Computation-guided scaffold exploration of 2E,6E-1,10-trans/cis-eunicellanes

• Zining Li,
• Sana Jindani,
• Volga Kojasoy,
• Teresa Ortega,
• Erin M. Marshall,
• Khalil A. Abboud,
• Sandra Loesgen,
• Dean J. Tantillo and
• Jeffrey D. Rudolf

Beilstein J. Org. Chem. 2024, 20, 1320–1326, doi:10.3762/bjoc.20.115

• intrinsic properties, which result in protonation-initiated cyclization, Cope rearrangement, and atropisomerism. Finally, we exploited the reactivity of the trans-eunicellane skeleton to generate a series of 6/6/6 gersemiane-type diterpenes via electrophilic cyclization. Keywords: atropisomer; Cope

• rearrangement; DFT calculations; diterpene; electrophilic cyclization; eunicellane; Introduction The eunicellane diterpenoids are a family of nearly 400 natural products that present a conserved 6/10-bicyclic hydrocarbon framework [1][2][3]. Mostly known from soft corals [2], but with a growing number of

N-Sulfenylsuccinimide/phthalimide: an alternative sulfenylating reagent in organic transformations

• Fatemeh Doraghi,
• Seyedeh Pegah Aledavoud,
• Mehdi Ghanbarlou,
• Bagher Larijani and
• Mohammad Mahdavi

Beilstein J. Org. Chem. 2023, 19, 1471–1502, doi:10.3762/bjoc.19.106

• intermediate led to intramolecular cyclization. In 2020, electrophilic cyclization of allylic amides 134 using N-(phenylthio)succinimide 1 in the presence of camphorsulfonic acid (CSA) as a Brønsted acid and tetrabutylammonium chloride (TBAC) led to 5-[(phenylthio)methyl]oxazoline scaffolds 135 (Scheme 57) [89

• of unactivated arenes. Iron- or boron-catalyzed C–H arylthiation of substituted phenols. Iron-catalyzed azidoalkylthiation of alkenes. Plausible mechanism for iron-catalyzed azidoalkylthiation of alkenes. BF3·Et2O‑mediated electrophilic cyclization of aryl alkynoates. Tentative mechanism for BF3·Et2O

• ‑mediated electrophilic cyclization of aryl alkynoates. Construction of 6-substituted benzo[b]thiophenes. Plausible mechanism for construction of 6-substituted benzo[b]thiophenes. AlCl3‑catalyzed cyclization of N‑arylpropynamides with N‑sulfanylsuccinimides. Synthetic utility of AlCl3‑catalyzed cyclization

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

Me₃Al-mediated domino nucleophilic addition/intramolecular cyclisation of 2-(2-oxo-2-phenylethyl)benzonitriles with amines; a convenient approach for the synthesis of substituted 1-aminoisoquinolines

• Krishna M. S. Adusumalli,
• Lakshmi N. S. Konidena,
• Hima B. Gandham,
• Krishnaiah Kumari,
• Krishna R. Valluru,
• Satya K. R. Nidasanametla,
• Venkateswara R. Battula and
• Hari K. Namballa

Beilstein J. Org. Chem. 2021, 17, 2765–2772, doi:10.3762/bjoc.17.186

• of isoquinoline N-oxides [41][42], condensation of lithiated o‐tolualdehyde tert‐butylimines with nitriles [43], electrophilic cyclization of 2-alkynylbenzamides [44][45] or 2-alkynylbenzaldoximes [46][47][48][49][50][51][52][53][54], oxidative C–H functionalizations (coupling) on aryl and heteroaryl

Advances in mercury(II)-salt-mediated cyclization reactions of unsaturated bonds

• Sumana Mandal,
• Raju D. Chaudhari and
• Goutam Biswas

Beilstein J. Org. Chem. 2021, 17, 2348–2376, doi:10.3762/bjoc.17.153

• ]. Devan et al. had developed similar types of Hg(TFA)2-mediated cyclizations of allene 116 at low temperature followed by reduction with alkaline NaBH4 to form cyclized product 117 in moderate yield [88]. The reaction was believed to proceed through Hg(II) ion-promoted electrophilic cyclization (Scheme 35

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

• 129b via double iodonium-induced electrophilic cyclization. The terphenyl 130 was converted to the diiododibenzo[a,j]anthracene derivative 132 in two steps comprising cyclization and further treatment of intermediate 131 with sulfuric acid [64]. Watanabe and co-workers investigated the oxidative

• . AuCl-catalyzed double cyclization of diiodoethynylterphenyl compounds. Iodonium-induced electrophilic cyclization of terphenyl derivatives. Oxidative photocyclization of 1,3-distyrylbenzene derivatives. Oxidative cyclization of 2,3-diphenylnaphthalenes. Suzuki-Miyaura/isomerization/ring closing

Reactions of 3-aryl-1-(trifluoromethyl)prop-2-yn-1-iminium salts with 1,3-dienes and styrenes

• Thomas Schneider,
• Michael Keim,
• Bianca Seitz and
• Gerhard Maas

Beilstein J. Org. Chem. 2020, 16, 2064–2072, doi:10.3762/bjoc.16.173

• -substituted propyn-1-iminium salts is also exemplified by the Diels–Alder reaction of 1a with anthracene (Scheme 3). After 12 h at room temperature, a 91% conversion was observed, and subsequent moderate heating gave the cycloaddition product 10 in 95% yield. The subsequent iminium-induced electrophilic

• cyclization required extended heating in refluxing toluene and finally furnished the neutral polycycle 11 in good yield. The paddlewheel-shaped structure of 11 was established by an XRD structure determination and is shown in Figure 1. The reactivity of 1a in the Diels–Alder reaction with anthracene may be

Generation of 1,2-oxathiolium ions from (arysulfonyl)- and (arylsulfinyl)allenes in Brønsted acids. NMR and DFT study of these cations and their reactions

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov,
• Olesya V. Khoroshilova and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2018, 14, 2897–2906, doi:10.3762/bjoc.14.268

• high positive charge on it. Another pathway may be an electrophilic cyclization at the ortho-carbon in the S-phenyl ring. Then, the preparative reactions of allene 2a under the action of different electrophilic reagents were conducted. Transformations of 2a using an excess of various Brønsted acids

One-pot preparation of 4-aryl-3-bromocoumarins from 4-aryl-2-propynoic acids with diaryliodonium salts, TBAB, and Na₂S₂O₈

• Teppei Sasaki,
• Katsuhiko Moriyama and
• Hideo Togo

Beilstein J. Org. Chem. 2018, 14, 345–353, doi:10.3762/bjoc.14.22

• ). Thus, the iodonium-based or bromonium-based electrophilic cyclization of phenyl 3-phenyl-2-propynoate (2Aa) does not proceed efficiently. Then, the bromo-radical-based cyclization of phenyl 3-phenyl-2-propynoate (2Aa) with tetrabutylammonium bromide (TBAB, 2.0 equiv)/Na2S2O8 (1.5 equiv) [31] in a

Synthesis and photophysical properties of novel benzophospholo[3,2-b]indole derivatives

• Mio Matsumura,
• Mizuki Yamada,
• Atsuya Muranaka,
• Misae Kanai,
• Naoki Kakusawa,
• Daisuke Hashizume,
• Masanobu Uchiyama and
• Shuji Yasuike

Beilstein J. Org. Chem. 2017, 13, 2304–2309, doi:10.3762/bjoc.13.226

• Scheme 1. The key precursor 2 was synthesized by I2-mediated electrophilic cyclization of 2-ethynyl-N,N-dimethylaniline 1 [36][37]. Treatment of compound 2 with n-butyllithium in anhydrous THF at −78 °C and subsequently with PhPCl2 resulted in ring closure, affording the desired benzophospholo[3,2-b

Transition-metal-free one-pot synthesis of alkynyl selenides from terminal alkynes under aerobic and sustainable conditions

• Adrián A. Heredia and
• Alicia B. Peñéñory

Beilstein J. Org. Chem. 2017, 13, 910–918, doi:10.3762/bjoc.13.92

• acetylenes. Keywords: alkynyl selenide; electrophilic cyclization; nucleophilic substitution; potassium selenocyanate; terminal alkynes; Introduction Alkynyl selenides, as many other selenium compounds, have potential anti-oxidant activities, and may play a role in certain diseases such as cancer, heart

Nucleophilic and electrophilic cyclization of N-alkyne-substituted pyrrole derivatives: Synthesis of pyrrolopyrazinone, pyrrolotriazinone, and pyrrolooxazinone moieties

• Işıl Yenice,
• Sinan Basceken and
• Metin Balci

Beilstein J. Org. Chem. 2017, 13, 825–834, doi:10.3762/bjoc.13.83

• Isil Yenice Sinan Basceken Metin Balci Department of Chemistry, Middle East Technical University, 06800 Ankara, Turkey Department of Chemistry, Hitit University, 19030 Corum, Turkey 10.3762/bjoc.13.83 Abstract Intramolecular nucleophilic and electrophilic cyclization of N-alkyne-substituted

• ; HRMS: [M + H]+ calcd for C11H15N3O, 206.12879; found, 206.13010. General procedure for electrophilic cyclization reactions of 7 with iodine. To a solution of N-alkyne-substituted methyl 1H-pyrrole-2-carboxylate derivatives 7 in dichloromethane (10 mL), I2 (1.0 equiv) was added. The reaction mixture was

• cyclization reactions of 19a–c with iodine. Proposed reaction mechanism of electrophilic cyclization reaction of 7c. Supporting Information Supporting Information File 146: NMR spectra, X-ray crystallographic data, and Cartesian Coordinates for the optimized structures. Acknowledgments Financial support

Symmetry-based approach to oligostilbenoids: Rapid entry to viniferifuran, shoreaphenol, malibatol A, and diptoindonesin G

• Youngeun Jung,
• Dileep Kumar Singh and
• Ikyon Kim

Beilstein J. Org. Chem. 2016, 12, 2689–2693, doi:10.3762/bjoc.12.266

• groups have been used as nucleophiles of iodocyclization for the syntheses of a number of heterocycles, respectively [27][28][29][30]. Although Larock’s work on relative reactivity of these functional groups toward alkyne during electrophilic cyclization has been reported [31], the study with the

• competitively involved in the iodine-mediated electrophilic cyclization. Only a trace amount of 10 was isolated upon subjection of 5 to the same reaction conditions. We suspected that the aldehyde in 5 also acted as a nucleophile to furnish unstable oxocarbenium species (inset box of Scheme 3) as a major

Come-back of phenanthridine and phenanthridinium derivatives in the 21st century

• Lidija-Marija Tumir,
• Marijana Radić Stojković and
• Ivo Piantanida

Beilstein J. Org. Chem. 2014, 10, 2930–2954, doi:10.3762/bjoc.10.312

• intramolecular hydroarylation or via iodo-catalysed regioselective 6-endo-dig electrophilic cyclization. Kitson et al. synthesized a class of 2,3-dihydro-12H-pyrrolo[1,2-f]phenanthridine (DPP) derivatives starting from malononitrile and 1,3-indandione as the initial nucleophiles, which reacted with N

Synthesis of 2-trifluoromethylpyrazolo[5,1-a]isoquinolines via silver triflate-catalyzed or electrophile-mediated one-pot tandem reaction

• Xiaoli Zhou,
• Meiling Liu,
• Puying Luo,
• Yingjun Lai,
• Tangtao Yang and
• Qiuping Ding

Beilstein J. Org. Chem. 2014, 10, 2286–2292, doi:10.3762/bjoc.10.238

• 1i reacted with 2, leading to the desired pyrazolo[5,1-a]isoquinoline 3i in 90% yield (Table 2, entry 9). Subsequently, based on our previous reports on electrophile-mediated electrophilic cyclization reaction [28][29], one-pot tandem electrophilic cyclization/[3 + 2] cycloaddition of N’-(2

• 13C NMR, HRMS, as well as X-ray diffraction analysis (Figure 1, for details, see Supporting Information File 1). Based on this one-pot tandem electrophilic cyclization/[3 + 2] cycloaddition reactions, highly functionalized pyrazolo[5,1-a]isoquinolines can be obtained via palladium-catalyzed cross

Tandem aldehyde–alkyne–amine coupling/cycloisomerization: A new synthesis of coumarins

• Maddi Sridhar Reddy,
• Nuligonda Thirupathi and
• Madala Haribabu

Beilstein J. Org. Chem. 2013, 9, 180–184, doi:10.3762/bjoc.9.21

• transition-metal catalysts (based on gold, mercury, platinum, silver, etc.), Brønsted acids and electrophilic iodine sources (I2, ICl, NIS) have been used for the transformation. If one of the partners in A3 coupling has any nucleophile for concomitant electrophilic cyclization on the alkyne group in the A3

• electrophilic cyclization of the intermediate hydroxyphenylpropargylamine as shown in Scheme 1 (d). We initially investigated the reaction with various Cu-, Au- and Pd-based catalysts in the presence of pyrrolidine in MeCN at room temperature (Table 1). The required product was obtained but in very low yield

When gold can do what iodine cannot do: A critical comparison

• Sara Hummel and
• Stefan F. Kirsch

Beilstein J. Org. Chem. 2011, 7, 847–859, doi:10.3762/bjoc.7.97

• cyclization process and eliminated competing reaction pathways. It was found that even haloalkynes could be employed in this type of cyclization to give doubly halogenated alkenes. The closely related synthesis of 3-iodo-1H-indenes such as 47 via electrophilic cyclization was examined by Wirth and co-workers

• numerous domino processes can be carried out with either gold catalysts or iodine electrophiles to access the same core unit in an analogous manner. While electrophilic cyclization can incorporate iodine into the final product, gold catalysis typically results in hydrogen at the same position due to the

• protodeauration step required for catalyst regeneration. It is certain that many more reactions that have been described as gold-catalyzed will also be described as iodine mediated in the near future. Apparent in this small survey is also the fact that the electrophilic cyclization mode always proceeds through

Total synthesis of (±)-coerulescine and (±)-horsfiline

• Mukund G. Kulkarni,
• Attrimuni P. Dhondge,
• Sanjay W. Chavhan,
• Ajit S. Borhade,
• Yunnus B. Shaikh,
• Deekshaputra R. Birhade,
• Mayur P. Desai and
• Nagorao R. Dhatrak

Beilstein J. Org. Chem. 2010, 6, 876–879, doi:10.3762/bjoc.6.103

• radical cyclizations [20][21][22][23][24], electrophilic cyclization [25], asymmetric nitroolefination reaction [26], palladium asymmetric allylic alkylation [27], palladium-catalyzed domino Heck–cyanation [28], Pd-catalyzed intramolecular cyanoamidation [29][30], NHC-mediated O- to C-carboxyl transfer

Synthesis of crispine A analogues via an intramolecular Schmidt reaction

• Ajoy Kapat,
• Ponminor Senthil Kumar and
• Sundarababu Baskaran

Beilstein J. Org. Chem. 2007, 3, No. 49, doi:10.1186/1860-5397-3-49

• indolizidine skeleton using an epoxide initiated electrophilic cyclization of azide as a key step. This novel methodology has been efficiently applied in the stereo- and enantioselective synthesis of indolizidine 167B and 209D (Scheme 1). [16][17][18] Results and discussion In 2002, a new indolizidine alkaloid

• the synthesis of a library of anti-cancer analogues. The structure activity relationships (SAR) and anti-cancer activities of our synthetic derivatives will be reported in due course of time. ORTEP diagram of the acid derivative 4. Epoxide initiated electrophilic cyclization of azide. Crispine A and