Preparation of β-cyclodextrin-based dimers with selectively methylated rims and their use for solubilization of tetracene

• Konstantin Lebedinskiy,
• Volodymyr Lobaz and
• Jindřich Jindřich

Beilstein J. Org. Chem. 2022, 18, 1596–1606, doi:10.3762/bjoc.18.170

• could be expected that the extension of the hydrophobic cavity by the combined methylation and “dimerization” may improve the binding potential towards such substrates even more. Linear polycyclic aromatic hydrocarbons (acenes) and their derivatives are good organic semiconductors and show interesting

Dissecting Mechanochemistry III

• Lars Borchardt and
• José G. Hernández

Beilstein J. Org. Chem. 2022, 18, 1454–1456, doi:10.3762/bjoc.18.150

• Margetić used dibrominated polycyclic imides as substrates to generate reactive alkenes, which could be trapped in situ by several dienes through Diels−Alder cycloadditions by ball milling (Scheme 3) [7]. Further, Moores and co-workers synthesized phosphorus-bridged heptazine-based carbon nitrides (g-h-PCN

• . Mechanochemical palladium-catalyzed borylation protocol of aryl halides. 1,2-Debromination of polycyclic imides, followed by in situ trapping of the dienophile by several dienes. Synthesis of g-h-PCN from sodium phosphide and trichloroheptazine mediated by mechanochemistry. Mechanochemical intra- and

1,4,6,10-Tetraazaadamantanes (TAADs) with N-amino groups: synthesis and formation of boron chelates and host–guest complexes

• Artem N. Semakin,
• Ivan S. Golovanov,
• Yulia V. Nelyubina and
• Alexey Yu. Sukhorukov

Beilstein J. Org. Chem. 2022, 18, 1424–1434, doi:10.3762/bjoc.18.148

• Tripodal molecules are widely used as chelating ligands for transition metal catalysis [1][2][3], sensors for ions and small molecules [4][5], reagents for surface grafting [6], building blocks for the construction of supramolecular structures [7], polycyclic cage molecules [8], and porous materials [9

Cytochrome P450 monooxygenase-mediated tailoring of triterpenoids and steroids in plants

• Karan Malhotra and
• Jakob Franke

Beilstein J. Org. Chem. 2022, 18, 1289–1310, doi:10.3762/bjoc.18.135

• polycyclic skeletons of triterpenoids and steroids are created by oxidosqualene cyclases (OSCs) from the universal substrate 2,3-oxidosqualene [5]. As different folding modes (chair–boat–chair vs chair–chair–chair) and different ring sizes can occur during this cyclisation cascade, resulting triterpene and

Enzymes in biosynthesis

• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2022, 18, 1131–1132, doi:10.3762/bjoc.18.116

• proceed through multistep cationic cascade reactions and usually produce a polycyclic terpene hydrocarbon or alcohol with multiple stereogenic centers. While these transformations require only a single enzyme, polyketide and nonribosomal peptide biosyntheses are catalyzed by megasynthases that follow an

Isolation and biosynthesis of daturamycins from Streptomyces sp. KIB-H1544

• Yin Chen,
• Jinqiu Ren,
• Ruimin Yang,
• Jie Li,
• Sheng-Xiong Huang and
• Yijun Yan

Beilstein J. Org. Chem. 2022, 18, 1009–1016, doi:10.3762/bjoc.18.101

• skeleton exhibit a large number of structural diversity due to the differences of the center ring and the connection among rings. Structurally, most natural terphenyls are p-terphenyl derivatives consisting of a C-18 tricyclic or polycyclic C-18 aromatic skeleton. Diarylcyclopentenones, which possess a

Electrochemical and spectroscopic properties of twisted dibenzo[g,p]chrysene derivatives

• Tomoya Imai,
• Ryuhei Akasaka,
• Naruhiro Yoshida,
• Toru Amaya and
• Tetsuo Iwasawa

Beilstein J. Org. Chem. 2022, 18, 963–971, doi:10.3762/bjoc.18.96

• , a strong photoluminescence was observed for DBC-H and DBC-Si. Keywords: DFT calculation; dibenzo[g,p]chrysenes; fluorescent compounds; oxidation; polycyclic aromatic hydrocarbon (PAH); twisted acenes; Introduction Polycyclic aromatic hydrocarbons (PAHs) have attracted interest as potential

Morita–Baylis–Hillman reaction of 3-formyl-9H-pyrido[3,4-b]indoles and fluorescence studies of the products

• Nisha Devi and
• Virender Singh

Beilstein J. Org. Chem. 2022, 18, 926–934, doi:10.3762/bjoc.18.92

• and substituents was also studied during investigation of fluorescence properties of these derivatives. Keywords: β-carboline; DABCO; fluorescence; MBH reaction; Michael addition; structure–fluorescence activity relationship; Introduction Among the polycyclic alkaloids based on indole, the tricyclic

Efficient production of clerodane and ent-kaurane diterpenes through truncated artificial pathways in Escherichia coli

• Fang-Ru Li,
• Xiaoxu Lin,
• Qian Yang,
• Ning-Hua Tan and
• Liao-Bin Dong

Beilstein J. Org. Chem. 2022, 18, 881–888, doi:10.3762/bjoc.18.89

• categories of diterpenoid natural products with complicated polycyclic carbon skeletons and significant pharmacological activities. Despite exciting advances in organic chemistry, access to these skeletons is still highly challenging. Using synthetic biology to engineer microbes provides an innovative

• group or a combination of enzymatic and chemical tools (chemoenzymatic synthesis) [8][9][10][11]. Despite great efforts spanning several decades, de novo organic synthetic methods access to the core diterpene skeletons are still highly challenging owing to their numerous chiral centers and polycyclic

Copper-catalyzed multicomponent reactions for the efficient synthesis of diverse spirotetrahydrocarbazoles

• Shao-Cong Zhan,
• Ren-Jie Fang,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 796–808, doi:10.3762/bjoc.18.80

• this respect, Lévy reported a copper-catalyzed three-component reaction of aromatic aldehydes, ethyl indole-2-acetate and N-alkylmaleimides for the efficient construction of polycyclic tetrahydrocarbazoles, in which indolo-2,3-quinodimethane intermediate was initially generated and sequentially

Synthesis of odorants in flow and their applications in perfumery

• Merlin Kleoff,
• Paul Kiler and
• Philipp Heretsch

Beilstein J. Org. Chem. 2022, 18, 754–768, doi:10.3762/bjoc.18.76

• iron (Habanolide, (12E)-oxacyclohexadec-12-en-2-one) [3][4][9][46][47]. Although, all musks of natural origin are macrocyles, most synthetic musks are polycyclic musks (PCM), while the fourth synthetic generation of musks are linear molecules [3][4]. In 1999, juniper lactone (56) was isolated from the

Complementarity of solution and solid state mechanochemical reaction conditions demonstrated by 1,2-debromination of tricyclic imides

• Petar Štrbac and
• Davor Margetić

Beilstein J. Org. Chem. 2022, 18, 746–753, doi:10.3762/bjoc.18.75

• Petar Strbac Davor Margetic Ruđer Bošković Institute, Bijenička cesta 54, HR-10002 Zagreb, Croatia 10.3762/bjoc.18.75 Abstract The solution phase 1,2-debromination of polycyclic imides using the Zn/Ag couple was successfully transferred to solid state mechanochemical conditions. The Zn/Ag couple

• polycyclic molecules given in Figure 1 are interesting reactive intermediates which could be applied in the Diels−Alder reactions of less reactive or thermally susceptible dienes. Often, these are generated in situ and trapped with dienes in a single pot, such as 7-oxanorbornadiene imides 1–3. For instance

• , Cycloaddition strategies towards polycyclic guanidines (CycloGu)). Poster presented at the ACS 25th Annual Green Chemistry & Engineering Conference, June 14-18, 2021.

Tri(n-butyl)phosphine-promoted domino reaction for the efficient construction of spiro[cyclohexane-1,3'-indolines] and spiro[indoline-3,2'-furan-3',3''-indolines]

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

Beilstein J. Org. Chem. 2022, 18, 669–679, doi:10.3762/bjoc.18.68

• respect, we have also developed several domino reactions by employing tertiary phosphine addition to electron-deficient alkynes as key protocol for the construction of diverse polycyclic spirooxindoles [53][54][55][56][57][58][59]. In continuation of our aim to explore elegant domino reactions for spiro

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

• ]indolylvincoside 12 (de = 85%) [14]. In situ lactamization of 12 under basic conditions (10% Na2CO3) generated stable polycyclic compound 13 in 70% yield (Scheme 5A). In a separate report published in 2020, the same research group disclosed that water could act as both catalyst and solvent in the Pictet−Spengler

• 18 via a concerted protonation and C–C bond formation. Weakened dispersive interactions caused by a substituent or heteroatom resulted in low yields and reduced regioselectivities. In 2020, Li and Van der Eycken and co-workers reported the synthesis of densely functionalized, polycyclic azepino[5,4,3

• cyclization leading to the formation of polycyclic azepino[5,4,3-cd]indoles. Synthesis of azepino[3,4,5-cd]indoles via iridium-catalyzed asymmetric [4 + 3] cycloaddition of racemic 4-indolyl allylic alcohols with azomethine ylides. Aldimine condensation/1,6-hydride transfer/Mannich-type cyclization cascade of

1,2-Naphthoquinone-4-sulfonic acid salts in organic synthesis

• Ruan Carlos B. Ribeiro,
• Patricia G. Ferreira,
• Amanda de A. Borges,
• Luana da S. M. Forezi,
• Fernando de Carvalho da Silva and
• Vitor F. Ferreira

Beilstein J. Org. Chem. 2022, 18, 53–69, doi:10.3762/bjoc.18.5

• catecholamines and other compounds, but they can also be ingested as exogenous products of air and water. The most common quinones, such as benzoquinone, naphthoquinone, anthraquinone, and phenanthrenequinone, can be formed by incomplete combustion or photooxidation of their respective polycyclic aromatic

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

• alkylidenecyclopropanes 142 for the synthesis of polycyclic benzazepine derivatives 144 (Scheme 29) [123]. The authors noted electron-withdrawing substituents were detrimental to the efficacy of the reaction with electron-withdrawing N-substituents failing to react. When a methoxy group was installed at the para-position

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

• fused polycyclic ethers by the treatment of a catalytic amount of Hg(TFA)2 with suitable starting material was demonstrated by Tan et al. [89]. They had reported a Hg(II)-catalyzed intramolecular trans-etherification reaction of 2-hydroxy-1-(γ-methoxyallyl)tetrahydropyrans 118 and 120 to the

• vinylmercury intermediate (Scheme 55). For the synthesis of stereoselective tetrahydropyran derivatives 184, Hg(II)-catalyzed cyclization proved to be more effective than silver(I)-salt-mediated cyclization. It showed that methyl-substituted allenes undergo efficient cyclization to form polycyclic ethers under

Transition-metal-free intramolecular Friedel–Crafts reaction by alkene activation: A method for the synthesis of some novel xanthene derivatives

• Tülay Yıldız,
• İrem Baştaş and
• Hatice Başpınar Küçük

Beilstein J. Org. Chem. 2021, 17, 2203–2208, doi:10.3762/bjoc.17.142

• of their important biological and fluorescent uses. To summarize the main syntheses of these studies: in particular, transition metal-catalyzed cascade benzylation–cyclization [17], cyclization of polycyclic aryl triflate esters [18], reaction of β-naphthol and aldehydes [19][20] or inter- or

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

• although they are classified in other categories that are also appropriate. Takai, Kuninobu, and their research group used an indium catalyst to synthesize polycyclic aromatic compounds via a reductive-dehydration intramolecular cycloaromatization [51], which is a Bradsher-type reaction. The authors

• to obtain polycyclic aza-aromatic compounds. They achieved promising results and obtained the aza-analogue acridine (79) from 2-(phenylamino)benzaldehyde (78) in excellent yield (97%) [51]. In 2012, Balczewski and co-workers reported a new methodology to synthesize 10-OR-substituted anthracenes 82

• internal alkynes, have been the most used, possibly because they provide a simple and straightforward ring extension method to construct polycyclic aromatic compounds, especially anthracenes with substituents in the 2-, 3-, 6-, and 7-positions. Also, considering the difficulties and limitations of direct

Progress and challenges in the synthesis of sequence controlled polysaccharides

• Giulio Fittolani,
• Theodore Tyrikos-Ergas,
• Denisa Vargová,
• Manishkumar A. Chaube and
• Martina Delbianco

Beilstein J. Org. Chem. 2021, 17, 1981–2025, doi:10.3762/bjoc.17.129

• for the introduction of unnatural modifications. However, the control over the length and substitution pattern remains poor. To ensure good regio- and stereoselectivity, the starting material, often a polycyclic compound, has to be designed with suitable protecting groups (PGs). These structures can

Asymmetric organocatalyzed synthesis of coumarin derivatives

• Natália M. Moreira,
• Lorena S. R. Martelli and
• Arlene G. Corrêa

Beilstein J. Org. Chem. 2021, 17, 1952–1980, doi:10.3762/bjoc.17.128

• proposed transition state includes activations of the enone via an iminium ion and the coumarin by hydrogen bonding. A series of optically active polycyclic pyranocoumarin derivatives 37 was obtained in high yields with excellent enantioselectivities (up to 97% ee) (Scheme 12). Kowalczyk and Albrecht

• -hydroxycoumarin 1 with α,β-unsaturated ketones 2 catalyzed by a chiral primary amino amide 32. Catalytic asymmetric β-C–H functionalization of ketones via enamine oxidation. Enantioselective synthesis of polycyclic coumarin derivatives 37 catalyzed by an primary amine-imine catalyst 38. Allylic alkylation

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

• amino acids and peptide scaffolds compatible with the transformation. The late-stage oxidation of proline 76 to 5-hydroxyproline furnished interesting intermediates, giving access to relevant motifs in peptide chemistry (Scheme 27C). Sesquiterpenes are known to present complex polycyclic structures with

Development of N-F fluorinating agents and their fluorinations: Historical perspective

• Teruo Umemoto,
• Yuhao Yang and
• Gerald B. Hammond

Beilstein J. Org. Chem. 2021, 17, 1752–1813, doi:10.3762/bjoc.17.123

• powerful fluorinating agent with a high fluorine content, F: 103 g/1 kg (comparison; 54 g/1 kg for Selectfluor). 1-25. N-Fluoro-2,4-dinitroimidazole In 1998, Laali et al. reported the fluorination of polycyclic aromatic hydrocarbons (PAHs) with N-fluoro-2,4-dinitroimidazole (25-1) [87] (Scheme 56). This

• . attempted to fluorinate some polycyclic aromatics with Selectfluor, but intractable mixtures were obtained. Thus, they examined the utility of 25-1 in the fluorination of polycyclic aromatics. Although a detailed optimization was conducted, the fluorination of over 20 polycyclic aromatics was poor giving

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

• −Miyaura cross-coupling produced a series of 5-aryl-4-ethynyl triazoles 136 in the presence of Pd(PPh3)4 as catalyst and K3PO4 as base in 1,4-dioxane as solvent at 100 °C (Scheme 39) [62]. A paper by Sekar et al. described the synthesis of polycyclic triazoles 142 through a domino alkyne insertion and C–H

• ) tetrafluoroborate (138) in the presence of HBF4 and NaNO2 at 0 °C. Next, the nanoparticles were obtained from the reduction of Pd(OAc)2 and Cu(OAc)2 employing NaBH4 in the presence of diazonium salt [63]. A possible mechanism for the synthesis of polycyclic triazoles 142 was proposed by Sekar et al. as well [63

Methodologies for the synthesis of quaternary carbon centers via hydroalkylation of unactivated olefins: twenty years of advances

• Thiago S. Silva and
• Fernando Coelho

Beilstein J. Org. Chem. 2021, 17, 1565–1590, doi:10.3762/bjoc.17.112

• radical conjugate addition triggered by the HAT process (see Scheme 22 intermediate D) allowed the construction of complex polycyclic units containing quaternary carbon centers. In the first case, a cascade radical addition/conjugate addition promoted by a HAT process to the terminal olefin of 53 (Scheme