). The selective C–H monoalkylation of pyridines with alkenes is a challenging task. Most ortho-C–H alkylation reactions have been achieved starting from C2-substituted pyridines. There are a few studies reported for the selective C–H monoalkylation of
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Published 12 Jun 2023

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

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  • moderate to good yield (35–82%). 3.5 Ring-closing metathesis Olefin metathesis is a metal-catalysed reaction wherein carbon–carbon double bonds are cleaved and formed through an intermediate cyclometallacarbene 114, thus allowing for transalkylidenation and the formation of mixed alkenes 115 (Scheme 24
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Published 22 May 2023

Photocatalytic sequential C–H functionalization expediting acetoxymalonylation of imidazo heterocycles

  • Deepak Singh,
  • Shyamal Pramanik and
  • Soumitra Maity

Beilstein J. Org. Chem. 2023, 19, 666–673, doi:10.3762/bjoc.19.48

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  • boron complex (B2pin2), and using an expensive metal-based photocatalyst [fac-Ir(ppy)3] under inert atmosphere. We have recently demonstrated that aerial oxygen could be captured by alkyl radicals to install a keto-functionality onto alkenes in an organophotocatalytic way [23]. We aimed to extend this
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Published 12 May 2023

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

  • Péter Kisszékelyi and
  • Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

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  • three-step reaction sequence resulting in trisubstituted nitropyrrolidinones 24 with exceptional enantioselectivity (Scheme 6B). In contrast to conjugate additions to nitroolefins, these activated alkenes can also be utilized in the enolate trapping step. In the last decade, several highly
  • , we have investigated the domino reaction of the formed metal enolates with activated alkenes 91 [59]. Alkenes with two activating groups were needed for efficient enolate-trapping reactions, sulfone or phosphonate activating groups being the most suitable ones (Scheme 23). Harutyunyan and co-workers
  • -alkynylketones 129 in good yields. Conjugate additions with organozirconium reagents The hydrozirconation of alkenes and alkynes generates mild organozirconium compounds that can be used in various transformations. Fletcher and co-workers developed the utilization of organozirconium reagents in Cu-catalyzed
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Published 04 May 2023

C3-Alkylation of furfural derivatives by continuous flow homogeneous catalysis

  • Grédy Kiala Kinkutu,
  • Catherine Louis,
  • Myriam Roy,
  • Juliette Blanchard and
  • Julie Oble

Beilstein J. Org. Chem. 2023, 19, 582–592, doi:10.3762/bjoc.19.43

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  • with good productivity. Alkenes without silicon in the vinyl position seemed much less reactive, such as a vinylacetal, a hindered olefin (3,3-dimethyl-1-butene), or styrene. In these cases, functionalized furfurals were not isolated. In contrast, norbornene, which has a more reactive double bond due
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Published 03 May 2023

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

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  • -pentafluoropropylphosphonate, bearing a trifluoromethyl and a difluoromethyl group is reported for the first time. Its application in CuI-catalyzed cyclopropanation reactions with aromatic and aliphatic terminal alkenes under mild reaction conditions is demonstrated. In total, sixteen new cyclopropanes were synthesized in
  • good to very good yields. Keywords: alkenes; cyclopropanation; diazo compounds; difluoromethylphosphonate; DFT calculations; Introduction Cyclopropanes constitute a fascinating class of organic compounds due to their unique structure and bond properties [1]. However, their synthetic utility is
  • ]. Therefore, as relevant building blocks, tremendous efforts have been made to develop reliable methods for their synthesis. Transition-metal-catalyzed cyclopropanation of alkenes with trifluoromethyldiazoalkanes is a commonly used synthetic strategy for the construction of trifluoromethylcyclopropanes
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Published 25 Apr 2023

Transition-metal-catalyzed domino reactions of strained bicyclic alkenes

  • Austin Pounder,
  • Eric Neufeld,
  • Peter Myler and
  • William Tam

Beilstein J. Org. Chem. 2023, 19, 487–540, doi:10.3762/bjoc.19.38

Graphical Abstract
  • -catalyzed domino reactions of strained bicyclic alkenes, including both homo- and heterobicyclic alkenes. These compounds are important synthons in organic synthesis, providing an important platform for the construction of biologically/medicinally significant compounds which bear multiple stereocenters. The
  • review has been divided according to the metal used in the reaction. An overview of the substrate scope, reaction conditions, and their potential applications in organic synthesis is discussed. A comprehensive outlook on the reactivity paradigms of homo- and heterobicyclic alkenes is discussed and should
  • shed light on future directions for further development in this field. Keywords: bicyclic alkenes; cascade; catalysis; domino; transition-metal-catalyzed; Introduction A well-orchestrated sequence of events – cascade, also known as domino, tandem, and sequential reactions, constitutes a fascinating
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Published 24 Apr 2023

Computational studies of Brønsted acid-catalyzed transannular cycloadditions of cycloalkenone hydrazones

  • Manuel Pedrón,
  • Jana Sendra,
  • Irene Ginés,
  • Tomás Tejero,
  • Jose L. Vicario and
  • Pedro Merino

Beilstein J. Org. Chem. 2023, 19, 477–486, doi:10.3762/bjoc.19.37

Graphical Abstract
  • alkenes under chiral BINOL-derived Brønsted acid catalysis has been studied by Houk and Rueping in 2014 [33]. These authors established the origin of the enantioselectivity and the differences between the catalyzed and uncatalyzed reactions, suggesting that the catalyzed reaction is, actually, a so-called
  • alkene) (Figure 2). Thus, we can consider the reaction of hydrazones with alkenes an inverse-demand cycloaddition with respect to that of azomethine imines (Figure 2). In fact, we monitored the global electron density transfer (GEDT) [34] between the reagents along the reaction coordinate (Figure 3) and
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Published 20 Apr 2023

Group 13 exchange and transborylation in catalysis

  • Dominic R. Willcox and
  • Stephen P. Thomas

Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28

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  • kinetic and computational analyses, the B‒C(sp2)/B‒H transborylation transition state was determined to have a free energy barrier of approximately 20 kcal mol−1 (ΔG‡calc = 19.7 kcal mol−1; ΔG‡exp = 20.3 kcal mol−1) (Scheme 2). The borane-catalysed hydroboration of alkenes has been less explored, with
  • transborylation with HBpin, to give the thioBpin 77 product and regenerate the amine-borane catalyst 73 (Scheme 17). Yamamoto reported the borane-catalysed hydroalumination of alkenes and allenes (Scheme 18) [80][81][82][83] in which the organoaluminium products were reacted in situ with various electrophiles to
  • , including LiAlH4, promoted the decomposition of HBpin to BH3 which can mediate hidden catalysis [56]. Thomas et al. reported the aluminium-catalysed hydroboration of alkenes, using HBpin and LiAlH4 as the catalyst (Scheme 20) [94]. Through single-turnover experiments they suggested a mechanism similar to
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Published 21 Mar 2023

Strategies to access the [5-8] bicyclic core encountered in the sesquiterpene, diterpene and sesterterpene series

  • Cécile Alleman,
  • Charlène Gadais,
  • Laurent Legentil and
  • François-Hugues Porée

Beilstein J. Org. Chem. 2023, 19, 245–281, doi:10.3762/bjoc.19.23

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  • reaction has never been used in the synthesis of natural products before this report, and no β-elimination of the silyloxy group was observed, although this often occurs in such systems [26]. The installation of the two alkenes in 37 required 13 additional steps, and further protecting group manipulations
  • metathesis (EYRCM) reported by Katz in 1985, represents an attractive variant of the classical RCM with the replacement of one of the alkenes by an alkyne function. Thus, EYRCM is atom economic and provides a 1,3 diene, which constitutes an ideal partner for further functionalization, typically a Diels–Alder
  • favoring reactivity with various types of substrates, ranging from halides to carbonyls and alkenes/alkynes. It is comprehensible that this reagent attracted early interest in natural product synthesis and more precisely on medium-sized ring formation. 4.1 SmI2-mediated Barbier-type ring annulation towards
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Published 03 Mar 2023

An accelerated Rauhut–Currier dimerization enabled the synthesis of (±)-incarvilleatone and anticancer studies

  • Tharun K. Kotammagari,
  • Sweta Misra,
  • Sayantan Paul,
  • Sunita Kunte,
  • Rajesh G. Gonnade,
  • Manas K. Santra and
  • Asish K. Bhattacharya

Beilstein J. Org. Chem. 2023, 19, 204–211, doi:10.3762/bjoc.19.19

Graphical Abstract
  • ) dimerization has some limitations, such as its controlling selectivity for intermolecular reactions in differently activated alkenes, and low reactivity. Han and co-workers [6] addressed the latter one by designing a substrate in which nucleophile functionality is also present in the Michael acceptor to
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Published 21 Feb 2023

Germacrene B – a central intermediate in sesquiterpene biosynthesis

  • Houchao Xu and
  • Jeroen S. Dickschat

Beilstein J. Org. Chem. 2023, 19, 186–203, doi:10.3762/bjoc.19.18

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  • catalytic hydrogenation to 27, dehydration to a mixture of alkenes (28) and hydrogenation to selinane (29) it was concluded that 11 was a selinane sesquiterpene alcohol (Scheme 9B) [75]. Four years later, based on NMR data Bhattacharyya and co-workers suggested a cis-ring junction for 11 [76], but a
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Published 20 Feb 2023

Sequential hydrozirconation/Pd-catalyzed cross coupling of acyl chlorides towards conjugated (2E,4E)-dienones

  • Benedikt Kolb,
  • Daniela Silva dos Santos,
  • Sanja Krause,
  • Anna Zens and
  • Sabine Laschat

Beilstein J. Org. Chem. 2023, 19, 176–185, doi:10.3762/bjoc.19.17

Graphical Abstract
  • ethers 12 [19] and metal-catalyzed cross coupling of alkenes 13 and enones 14 [20][21] have been reported. However, these reactions face multiple disadvantages such as limited substrate scope, use of hazardous solvents and harsh reaction conditions such as high temperatures or acidic/basic conditions
  • ]. Since the early work by Wailes, Schwartz and Buchwald on the Schwartz reagent Cp2Zr(H)Cl and its reactivity towards alkynes, alkenes, and C–X double bonds particularly hydrozirconation has gained much attention [25][26][27][28][29][30]. It has been successfully employed in methodology studies [31][32
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Published 17 Feb 2023

1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures

  • Bram Ryckaert,
  • Ellen Demeyere,
  • Frederick Degroote,
  • Hilde Janssens and
  • Johan M. Winne

Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12

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  • dienophiles 7 and 27. 4 Alkylation chemistry of 1,4-dithianes and 1,4-dithiins: stereocontrolled synthesis of Z-alkenes As mentioned in chapter 2 of this review, Palumbo and co-workers found that 5,6-dihydro-1,4-dithiins are relatively resistant to β-elimination in their lithiated form (Scheme 6e), and this
  • should be noted that the three-step strategy (dithiolane protection, oxidative rearrangement, and hydrodesulfurization) can be used to treat carbonyl functional groups as synthetic equivalents of cis-alkenes (Scheme 10c), as is shown by the highly stereoselective conversion of α-phenylacetophenone (60
  • some experimentation, the desired chemoselective transformation can be achieved in almost all cases, including for sensitive substrates such as yohimbine-derived compound 102 [30]. A common problem is the concomitant hydrogenation of alkenes, which can be hard to avoid, as seen in the
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Published 02 Feb 2023

Practical synthesis of isocoumarins via Rh(III)-catalyzed C–H activation/annulation cascade

  • Qian-Ci Gao,
  • Yi-Fei Li,
  • Jun Xuan and
  • Xiao-Qiang Hu

Beilstein J. Org. Chem. 2023, 19, 100–106, doi:10.3762/bjoc.19.10

Graphical Abstract
  • approach towards isocoumarins [17][18]. Pioneering examples relying on the Pd, Ru, and Ir-catalyzed C–H cross coupling of benzoic acids with alkenes and alkynes were realized by the groups of Miura [19], Lee [20], Ackermann [21], Zhang [22], Jiang [23], and Jeganmohan [24] et al. Despite these impressive
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Published 30 Jan 2023

NaI/PPh3-catalyzed visible-light-mediated decarboxylative radical cascade cyclization of N-arylacrylamides for the efficient synthesis of quaternary oxindoles

  • Dan Liu,
  • Yue Zhao and
  • Frederic W. Patureau

Beilstein J. Org. Chem. 2023, 19, 57–65, doi:10.3762/bjoc.19.5

Graphical Abstract
  • future synthetic developments [61][62][63][64][65][66][67]. The NaI/PPh3 system has been further broadly applied to the functionalization of alkenes [68][69][70], as well as to decarboxylative C(sp3)–X bond formation [71], cyclization of 1,7-enynes [72][73] and other reactions [74][75][76][77]. Inspired
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Published 16 Jan 2023

Combining the best of both worlds: radical-based divergent total synthesis

  • Kyriaki Gennaiou,
  • Antonios Kelesidis,
  • Maria Kourgiantaki and
  • Alexandros L. Zografos

Beilstein J. Org. Chem. 2023, 19, 1–26, doi:10.3762/bjoc.19.1

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  • reactions of transition metal hydrides (Fe, Co, Mn, etc) with alkenes (e.g., Mukaiyama hydration) [20]. The last decade saw the development of milder methods for generating carbon-centered radicals as the advancement of their reactivity in cross-coupling reactions, the concept of photoredox catalysis [21
  • ) [30]. HAT reductions of the C9–C11 alkene followed to deliver arisugacin F (35), phenylpyropene C (36), pyripyropene E (38), and phenylpyropene F (41). The steric bulk of the manganese catalyst employed suppressed the undesired reaction with tetrasubstituted alkenes and led to the exclusive reaction
  • -step sequence. The cyclization of the formed radical is 6-exo-trig and leads to the formation of a benzyl radical that is further oxidized to 188. From this common scaffold, the group managed to access several natural products of the class, majorly by utilizing the ability of conjugated alkenes to be
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Published 02 Jan 2023

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

  • Elena R. Lopat’eva,
  • Igor B. Krylov,
  • Dmitry A. Lapshin and
  • Alexander O. Terent’ev

Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179

Graphical Abstract
  • active oxidative agent. Asymmetric quaternary ammonium phase-transfer catalysts proved to be effective in the asymmetric nucleophilic epoxidation of electron-poor alkenes by hydroperoxides [70] and the asymmetric hydroxylation of enolizable carbonyl compounds employing O2 or H2O2 as terminal oxidants [71
  • perform the CH-functionalization of alkanes by electron-deficient alkenes. Photoredox catalysis was employed for the one-electron oxidation of the DABCO-derived organocatalyst to the dication radical. The authors noted that the introduction of a substituent X near the radical center further improves the
  • (for example, amines, alkenes, benzyl ethers) by electron-deficient aryl cyanides under photoredox conditions. An example of such process is presented in Scheme 23 [122]. The key stages of the proposed mechanism include the photoredox-catalyzed generation of a thiyl radical and anion radical from ArCN
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Published 09 Dec 2022

Rhodium-catalyzed intramolecular reductive aldol-type cyclization: Application for the synthesis of a chiral necic acid lactone

  • Motoyuki Isoda,
  • Kazuyuki Sato,
  • Kenta Kameda,
  • Kana Wakabayashi,
  • Ryota Sato,
  • Hideki Minami,
  • Yukiko Karuo,
  • Atsushi Tarui,
  • Kentaro Kawai and
  • Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1642–1648, doi:10.3762/bjoc.18.176

Graphical Abstract
  • formed the corresponding E-silylenolate via 1,4-reduction at 0 °C [46], even if the reaction was performed at −45 °C (Scheme 3). Also in relation to this result, Mikami and his group reported a rhodium-catalyzed carboxylation of alkenes or activated alkenes by using CO2 with Et2Zn, and a similar Rh–H
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Published 02 Dec 2022

Simple synthesis of multi-halogenated alkenes from 2-bromo-2-chloro-1,1,1-trifluoroethane (halothane)

  • Yukiko Karuo,
  • Atsushi Tarui,
  • Kazuyuki Sato,
  • Kentaro Kawai and
  • Masaaki Omote

Beilstein J. Org. Chem. 2022, 18, 1567–1574, doi:10.3762/bjoc.18.167

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Published 21 Nov 2022

A facile approach to spiro[dihydrofuran-2,3'-oxindoles] via formal [4 + 1] annulation reaction of fused 1H-pyrrole-2,3-diones with diazooxindoles

  • Pavel A. Topanov,
  • Anna A. Maslivets,
  • Maksim V. Dmitriev,
  • Irina V. Mashevskaya,
  • Yurii V. Shklyaev and
  • Andrey N. Maslivets

Beilstein J. Org. Chem. 2022, 18, 1532–1538, doi:10.3762/bjoc.18.162

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  • investigated for FPDs: the [4 + 2] cycloaddition with alkenes resulting in pyran-annulated products [27][28][29][30][31][32][33][34] and the [3 + 2] cycloaddition with nitrones resulting in isoxazole-annulated products [35][36][37] (Scheme 2). However, formal [4 + 1] cycloaddition reactions for FPDs remain to
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Published 10 Nov 2022
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