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Search for "Annulation" in Full Text gives 217 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.

Visible-light-mediated copper photocatalysis for organic syntheses

  • Yajing Zhang,
  • Qian Wang,
  • Zongsheng Yan,
  • Donglai Ma and
  • Yuguang Zheng

Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169

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  • . In this work, N,N-dialkylanilines or N-aryltetrahydroisoquinolines 48 reacted with N-substituted maleimide 49 via annulation to provide a range of tetrahydroquinolines or tetrahydroisoquinolines 50, respectively, with good yield. The mechanistic investigation revealed that an α-amino radical
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Published 12 Oct 2021

Copper-catalyzed monoselective C–H amination of ferrocenes with alkylamines

  • Zhen-Sheng Jia,
  • Qiang Yue,
  • Ya Li,
  • Xue-Tao Xu,
  • Kun Zhang and
  • Bing-Feng Shi

Beilstein J. Org. Chem. 2021, 17, 2488–2495, doi:10.3762/bjoc.17.165

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  • in 2020, an enantioselective C–H annulation of ferrocenylformamides with alkynes was achieved by the Ye group enabled by Ni-Al bimetallic catalysis and a chiral secondary phosphine oxide (SPO) ligand [35]. Hou et al. also reported the asymmetric C−H alkenylation of quinoline- and pyridine-substituted
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Published 28 Sep 2021

Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

  • Yi Liu,
  • Puying Luo,
  • Yang Fu,
  • Tianxin Hao,
  • Xuan Liu,
  • Qiuping Ding and
  • Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

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  • , Jiangxi Provincial People’s Hospital Affiliated to Nanchang University, 92 Aiguo Road, Nanchang, Jiangxi, 330006, China 10.3762/bjoc.17.163 Abstract Great progress has been made in the tandem annulation of enynes in the past few years. This review only presents the corresponding reactions of 1,3-enyne
  • introduce the applications of the products and the reaction mechanisms for the synthesis of corresponding N-heterocycles. Keywords: 1,3-enyne; functionalization; pyridine; pyrrole; tandem annulation; Introduction The pyridine moiety is an important class of six-membered N-heterocycles that is widely found
  • pyridine derivatives have been developed through the intramolecular or intermolecular tandem addition annulation/functionalization of alkynes with some N-containing compounds, such as nitriles, oximes, and imines [15][16][17][18][19]. The pyrrole structural motif is also an invaluable five-membered N
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Published 22 Sep 2021

Recent advances in the syntheses of anthracene derivatives

  • Giovanni S. Baviera and
  • Paulo M. Donate

Beilstein J. Org. Chem. 2021, 17, 2028–2050, doi:10.3762/bjoc.17.131

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  • intramolecular cyclization until 2012 [52]. Mohanakrishnan’s group has contributed with numerous methodologies for the synthesis of anthracene derivatives, mainly methodologies involving Lewis acid-mediated intramolecular cyclizations. For example, in 2012 they reported an annulation protocol to synthesize
  • anthracene, tetracene, and naphtho[b]thiophene derivatives via ZnBr2-mediated regioselective annulation of asymmetric 1,2-diarylmethine dipivalates 83a (Scheme 20). On the basis of this methodology, they prepared 37 examples of different types of anthracene derivatives, such as compounds 84a–e, in very good
  • the representative examples 194a–d [81]. In 2017, Mal and Basak applied a [4 + 2] anionic annulation of substituted cyanophthalides 195 with dienoates 196 and obtained 3-allylnaphthoates 197 (Scheme 46) [82]. Then, they converted the naphthoate derivatives 197 to the corresponding alcohols 198 by
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Published 10 Aug 2021

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

  • Renato L. Carvalho,
  • Amanda S. de Miranda,
  • Mateus P. Nunes,
  • Roberto S. Gomes,
  • Guilherme A. M. Jardim and
  • Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

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Published 30 Jul 2021

A recent overview on the synthesis of 1,4,5-trisubstituted 1,2,3-triazoles

  • Pezhman Shiri,
  • Ali Mohammad Amani and
  • Thomas Mayer-Gall

Beilstein J. Org. Chem. 2021, 17, 1600–1628, doi:10.3762/bjoc.17.114

Graphical Abstract
  • takes place to form intermediate 22, which subsequently converts to diazo-functionalized intermediate 23. Finally, the intramolecular annulation of intermediate 23 gives corresponding fully decorated 1,2,3-triazole 19 (Scheme 9) [42]. A domino coupling synthesis of fully decorated 1,2,3-triazole
  • converted to fused sultams (Scheme 30) [56]. Anand et al. reported a Cu-catalyzed one-pot method for the preparation of 1,2,3-triazole-fused tricyclic heterocycles 106 via an intramolecular [3 + 2]-annulation. This strategy includes the 1,6-conjugate addition of Me3SiN3 to o-alkynylated p-quinone methides
  • 105, followed by an intramolecular Click annulation to provide rapid access to a wide range of desired 1,2,3-triazole-fused isoindolines 108 with a reasonable yield. The reaction was carried out well by using o-alkynylated p-quinone methides 105 and TMSN3 in the presence of a catalytic amount of CuOTf
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Published 13 Jul 2021

Copper-mediated oxidative C−H/N−H activations with alkynes by removable hydrazides

  • Feng Xiong,
  • Bo Li,
  • Chenrui Yang,
  • Liang Zou,
  • Wenbo Ma,
  • Linghui Gu,
  • Ruhuai Mei and
  • Lutz Ackermann

Beilstein J. Org. Chem. 2021, 17, 1591–1599, doi:10.3762/bjoc.17.113

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  • context, You [25], Huang [26], Liu [27], Li [28], and co-workers elegantly disclosed copper-mediated/catalyzed cascade C−H alkynylation and annulation with terminal alkynes to afford 3-methyleneisoindolinone derivatives, through the assistance of 8-aminoquinoline [29] or 2-aminophenyl-1H-pyrazole [30
  • ] auxiliaries (Figure 1a). Besides, the cobalt(II)- [31] or nickel(II)-catalyzed [32][33], pyridine oxide (PyO)-directed tandem alkynylation/annulation was realized by Niu and Song et al., which also provided the 3-methyleneisoindolin-1-one scaffolds (Figure 1b). Notably, a sustainable cupraelectro-catalyzed
  • alkyne annulation was very recently achieved by Ackermann et al., which gave rapid access to synthetically meaningful isoindolones (Figure 1c) [34]. In spite of these indisputable advances, the successful removal of the directing groups to deliver the free-NH 3-methyleneisoindolin-1-one has thus far
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Published 08 Jul 2021

Synthesis of 1-indolyl-3,5,8-substituted γ-carbolines: one-pot solvent-free protocol and biological evaluation

  • Premansh Dudhe,
  • Mena Asha Krishnan,
  • Kratika Yadav,
  • Diptendu Roy,
  • Krishnan Venkatasubbaiah,
  • Biswarup Pathak and
  • Venkatesh Chelvam

Beilstein J. Org. Chem. 2021, 17, 1453–1463, doi:10.3762/bjoc.17.101

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  • extreme thermal conditions with the use of corrosive reagents. Much later, Larock and co-workers developed a Pd/Cu-catalyzed imino-annulation of internal alkynes [15], which paved the way for transition-metal-catalyzed cyclizations as easy access to these scaffolds. Notably, the gold-catalyzed tandem
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Published 17 Jun 2021

N-tert-Butanesulfinyl imines in the asymmetric synthesis of nitrogen-containing heterocycles

  • Joseane A. Mendes,
  • Paulo R. R. Costa,
  • Miguel Yus,
  • Francisco Foubelo and
  • Camilla D. Buarque

Beilstein J. Org. Chem. 2021, 17, 1096–1140, doi:10.3762/bjoc.17.86

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  • -pyrrolines 82 were formed as single diastereomers [101]. The whole process could be considered a [3 + 2] annulation, and aziridines were not observed as competing reaction products (see above Scheme 11). In addition, hindered imines, ethers, sulfonates, heteroaryl substituents, and conjugated imines were all
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Published 12 May 2021

Prins cyclization-mediated stereoselective synthesis of tetrahydropyrans and dihydropyrans: an inspection of twenty years

  • Asha Budakoti,
  • Pradip Kumar Mondal,
  • Prachi Verma and
  • Jagadish Khamrai

Beilstein J. Org. Chem. 2021, 17, 932–963, doi:10.3762/bjoc.17.77

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  • and trans-2,6-DHP, respectively, was reported by a [4 + 2]-annulation strategy. The authors utilized crotylsilanes syn-170 and anti-170, respectively, with an aldehyde 171 in the presence of TMSOTf to deliver different DHPs 172 (Scheme 41) [76]. For syn-170, the reaction went via the favored boat-like
  • synthesized utilizing this [4 + 2]-annulation strategy. Following the above annulation route, later, Roush's group Introduced β-hydroxyallylsilanes for the synthesis of 2,6-disubstituted DHP (Scheme 44) [82]. This strategy was further utilized for the synthesis of the C29−C45 bispyran subunit (E−F) of
  • -crotylsilanes. Roush and co-workers’ [4 + 2]-annulation strategy for DHP synthesis [82]. TMSOTf-promoted annulation reaction. Dobb and co-workers’ synthesis of DHP. BiBr3-promoted tandem silyl-Prins reaction by Hinkle et al. Substrate scope of Hinkle and co-workers’ strategy. Cho and co-workers’ strategy for
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Published 29 Apr 2021

Annulation of a 1,3-dithiole ring to a sterically hindered o-quinone core. Novel ditopic redox-active ligands

  • Sergey V. Norkov,
  • Anton V. Cherkasov,
  • Andrey S. Shavyrin,
  • Maxim V. Arsenyev,
  • Viacheslav A. Kuropatov and
  • Vladimir K. Cherkasov

Beilstein J. Org. Chem. 2021, 17, 273–282, doi:10.3762/bjoc.17.26

Graphical Abstract
  • annulation of sterically hindered o-quinones with a 2-substituted 1,3-dithiole cycle seems to be a promising tool for the preparation of redox-active dioxolene species bearing additional functionalities. The previously described o-quinones with an annulated 1,3-dithiole fragment display a remarkable
  • coordination ability towards metal ions. The versatile chemistry of precursors used for annulation of the 1,3-dithiole moiety to an o-quinone ring allows a wide variety of substituents at the 2-position of the 1,3-dithiole cycle, including additional redox-active, coordination-capable or free-radical functions
  • ][10][11][12][13], whereas methods resulting in the synthesis of o-quinone analogs are scarce. Results and Discussion Previously we reported an efficient synthesis pathway for the annulation of the 1,3-dithiole cycle to the 4,5-positions of an o-quinone ring using the reaction of 3,6-di-tert-butyl-4
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Published 27 Jan 2021

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

Graphical Abstract
  • , carbanion, and radical chemistry. Furthermore, gem-difluorocyclopropanes readily go through carbonylation, dehalogenation, and annulation, resulting in various useful materials. 2.1 Thermal rearrangements The substitution of hydrogen with fluorine in cyclopropane leads to a significant weakening of the C–C
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Published 26 Jan 2021

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

Graphical Abstract
  • natural product syntheses featuring all-carbon [3 + 2] annulation are elaborated. Lastly, we discuss future directions and opportunities for the all-carbon [3 + 2] cycloaddition. Review In 1981, Little and co-workers utilized a trimethylenemethane (TMM) cycloaddition as the key reaction to synthesize the
  • rearrangement product 99 in 85% yield. The synthesis of daphenylline (11) was completed by a seven-step synthesis from benzofuran 99. Phosphine-catalyzed enantioselective [3 + 2] annulation In 2019, Lu and co-workers disclosed a novel chiral-phosphine-catalyzed enantioselective [3 + 2] annulation of allenes and
  • isoindigos to give an enantioenriched annulation adduct bearing vicinal quaternary stereocenters [46] (Scheme 7A). Both symmetric and unsymmetric isoindigos can undergo enantioselective [3 + 2] annulation with an allene and produced a chiral adduct with high yield and high ee value. When unsymmetric
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Published 09 Dec 2020

Three-component reactions of aromatic amines, 1,3-dicarbonyl compounds, and α-bromoacetaldehyde acetal to access N-(hetero)aryl-4,5-unsubstituted pyrroles

  • Wenbo Huang,
  • Kaimei Wang,
  • Ping Liu,
  • Minghao Li,
  • Shaoyong Ke and
  • Yanlong Gu

Beilstein J. Org. Chem. 2020, 16, 2920–2928, doi:10.3762/bjoc.16.241

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  • -bromoacetaldehyde acetal by using aluminum(III) chloride as a Lewis acid catalyst through [1 + 2 + 2] annulation. This new versatile methodology provides a wide scope for the synthesis of different functional N-(hetero)aryl-4,5-unsubstituted pyrrole scaffolds, which can be further derived to access multisubstituted
  • pyrrole-3-carboxamides. In the presence of 1.2 equiv of KI, a polysubstituted pyrazolo[3,4-b]pyridine derivative was also successfully synthesized. Keywords: acid catalyst; [1 + 2 + 2] annulation; KI; pyrazolo[3,4-b]pyridine; pyrroles; Introduction Among nitrogen-containing heterocycles, pyrroles have
  • , the transformations can generally be realized through the following three approaches (Scheme 1): (i) [1 + 1 + 3] annulation, in which (hetero)arylamines are reacted with a C3 donor and a C1 donor to construct pyrrole scaffolds. Kumar et al. [26] developed a proline-catalyzed Mannich reaction
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Published 30 Nov 2020

Synthesis and characterization of S,N-heterotetracenes

  • Astrid Vogt,
  • Florian Henne,
  • Christoph Wetzel,
  • Elena Mena-Osteritz and
  • Peter Bäuerle

Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214

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  • -dibromothiophene 6 and Pd(dppf)Cl2 as catalyst to give the corresponding dibromide 7 in a yield of 70%. Organozinc species 6 was obtained from 2,3-dibromothiophene by lithiation with n-BuLi and reaction with zink dichloride. Annulation to TIPS-protected SN4-Hex 8 was achieved in 87% yield by a tandem Buchwald
  • provide carbazoles covering a wide substrate and functional group spectrum [41]. Moreover, penta- and heptafused heteroacenes were prepared by the Cadogan reaction by annulation of nitrophenyl or nitrobenzothienyl precursors [42][43][44][45]. In this respect, we recently reported a Cadogan cyclization of
  • -heterotetracene system SN4'' comprising the heteroatom sequence ‘SNNS’ is built-up by annulation of two ‘outer’ thiophene and two ‘inner’ pyrrole rings resulting in the symmetric sequence of heteroatoms in the tetracyclic conjugated π-system. The multistep synthesis of Pr-SN4'' 33 started from 2
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Published 26 Oct 2020

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

  • Shakeel Alvi and
  • Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

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Published 09 Sep 2020

Synthesis of 6,13-difluoropentacene

  • Matthias W. Tripp and
  • Ulrich Koert

Beilstein J. Org. Chem. 2020, 16, 2136–2140, doi:10.3762/bjoc.16.181

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  • Matthias W. Tripp Ulrich Koert Department of Chemistry, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35034 Marburg, Germany 10.3762/bjoc.16.181 Abstract 6,13-Difluoropentacene was synthesized from 1,4-difluorobenzene. Friedel–Crafts annulation of the latter with phthalic anhydride and
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Published 02 Sep 2020

Synthesis and highly efficient light-induced rearrangements of diphenylmethylene(2-benzo[b]thienyl)fulgides and fulgimides

  • Vladimir P. Rybalkin,
  • Sofiya Yu. Zmeeva,
  • Lidiya L. Popova,
  • Valerii V. Tkachev,
  • Andrey N. Utenyshev,
  • Olga Yu. Karlutova,
  • Alexander D. Dubonosov,
  • Vladimir A. Bren,
  • Sergey M. Aldoshin and
  • Vladimir I. Minkin

Beilstein J. Org. Chem. 2020, 16, 1820–1829, doi:10.3762/bjoc.16.149

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  • persistance to photodegradation. It has been shown that annulation of benzene rings to the five-membered rings of pyrryl, thienyl and furanyl fulgides can promote the additional improvement of these properties [10][18][19][20][21]. In accordance with these data, we have previously synthesized and studied the
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Published 22 Jul 2020

When metal-catalyzed C–H functionalization meets visible-light photocatalysis

  • Lucas Guillemard and
  • Joanna Wencel-Delord

Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147

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  • photocatalyst. The strategy was utilized for the C–H bond annulation of benzamides with alkynes, furnishing isoquinolones, an important moiety in various natural products (Figure 15) [78]. The C–H activation step was assisted by an 8-quinolyl DG and occurred under an oxygen atmosphere at room temperature. A
  • an aromatic unit in α-position to the nitrogen atom. Sensitive functional groups such as hydroxy, silyl, and ethynyl were tolerated by this protocol. Furthermore, this methodology was also extended towards the C–H annulation with dienes. The proposed mechanism of this reaction requiring only oxygen
  • elimination, producing a Co(I) species. Finally, the photoexcited eosin Y reoxidizes Co(I) to Co(II), while the photosensitizer is reoxidized by molecular oxygen, thus completing the overall catalytic process. In addition, a complementary strategy towards photocatalytic C–H annulation was disclosed by Rueping
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Published 21 Jul 2020

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

  • Alessandra Del Tito,
  • Havall Othman Abdulla,
  • Davide Ravelli,
  • Stefano Protti and
  • Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123

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  • sulfonyl radical, prone to start a tandem sulfonylation/annulation of vinyl azides [84]. Recently, the phenanthridine core was assembled through a radical cascade triggered by the trifluoromethylthiolation of N-(o-cyanobiaryl)acrylamides. The process occurred under visible-light irradiation (6 W blue LED
  • Pd(OAc)2 (5 mol %), was involved in the design of an efficient annulation between benzamides and in situ-generated arynes. The process occurred under oxygen saturated atmosphere at room temperature, likewise offering a straightforward access to the phenanthridone backbone [93]. Conclusion
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Published 25 Jun 2020

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

  • Yeersen Patehebieke

Beilstein J. Org. Chem. 2020, 16, 1418–1435, doi:10.3762/bjoc.16.118

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  • [3 + 2] methylenecyclopentane annulations of olefins with methylenecyclopropanes. This regioselective, mild, and protecting group-free annulation requires only an equimolar amount of the reacting alkene and does not require an excess of the reacting alkene, unlike other methods [9]. Furthermore, the
  • olefins, this method could not give satisfactory results. In order to overcome this weakness, the authors also developed disulfide-catalyzed [3 + 2] methylenecyclopentane annulations of unactivated alkenes with methylenecyclopropanecarboxylates and -dicarboxylates 11 (Scheme 4b) [11]. This annulation
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Published 23 Jun 2020

Recent synthesis of thietanes

  • Jiaxi Xu

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

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  • from that of enones. The latter underwent the [2 + 2] annulation with olefins at their olefinic center to yield cyclobutane derivatives, and rarely undergo oxetane formation completely. The reaction parameters such as solvent affected the balance between the cyclobutane and oxetane formation. Whereas
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Published 22 Jun 2020

Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole

  • Carlos H. Escalante,
  • Eder I. Martínez-Mora,
  • Carlos Espinoza-Hicks,
  • Alejandro A. Camacho-Dávila,
  • Fernando R. Ramos-Morales,
  • Francisco Delgado and
  • Joaquín Tamariz

Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113

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  • activity [15][16] and great diversity as building block [17][18]. Among the tetracyclic scaffolds, isoindolo[2,1-a]indoles have attracted a particular interest from the synthetic point of view, either as the target or the motif for designing novel annulation methodologies [19][20][21]. Indeed, isoindole
  • annulation process through a Pd- or Ni-catalyzed coupling starting from the N-functionalized indoles 5 [11][19][21][28][29][30]. On the other hand, the formation of pyrrolo[3,4-e]indoles 9/10 can be achieved via a Diels–Alder cyloaddition of 2-vinylpyrroles 8 with maleimides 7 [31][32][33][34][35]. This is a
  • representative example of the less common approach for the construction of the indole skeleton on substituted pyrroles by generating the benzene ring via an annulation process [36][37][38][39]. Due to our interest in transforming simple five-membered heterocycles into natural products [40][41] and complex aza
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Published 17 Jun 2020

Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

  • Stephanie G. E. Amos,
  • Marion Garreau,
  • Luca Buzzetti and
  • Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

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  • opening of nitrogen-containing small rings was also exploited by our group in 2019 (Scheme 36) [154]. Starting from the aminocyclopropanes 36.1 and the cyclopropenes 36.2, a [3 + 2] annulation led to the bicyclo[3.1.0]hexanes 36.3. Under visible-light irradiation, the excited-state photocatalyst OD7
  • performs an SET oxidation of an cyclopropylaniline 36.1, leading to an N-centred radical cation after ring opening. The latter undergoes a [3 + 2] annulation with cyclopropenes 36.2, affording a bicyclic product 36.3. The key to the broad substrate tolerance relied on using 4DPAIPN (OD7), which is a mild
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Published 29 May 2020

A simple and easy to perform synthetic route to functionalized thienyl bicyclo[3.2.1]octadienes

  • Dragana Vuk,
  • Irena Škorić,
  • Valentina Milašinović,
  • Krešimir Molčanov and
  • Željko Marinić

Beilstein J. Org. Chem. 2020, 16, 1092–1099, doi:10.3762/bjoc.16.96

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  • , which could be accompanied by a photochemical annulation. The photolysis spectra of compound's 3 isomers are shown in Figure 5, as representative examples. Figure 6 presents the UV spectra of products' 3–7 trans-isomers. All the isomers showed an absorption maxima between 300–400 nm. It can be noticed
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Published 22 May 2020
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