Structural basis for endoperoxide-forming oxygenases

• Takahiro Mori and
• Ikuro Abe

Beilstein J. Org. Chem. 2022, 18, 707–721, doi:10.3762/bjoc.18.71

• endoperoxide containing alkaloids, terpenoids, and polyketides have been isolated from plants, animals, bacteria, fungi, and other organisms (Figure 1) [6][7]. Because of the high reactivity of the cyclic peroxide O–O bond, these compounds exhibit various biological activities [1][2][3][4][5]. For example

Sesquiterpenes from the soil-derived fungus Trichoderma citrinoviride PSU-SPSF346

• Wiriya Yaosanit,
• Vatcharin Rukachaisirikul,
• Souwalak Phongpaichit,
• Sita Preedanon and
• Jariya Sakayaroj

Beilstein J. Org. Chem. 2022, 18, 479–485, doi:10.3762/bjoc.18.50

• Trichoderma citrinoviride produces structurally diverse secondary metabolites including diterpenes [1][2], alkaloids [3], sorbicillinoids [4][5], long chain alcohols [6], and cyclonerane sesquiterpenes [7]. Some of them display antibacterial [1][2][7], cytotoxic [3], anti-inflammatory [4], and antimicroalgal

Unexpected chiral vicinal tetrasubstituted diamines via borylcopper-mediated homocoupling of isatin imines

• Marco Manenti,
• Leonardo Lo Presti,
• Giorgio Molteni and
• Alessandra Silvani

Beilstein J. Org. Chem. 2022, 18, 303–308, doi:10.3762/bjoc.18.34

• because they can serve as key synthetic intermediates in the construction of complex natural products [17][18][19][20][21][22][23]. Particularly challenging is the placement of the two C3/C3’ contiguous quaternary stereogenic centers, just as they are found in various alkaloids, such as those belonging to

Organocatalytic asymmetric nitroso aldol reaction of α-substituted malonamates

• Ekta Gupta,
• Narendra Kumar Vaishanv,
• Sandeep Kumar,
• Raja Krishnan Purshottam,
• Ruchir Kant and
• Kishor Mohanan

Beilstein J. Org. Chem. 2022, 18, 217–224, doi:10.3762/bjoc.18.25

• metal-catalyzed reactions [31][32][33][34][35][36]. The most successful among them are the ʟ-proline-catalyzed reactions of enolizable aldehydes with nitrosoarenes [37][38][39][40][41][42][43]. Besides ʟ-proline and its derivatives, various secondary amines derived from BINOL and cinchona alkaloids were

The PIFA-initiated oxidative cyclization of 2-(3-butenyl)quinazolin-4(3H)-ones – an efficient approach to 1-(hydroxymethyl)-2,3-dihydropyrrolo[1,2-a]quinazolin-5(1H)-ones

• Alla I. Vaskevych,
• Nataliia O. Savinchuk,
• Ruslan I. Vaskevych,
• Eduard B. Rusanov,
• Oleksandr O. Grygorenko and
• Mykhailo V. Vovk

Beilstein J. Org. Chem. 2021, 17, 2787–2794, doi:10.3762/bjoc.17.189

• Shevchenko National University of Kyiv, Kyiv 01601, Ukraine 10.3762/bjoc.17.189 Abstract A regioselective method for the synthesis of 1-(hydroxymethyl)-2,3-dihydropyrrolo[1,2-a]quinazolin-5(1H)-ones – close structural analogs of naturally occurring vasicinone alkaloids – is described. The procedure is based

• chemistry, and this approach has already provided successful results in the view of reaching biological activity. Thus, angular pyrrolo[1,2-a]quinazolines of type 1 – analogs of naturally occurring vasicinone alkaloids bearing an isomeric linear pyrrolo[2,1-b]quinazoline core [5][6][7][8] – demonstrated

• alkaloids – that can be used as building blocks to obtain natural product-like compound libraries of potential biologically active compounds. Experimental Commercially available reagents and solvents were used without further purification. The IR spectra of the compounds obtained were recorded on a Bruker

Highly stereocontrolled total synthesis of racemic codonopsinol B through isoxazolidine-4,5-diol vinylation

• Lukáš Ďurina,
• Anna Ďurinová,
• František Trejtnar,
• Ľuboš Janotka,
• Lucia Messingerová,
• Jana Doháňošová,
• Ján Moncol and
• Róbert Fischer

Beilstein J. Org. Chem. 2021, 17, 2781–2786, doi:10.3762/bjoc.17.188

• evaluated using several cell line models. Keywords: alkaloids; antiproliferative effect; codonopsinol B; diastereoselectivity; pyrrolidines; Introduction Codonopsinol B (1) is a polyhydroxylated pyrrolidine alkaloid isolated from the roots of the plant Codonopsis pilosula (Figure 1) [1]. This compound was

• . Codonopsinol B, together with its N-nor-methyl analogue 2, proved to be a potent α-glucosidase inhibitor (Figure 1). The potency it showed is higher than that of the known natural alkaloids such as radicamines A and B [3][4], and codonopsinol [5]. In contrast, the unnatural enantiomers of 1 and radicamine A

• pyrrolidine alkaloids, namely codonopsinol A and C, codonopiloside A, codonopyrrolidium B, and radicamine A, have been isolated from C. pilosula [1]. Its fresh or dried roots are generally considered as famous herbal medicines and are a part of Radix Codonopsis (together with C. pilosula var. modesta and C

The ethoxycarbonyl group as both activating and protective group in N-acyl-Pictet–Spengler reactions using methoxystyrenes. A short approach to racemic 1-benzyltetrahydroisoquinoline alkaloids

• Marco Keller,
• Karl Sauvageot-Witzku,
• Franz Geisslinger,
• Nicole Urban,
• Michael Schaefer,
• Karin Bartel and
• Franz Bracher

Beilstein J. Org. Chem. 2021, 17, 2716–2725, doi:10.3762/bjoc.17.183

• the total syntheses of 10 alkaloids in racemic form. Major advantages are a) using ω-methoxystyrenes as convenient alternatives to arylacetaldehydes, and b) using the ethoxycarbonyl residue for both activating the arylethylamine precursors for the cyclization reaction, and, as a significant extension

• (treatment with excess methyllithium) to give the corresponding alkaloids with free N–H function. This dual use of the ethoxycarbonyl group shortens the synthetic routes to hydroxylated 1-benzyltetrahydroisoquinolines significantly. Not surprisingly, these ten alkaloids did not show noteworthy effects on

• relationships in this chemotype. Keywords: acyl Pictet–Spengler reaction; alkaloids; antiproliferative activity; benzyltetrahydroisoquinolines; ion channels; protective group; total synthesis; Introduction The benzylisoquinoline alkaloids are a large and diverse class of plant secondary metabolites including

Recent advances in organocatalytic asymmetric aza-Michael reactions of amines and amides

• Pratibha Sharma,
• Raakhi Gupta and
• Raj K. Bansal

Beilstein J. Org. Chem. 2021, 17, 2585–2610, doi:10.3762/bjoc.17.173

• asymmetric aza-MR. Thus, the review includes the examples wherein cinchona alkaloids, squaramides, chiral amines, phase-transfer catalysts and chiral bifunctional thioureas have been used, which activate the substrates through hydrogen bond formation. Most of these reactions are accompanied by high yields

• compounds; however, in order to comply with the requirements of a mini review, additions of amines and amides only will be included. 1. Non-covalent bonding organocatalytic aza-Michael reactions Organocatalysts catalyzing aza-MRs through mainly hydrogen bonding include cinchona alkaloids, squaramide

• derivatives, phase-transfer catalysts and bifunctional thiourea derivatives. 1.1 Reactions catalyzed by chiral cinchona alkaloid derivatives Cai et al. prepared and used a number of organocatalysts from Cinchona alkaloids for the aza-MR of aniline (1) with chalcone (2) to obtain the adducts 4 in poor to very

α-Ketol and α-iminol rearrangements in synthetic organic and biosynthetic reactions

• Scott Benz and
• Andrew S. Murkin

Beilstein J. Org. Chem. 2021, 17, 2570–2584, doi:10.3762/bjoc.17.172

• biosynthesis of delitschiapyrone A could occur non-enzymatically in nature by a similar process. The final example of a tandem reaction involving an α-ketol rearrangement in a total synthesis was employed by Chen et al. in the preparation of (±)-securinine (54) and (±)-allosecurinine (55), biological alkaloids

Silica gel and microwave-promoted synthesis of dihydropyrrolizines and tetrahydroindolizines from enaminones

• Robin Klintworth,
• Garreth L. Morgans,
• Stefania M. Scalzullo,
• Charles B. de Koning,
• Willem A. L. van Otterlo and
• Joseph P. Michael

Beilstein J. Org. Chem. 2021, 17, 2543–2552, doi:10.3762/bjoc.17.170

• ; tetrahydroindolizines; Introduction Partially or fully saturated variants of the pyrrolizine nucleus 1 are widely occurring motifs in natural products. The hexahydropyrrolizine (pyrrolizidine) system, for example, forms the nucleus of literally hundreds of alkaloids, many of which have gained notoriety owing to their

• hepatotoxicity and neurological effects on livestock and humans [1][2]. The less commonly encountered 2,3-dihydro-1H-pyrrolizine framework occurs in the butterfly metabolites danaidal (2) and hydroxydanaidal (3) [3], as well as in plant alkaloids such as loroquin (4) [4] and the recently characterized

• ] and procuramine (10) [13], have also attracted attention recently. Our continuing efforts to exploit enaminones as building blocks for the synthesis of alkaloids and other nitrogen-containing heterocycles have largely concentrated on targets containing indolizidine and quinolizidine backbones [14

Synthesis of new substituted 7,12-dihydro-6,12-methanodibenzo[c,f]azocine-5-carboxylic acids containing a tetracyclic tetrahydroisoquinoline core structure

• Agnieszka Grajewska,
• Maria Chrzanowska and
• Wiktoria Adamska

Beilstein J. Org. Chem. 2021, 17, 2511–2519, doi:10.3762/bjoc.17.168

• ; cyclization; multicomponent reactions; synthetic methods; tetrahydroisoquinoline; Introduction The tetrahydroisoquinoline moiety is the key structure in large number of natural and synthetic biologically important molecules. Among them, isoquinoline alkaloids constitute a large family of natural products

• exhibiting a huge range of structural diversity and biological activity [1][2][3]. Within this family several structural motifs can be identified, for instance, the isopavines, constrained alkaloids possessing the 1,2,3,4-tetrahydroisoquinoline skeleton incorporated into the double cyclized azabicyclo[3.2.2

• significance in the central nervous system but also as a building blocks for the synthesis of alkaloids [10][11]. The classical strategy for the synthesis of dihydromethanodibenzoazocines is based on the use of N,N-dibenzylaminoacetaldehydes [8][9] and less often α-dibenzylaminoketone [12][13] derivatives in

Efficient synthesis of polyfunctionalized carbazoles and pyrrolo[3,4-c]carbazoles via domino Diels–Alder reaction

• Ren-Jie Fang,
• Chen Yan,
• Jing Sun,
• Ying Han and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2021, 17, 2425–2432, doi:10.3762/bjoc.17.159

• alkaloids and pharmacologically active compounds representing a broad spectrum of important bioactivities such as anticancer, antituberculosis, anti-protein kinase C, antipsychotic, and antioxidative activities [1][2][3][4][5]. For some examples, carprofen is a nonsteroidal anti-inflammatory pharmaceutical

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

• histrionicotoxin alkaloids 218 (Scheme 65) [127][128] and lepadoformine [129][130] were being successfully synthesized using this methodology for spirocyclic ring structure synthesis. The proposed mechanism proceeded initially with aminoketal formation by 6-exo-dig intramolecular oxymercuration, followed by

Base-free enantioselective S_N2 alkylation of 2-oxindoles via bifunctional phase-transfer catalysis

• Mili Litvajova,
• Emiliano Sorrentino,
• Brendan Twamley and
• Stephen J. Connon

Beilstein J. Org. Chem. 2021, 17, 2287–2294, doi:10.3762/bjoc.17.146

• synthesis of a potent CRTH2 receptor antagonist. Keywords: alkylation; base-free; cinchona alkaloids; CRTH2 antagonist; hydrogen-bonding; oxindole; phase-transfer catalysis; Introduction The 2-oxindole scaffold is an important motif present in a myriad of natural products. Among 2-oxidole derivatives, 3,3

A study on selective transformation of norbornadiene into fluorinated cyclopentane-fused isoxazolines

• Zsanett Benke,
• Attila M. Remete and
• Loránd Kiss

Beilstein J. Org. Chem. 2021, 17, 2051–2066, doi:10.3762/bjoc.17.132

• of natural products (especially macrocycles) [12], alkaloids [13], amino acids and functionalized biomolecules such as peptides [14][15][16][17][18][19][20] or various drugs [21]. Due to the ring strain, bicyclic systems and derivatives, such as norbornadiene derivatives can easily be converted

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

• ammonium salts derived from cinchona alkaloids [28]. Therefore, the asymmetric synthesis of coumarin derivatives is herein presented according to the activation mode, i.e., via covalent or non-covalent bonding. Furthermore, the use of bifunctional catalysts and multicatalysis are discussed as well

• of 2-hydroxycinnamaldehydes is important for the success of the employed catalytic system. Finally, but not least, the phase-transfer chiral organocatalysts have also been highly explored [72][73]. Most of the PTCs are based on the skeletons of cinchona alkaloids and chiral binaphthyls, though, more

Regioselective N-alkylation of the 1H-indazole scaffold; ring substituent and N-alkylating reagent effects on regioisomeric distribution

• Ryan M. Alam and
• John J. Keating

Beilstein J. Org. Chem. 2021, 17, 1939–1951, doi:10.3762/bjoc.17.127

• occurring indazoles have been reported in the literature [2][3][4], such as the alkaloids nigellicine (1) and nigellidine (2), there are a myriad of synthetic indazole derivatives known that display a broad range of biological activities. For example, several N-1 and N-2-substituted indazoles are currently

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

• synthesis of the bioactive natural macrolactone (±)-decinine (30) (Scheme 11B) [96]. These compounds (26–29) derive from the class of Lythraceae alkaloids (Scheme 11A), extracted from Heimia salicifolia, and present valuable pharmacological properties, such as antisyphilitic, sudoritic, antipyretic

Natural products in the predatory defence of the filamentous fungal pathogen Aspergillus fumigatus

• Jana M. Boysen,
• Nauman Saeed and
• Falk Hillmann

Beilstein J. Org. Chem. 2021, 17, 1814–1827, doi:10.3762/bjoc.17.124

• molecules like non-ribosomal peptides (NRP), polyketides (PK), terpenes or indole alkaloids [10][11]. The vast majority of fungal BGCs is found in the genomes of members of the Basidiomycota and Ascomycota including the genus Penicillium in which the first BGC was identified in 1990 [12][13][14

• bisnaphthopyrones like aurofusarin but also Aspergillus and Penicilllium species produce these metabolites which show antifeedant effects on a wide variety of arthropods [24]. Some fungal compounds can have deleterious effects on humans, livestock or crops, like the ergot alkaloids, e.g., ergotamine (4) present in

• therapeutic potential of ergot alkaloids as early as 1582 and used it for abortion or to aid childbirth. The ecological significance of ergot alkaloids remains unclear, but they are assumed to be a feeding deterrent due to their toxicity and bad taste [25][26][27][28]. To trigger the synthesis of new SMs a

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

• reported by Banks when quinuclidine was N-fluorinated with Selectfluor [62] (Scheme 67). Subsequently, in 2001, Shibata et al. presented full details of their studies including the definitive identification of N-fluorinated cinchona alkaloids by X-ray crystallography analysis and further applications [96

• -fluoro salts of cinchona alkaloids through the reaction of the alkaloids with Selectfluor [97]. Following the precedent from Banks’s fluorine-transfer reaction from Selectfluor to the N-site of quinuclidine [62], Cahard et al. isolated four N-fluorocinchona alkaloid salts, F-CD-BF4 30-1, F-CN-BF4 30-2, F

Iodine-catalyzed electrophilic substitution of indoles: Synthesis of (un)symmetrical diindolylmethanes with a quaternary carbon center

• Thanigaimalai Pillaiyar,
• Masoud Sedaghati,
• Andhika B. Mahardhika,
• Lukas L. Wendt and
• Christa E. Müller

Beilstein J. Org. Chem. 2021, 17, 1464–1475, doi:10.3762/bjoc.17.102

• affinity; cannabinoid receptors; diindolylmethane; unsymmetrical 3,3'-diindolylmethane; Introduction Diindolylmethanes (DIMs) represent an important class of indole alkaloids, that are constituents of pharmaceuticals [1][2][3][4][5][6][7] and agrochemicals [8][9]. DIM derivatives possess a variety of

Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96

• medicinally active as well as smart functional materials possessing the pyrrole as a fundamental subunit [28][29][30]. Additionally, 3,4-disubstituted pyrrole derivatives are versatile building blocks for the production of diverse bioactive molecules like co-enzyme, alkaloids, porphyrins and other related

Icilio Guareschi and his amazing “1897 reaction”

• Gian Cesare Tron,
• Alberto Minassi,
• Giovanni Sorba,
• Mara Fausone and
• Giovanni Appendino

Beilstein J. Org. Chem. 2021, 17, 1335–1351, doi:10.3762/bjoc.17.93

• of 47. In Turin, Guareschi pursued an amazing range of research topics. The one of ptomaines (alcaloidi cadaverici, cadaverous alkaloids) and the chemistry of naphthalene led to considerable fame for Guareschi because of both his original contributions and his comprehensive reviews of the area. Thus

• considered a major cause of food poisoning, a huge problem throughout the 19th century that, as we now know, is rather associated with bacterial activity. The surprising popularity of ptomaines as research topic was also due to the forensic relevance. Thus, ptomaines yield positive test results for alkaloids

• Guareschi” [42]. Triacetonamine bears a certain similarity to tropinone (9), the heterocyclic core of tropane alkaloids, and the one-pot preparation from acetone and ammonia reminds of, and anticipates by two decades, the Robinson synthesis of tropinone and the Willstätter synthesis of the corresponding 2

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

• Guido Gambacorta,
• James S. Sharley and
• Ian R. Baxendale

Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90

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

• Orgánica (ISO), Universidad de Alicante, Apdo. 99, 03080 Alicante, Spain 10.3762/bjoc.17.86 Abstract The synthesis of nitrogen-containing heterocycles, including natural alkaloids and other compounds presenting different types of biological activities have proved to be successful employing chiral sulfinyl

• widespread use of these imines as precursors of chiral compounds with a nitrogen atom bonded to a stereogenic center. The amine derivatives, resulting after removal of the tert-butanesulfinyl group, can be transformed into enantioenriched nitrogen-containing heterocycles [6][7] including natural alkaloids [8

• -butanesulfonamide and applications in some nucleophilic additions, the next sections will describe the synthesis of several alkaloids according to the size of the heterocycles. We regret in advance that some contributions are excluded in order to maintain a concise format. Review Asymmetric synthesis of aziridines