Synthesis of the tetracyclic skeleton of Aspidosperma alkaloids via PET-initiated cationic radical-derived interrupted [2 + 2]/retro-Mannich reaction

• Ru-Dong Liu,
• Jian-Yu Long,
• Zhi-Lin Song,
• Zhen Yang and
• Zhong-Chao Zhang

Beilstein J. Org. Chem. 2025, 21, 2470–2478, doi:10.3762/bjoc.21.189

• concerted nor stepwise. These findings shed light on the mechanistic innovation of a PET-initiated radical-derived reaction that was driven by the ring-strain release. Synthetic plan. a) General model of cyclobutenone bond cleavage; b) our previously reported method; c) plan for indole Aspidosperma alkaloid

Transformation of the cyclohexane ring to the cyclopentane fragment of biologically active compounds

• Natalya Akhmetdinova,
• Ilgiz Biktagirov and
• Liliya Kh. Faizullina

Beilstein J. Org. Chem. 2025, 21, 2416–2446, doi:10.3762/bjoc.21.185

• octahydrophenanthrene, is a natural follicular hormone essential for normal development of the female body [6]. An example of an alkaloid whose structure includes cyclopentane is lappaconitine, which is noteworthy because its hydrobromide is the active ingredient in the highly effective antiarrhythmic drug allapinine

• obtaining medically interesting dactylicapnosine-like analogues for detailed study of their biological activity. Matoba et al. [45] reported the first enantioselective synthesis of the hasubanane alkaloid (−)-metaphanine (70) and the norhasubanane alkaloid (+)-stephadiamine (71) using a cyclohexane ring

• in the stabilization of cationic reaction intermediates [91][92]. Yokoshima and co-workers [93][94] developed an elegant approach to the total synthesis of the alkaloid huperzine Q (206) in racemic form (Scheme 37). In the process of synthesis, a cis-hydrindane core was prepared from the known

Comparative analysis of complanadine A total syntheses

• Reem Al-Ahmad and
• Mingji Dai

Beilstein J. Org. Chem. 2025, 21, 2334–2344, doi:10.3762/bjoc.21.178

• compare four total syntheses of complanadine A, a complex and pseudo-dimeric lycopodium alkaloid with promising neurotrophic activity and potential for pain management. These four total syntheses are from the groups of Siegel, Sarpong, Tsukano, and Dai. Each of the four total syntheses contains innovative

• strategies and creative tactics, reflecting how emerging synthetic capabilities and concepts can positively impact natural product total synthesis. Keywords: biomimetic synthesis; C–H functionalization; complanadine; lycopodium alkaloid; skeletal editing; total synthesis; transition metal catalysis

Pathway economy in cyclization of 1,n-enynes

• Hezhen Han,
• Wenjie Mao,
• Bin Lin,
• Maosheng Cheng,
• Lu Yang and
• Yongxiang Liu

Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173

• controllable cyclization of tryptamine-derived ynamides to synthesize two types of indole alkaloid skeletons (Scheme 13) [20]. For alkyl-substituted alkynes, the ynamide activated by BiCl3 was attacked by indole's C3-position to form spirocyclic intermediate 58. Subsequent 1,2-migration then exclusively

• structures, demonstrating notable utility in the synthesis of this biologically significant alkaloid. In 2020, Sanz and co-workers developed a gold(I)-catalyzed strategy achieving stereoselective construction of alkylidenecyclopentenes and benzene derivatives (Scheme 31) [44]. Notably, this study pioneered

The application of desymmetric enantioselective reduction of cyclic 1,3-dicarbonyl compounds in the total synthesis of terpenoid and alkaloid natural products

• Dong-Xing Tan and
• Fu-She Han

Beilstein J. Org. Chem. 2025, 21, 2085–2102, doi:10.3762/bjoc.21.164

• synthesis of complex terpenoid and alkaloid natural products by strategically applying desymmetric enantioselective reduction. Advance before 2016 in this area has been overviewed in an elegant review article. Since then, a series of more challenging terpenoid and alkaloid natural products have been

• synthesized utilizing a desymmetric enantioselective reduction strategy of cyclic 1,3-dicarbonyl compounds as a key transformation. This review will summarize the application of this strategy in the total synthesis of terpenoid and alkaloid natural products from the year 2016 to 2025. We first focus on the

• shortage of natural product sources. Nevertheless, the asymmetric total synthesis of terpenoid and alkaloid natural products presents significant challenges due to their complex and diverse ring systems and the presence of multiple stereocenters, including all-carbon quaternary stereocenters. Consequently

Further elaboration of the stereodivergent approach to chaetominine-type alkaloids: synthesis of the reported structures of aspera chaetominines A and B and revised structure of aspera chaetominine B

• Jin-Fang Lü,
• Jiang-Feng Wu,
• Jian-Liang Ye and
• Pei-Qiang Huang

Beilstein J. Org. Chem. 2025, 21, 2072–2081, doi:10.3762/bjoc.21.162

• . The former was demonstrated by the synthesis of alkaloid 14-epi-isochaetominine C that was used to determine the enantiomeric excess of the synthesized natural product (98.7% ee), while the latter was illustrated by the synthesis of both enantiomers of the alkaloid isochaetominine. Additionally, the

• ][49][50][51][52][53][54]. This is the case for (−)-chaetominine (1 in Figure 1), which is a hexacyclic quinazolinone alkaloid possessing four stereogenic centers, first isolated from a solid-substrate culture of Chaetomium sp. IFB-E015 [21]. Subsequently, several homologues, diastereomers, and

• -workers [21], its synthesis has attracted attention of the synthetic community. The group of Snider [47], Evano [48][49], and Papeo [50] reported several elegant highly enantio- and diastereoselective total syntheses of this alkaloid from ᴅ-tryptophan. With our longstanding interest in the efficient total

Discovery of cytotoxic indolo[1,2-c]quinazoline derivatives through scaffold-based design

• Daniil V. Khabarov,
• Valeria A. Litvinova,
• Lyubov G. Dezhenkova,
• Dmitry N. Kaluzhny,
• Alexander S. Tikhomirov and
• Andrey E. Shchekotikhin

Beilstein J. Org. Chem. 2025, 21, 2062–2071, doi:10.3762/bjoc.21.161

• (5) (Scheme 1), a structural analogue of the biologically active alkaloid tryptanthrin (Figure 1). An alternative scheme to indolo[1,2-c]quinazoline-12-carboxylic acid (3) was based on initial acylation followed by a haloform reaction. Refluxing compound 1 with trifluoroacetic anhydride (TFAA) in

• – the alkaloid tryptanthrin [17], indicating the importance of ring annelation sequence. In contrast, indolo[1,2-c]quinazolin-6(5H)-one (1), its unmodified 6-methyl analog 8, and 6-chloromethyl analog 13 demonstrated a more pronounced, though still moderate, effect on cell growth (Table 3). The

Enantioselective desymmetrization strategy of prochiral 1,3-diols in natural product synthesis

• Lihua Wei,
• Rui Yang,
• Zhifeng Shi and
• Zhiqiang Ma

Beilstein J. Org. Chem. 2025, 21, 1932–1963, doi:10.3762/bjoc.21.151

• ]. Snyder and co-workers applied this method to synthesize arboridinine, an indole alkaloid isolated from a Malaysian Kopsia species (Scheme 24) [66]. The synthesis commenced with tert-butyloxycarbonyl (Boc)-protected tryptamine 181, which was converted into diol 182 in two steps. Initial attempts to forge

Preparation of spirocyclic oxindoles by cyclisation of an oxime to a nitrone and dipolar cycloaddition

• Beth L. Ritchie,
• Alexandra Longcake and
• Iain Coldham

Beilstein J. Org. Chem. 2025, 21, 1890–1896, doi:10.3762/bjoc.21.146

• ]. Representative examples are shown in Figure 1. The alkaloid alstonisine has antimalarial activity, with IC50 7.6 μM against Plasmodium falciparum [5]. However, the biological activities of most of the Alstonia alkaloids are currently unknown, despite the potential of spirooxindoles for drug discovery [6]. This

Convenient alternative synthesis of the Malassezia-derived virulence factor malassezione and related compounds

• Karu Ramesh and
• Stephen L. Bearne

Beilstein J. Org. Chem. 2025, 21, 1730–1736, doi:10.3762/bjoc.21.135

• are commensal fungi that constitute the normal skin microbiota but may become pathogenic. These fungi, especially M. furfur, convert tryptophan into various alkaloid indoles such as malassezione, which may serve as virulence factors. To facilitate testing of malassezione as an aryl hydrocarbon

• neurological disorders [7] and possibly other non-skin diseases [5]. These fungi, especially M. furfur, convert tryptophan into various alkaloid indoles such as malassezione (1), malassezin (2), which cyclizes to indolo[3,2-b]carbazole (3), other related indolo[3,2-b]carbazoles (4–7), pityriarubins (8–10), and

Recent total synthesis of natural products leveraging a strategy of enamide cyclization

• Chun-Yu Mi,
• Jia-Yuan Zhai and
• Xiao-Ming Zhang

Beilstein J. Org. Chem. 2025, 21, 999–1009, doi:10.3762/bjoc.21.81

• particular emphasis on their pivotal role as a strategy in the total synthesis of natural products. Keywords: alkaloid; cyclization; enamide; natural product; total synthesis; Introduction The use of enamines as surrogates for enols in nucleophilic reactions has been well-documented for decades since their

• on this strategy, the authors also accomplished the total synthesis of (−)-lycospidine A in only 10 steps [20], another Lycopodium alkaloid with a truncated tetracyclic skeleton and distinct oxidation levels, further highlighting the versatility and efficiency of the enamide aza-Prins approach

• total synthesis of cephalotaxine. Similarly, diastereoselective reduction of 25 with KBH4 followed by alane reduction provided another alkaloid cephalezomine H. Collective total syntheses of Cephalotaxus alkaloids The cyclopentane ring in most Cephalotaxus alkaloids is characterized by the highest

Studies on the syntheses of β-carboline alkaloids brevicarine and brevicolline

• Benedek Batizi,
• Patrik Pollák,
• András Dancsó,
• Péter Keglevich,
• Gyula Simig,
• Balázs Volk and
• Mátyás Milen

Beilstein J. Org. Chem. 2025, 21, 955–963, doi:10.3762/bjoc.21.79

• , Semmelweis University, Üllői út 26, H-1085 Budapest, Hungary 10.3762/bjoc.21.79 Abstract A new total synthesis of the β-carboline alkaloid brevicarine is disclosed. The synthesis was carried out starting from an aromatic triflate key intermediate, allowing the introduction of various substituents into

• salt for further confirming their structures. A new synthesis of the related alkaloid brevicolline was also attempted from the same intermediate. However, after successful coupling of β-carboline with N-methylpyrrole, the trials to saturate the pyrrole ring under various conditions led to unexpected

• reactions: reduction of ring A of the β-carboline skeleton or trifluoroethylation of the pyrrole moiety occurred, leading to interesting and potentially useful derivatives. Keywords: alkaloid; β-carboline; Carex brevicollis DC; cross-coupling reaction; trifluoroethylation; Introduction Carex brevicollis

New advances in asymmetric organocatalysis II

• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 766–769, doi:10.3762/bjoc.21.60

• describes the enantioselective Michael addition of pyrazoline-5-ones to α,β-unsaturated ketones. The enantioselectivity and chemical efficiency of this transformation were achieved with a cinchona-alkaloid-derived primary-amine–Brønsted acid composite [22]. A good demonstration of how organocatalysis

Origami with small molecules: exploiting the C–F bond as a conformational tool

• Patrick Ryan,
• Ramsha Iftikhar and
• Luke Hunter

Beilstein J. Org. Chem. 2025, 21, 680–716, doi:10.3762/bjoc.21.54

Streamlined modular synthesis of saframycin substructure via copper-catalyzed three-component assembly and gold-promoted 6-endo cyclization

• Asahi Kanno,
• Ryo Tanifuji,
• Satoshi Yoshida,
• Sota Sato,
• Saori Maki-Yonekura,
• Kiyofumi Takaba,
• Jungmin Kang,
• Kensuke Tono,
• Koji Yonekura and
• Hiroki Oguri

Beilstein J. Org. Chem. 2025, 21, 226–233, doi:10.3762/bjoc.21.14

• involvement of a fluorescent intermediate in the cascade synthetic process. Keywords: cascade reactions; copper-catalyzed three-component coupling; gold-mediated 6-endo hydroamination; tandem cyclizations; tetrahydroisoquinoline alkaloids; Introduction The bis-tetrahydroisoquinoline (THIQ) alkaloid family

• represented by saframycin A (1) and ecteinascidin 743 (2) shares a complex penta- or hexacyclic core skeleton composed of two THIQ units (Figure 1) [1][2][3][4][5]. As proven by the clinical use of compound 2 for the treatment of malignant soft tissue sarcomas, the bis-THIQ alkaloid family exhibits potent

Recent advances in organocatalytic atroposelective reactions

• Henrich Szabados and
• Radovan Šebesta

Beilstein J. Org. Chem. 2025, 21, 55–121, doi:10.3762/bjoc.21.6

Non-covalent organocatalyzed enantioselective cyclization reactions of α,β-unsaturated imines

• Sergio Torres-Oya and
• Mercedes Zurro

Beilstein J. Org. Chem. 2024, 20, 3221–3255, doi:10.3762/bjoc.20.268

• -workers reported a cinchona alkaloid-derived thiourea-catalyzed regio- and stereoselective cycloaddition of 3-isothiocyanatooxindoles and imines containing two or three electron-deficient unsaturated bonds [25]. Firstly, the (3 + 2) cycloaddition of 3-isothiocyanatooxindoles 4 and aldimines 5 was explored

• utilized for a wide variety of organocatalytic processes. In this section, different cyclizations of α,β-unsaturated imines involving Brønsted base organocatalysts such as (DHQD)2-based catalysts will be described. In 2015, Jiang, Chen and co-worker published a modified cinchona alkaloid-catalyzed [4 + 2

• alkaloid and (DHQD)2PHAL. Enantioselective bifunctional thiourea-catalyzed inverse electron demand Diels–Alder reaction of N-tosyl-2-methylene-but-3-enoates and cyclic keto/enolate salts. Cinchona-derived thiourea-catalyzed stereoselective (3 + 2) reaction of α,β-unsaturated imines and 3

Asymmetric organocatalytic synthesis of chiral homoallylic amines

• Nikolay S. Kondratyev and
• Andrei V. Malkov

Beilstein J. Org. Chem. 2024, 20, 2349–2377, doi:10.3762/bjoc.20.201

• process and the rich toolkit of advanced organic synthesis [5]. Homoallylic amines occupy a significant niche in alkaloid synthesis as they frequently appear as key intermediates in syntheses of the various nitrogen-containing natural products [6][7][8][9][10][11][12][13][14]. Additionally, they can be

• mechanism is energetically more favoured [34]. Two computed reaction pathways for the COBI-catalysed Strecker reaction (TS1 identical to allylation – COBI–imine complex) reported by Chen and Qiao in 2023 [38]. The position of homoallylic amines in the landscape of alkaloid and nitrogen compounds syntheses

Stereoselective mechanochemical synthesis of thiomalonate Michael adducts via iminium catalysis by chiral primary amines

• Michał Błauciak,
• Dominika Andrzejczyk,
• Błażej Dziuk and
• Rafał Kowalczyk

Beilstein J. Org. Chem. 2024, 20, 2313–2322, doi:10.3762/bjoc.20.198

• , changes in the epi-amino alkaloid core of the two-component catalytic system were investigated. Introduction of the 2’-substitution to the quinine core as in AQ-2 and AQ-4 (Scheme 2) resulted in the decrease of chirality transfer providing the product with 50% and 72% ee, respectively. A similar trend was

Factors influencing the performance of organocatalysts immobilised on solid supports: A review

• Zsuzsanna Fehér,
• Dóra Richter,
• Gyula Dargó and
• József Kupai

Beilstein J. Org. Chem. 2024, 20, 2129–2142, doi:10.3762/bjoc.20.183

• organocatalyst was demonstrated by List and co-workers, who showcased the robustness of a cinchona alkaloid-based sulfonamide organotextile catalyst 36 (immobilised on nylon 6,6) through hundreds of recycling experiments (Scheme 11) [15]. The organotextile catalyst 36 exhibited a very similar enantioselectivity

Solvent-dependent chemoselective synthesis of different isoquinolinones mediated by the hypervalent iodine(III) reagent PISA

• Ze-Nan Hu,
• Yan-Hui Wang,
• Jia-Bing Wu,
• Ze Chen,
• Dou Hong and
• Chi Zhang

Beilstein J. Org. Chem. 2024, 20, 1914–1921, doi:10.3762/bjoc.20.167

• activity and thus block cancer formation [2]. Alangiumkaloids A, an isoquinolinone alkaloid isolated from Alangium salviiforlium, was reported to exhibit cytotoxic activity against cancer cells [3]. In 2018, duvelisib, a dual inhibitor of phosphoinositide-3 kinases, was firstly approved by the FDA for the

Chemo-enzymatic total synthesis: current approaches toward the integration of chemical and enzymatic transformations

• Ryo Tanifuji and
• Hiroki Oguri

Beilstein J. Org. Chem. 2024, 20, 1693–1712, doi:10.3762/bjoc.20.151

• . Iterative Pictet–Spengler cyclizations: saframycin A and jorunnamycin A Saframycin A (5) was isolated from Streptomyces lavendulae, and a number of related alkaloid families such as safracins and renieramycins have been identified from both soil and marine microorganisms [89][90]. These natural product

• synthesis of the bis-THIQ alkaloid family, Oguri and Oikawa utilized the NRPS module SfmC to construct a highly functionalized scaffold from amino acid derivatives (Scheme 10) [102]. The total synthesis of 5 from original biosynthetic intermediate 93 requires regioselective amide bond cleavage to remove the

• place of ʟ-alanine in 88 to the SfmC-catalyzed chemo-enzymatic process [107]. The key enzyme SfmC tolerated all the synthetic analogs of the biosynthetic intermediate 88 and facilitated the rapid synthesis of non-natural bis-THIQ alkaloid-like scaffolds such as 106, 107 (Scheme 10B). The essence of this

Polymer degrading marine Microbulbifer bacteria: an un(der)utilized source of chemical and biocatalytic novelty

• Weimao Zhong and
• Vinayak Agarwal

Beilstein J. Org. Chem. 2024, 20, 1635–1651, doi:10.3762/bjoc.20.146

• Gram-positive bacteria Kocuria rhizophila and S. aureus, Gram-negative bacterium Tenacibaculum maritimum, and a panel of fungi. These molecules also demonstrated moderate cytotoxicity against P388 murine leukemia cells. The bisindole alkaloid violacein (24, Figure 8) was isolated and characterized from

Mining raw plant transcriptomic data for new cyclopeptide alkaloids

• Draco Kriger,
• Michael A. Pasquale,
• Brigitte G. Ampolini and
• Jonathan R. Chekan

Beilstein J. Org. Chem. 2024, 20, 1548–1559, doi:10.3762/bjoc.20.138

• cyclopeptide alkaloids due to the invariant C-terminal Tyr residue (Figure 3). Rubiaceae family Our previous results revealed Coffea arabica (Arabica coffee plant), to be a cyclopeptide alkaloid producer [7]. In contrast to those from the Rhamnaceae family, these cyclopeptide alkaloids were only cyclized and

• additional plant species may be responsible for the production of burpitides. To evaluate this, we examined G. jasminoides and A. bettzickiana from the Rubiaceae and Amaranthaceae families, respectively. We analyzed methanol extracts of these plants along with the known cyclopeptide alkaloid producer C

Primary amine-catalyzed enantioselective 1,4-Michael addition reaction of pyrazolin-5-ones to α,β-unsaturated ketones

• Pooja Goyal,
• Akhil K. Dubey,
• Raghunath Chowdhury and
• Amey Wadawale

Beilstein J. Org. Chem. 2024, 20, 1518–1526, doi:10.3762/bjoc.20.136

• 10.3762/bjoc.20.136 Abstract The enantioselective 1,4-addition reaction of pyrazolin-5-ones to α,β-unsaturated ketones catalyzed by a cinchona alkaloid-derived primary amine–Brønsted acid composite is reported. Both enantiomers of the anticipated pyrazole derivatives were obtained in good to excellent

• metal catalytic conditions. In continuation of our work in the field of organocatalysis [26][27][28][29], herein, we present the Michael addition reaction of 4-unsubstituted pyrazolin-5-ones with arylidene/heteroarylideneacetones using cinchona alkaloid-derived primary amine catalysts. The developed