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

• tertiary enamides is employed. Inspired by Wang’s earlier work, Zhang and Tu’s group developed a tandem cyclization/Mannich reaction to construct this architecture [35]. However, unlike the electron-rich arenes, the use of silyl enol ethers to terminate the second cyclization of the acyliminium

Asymmetric synthesis of β-amino cyanoesters with contiguous tetrasubstituted carbon centers by halogen-bonding catalysis with chiral halonium salt

• Yasushi Yoshida,
• Maho Aono,
• Takashi Mino and
• Masami Sakamoto

Beilstein J. Org. Chem. 2025, 21, 547–555, doi:10.3762/bjoc.21.43

• , which formed the corresponding products in high to excellent enantioselectivities. In this paper, the asymmetric synthesis of β-amino cyanoesters with contiguous tetrasubstituted carbon stereogenic centers by the Mannich reaction through chiral halonium salt catalysis is presented, which provided the

• corresponding products in excellent yields with up to 86% ee. To the best of our knowledge, the present paper is the first to report the asymmetric construction of β-amino cyanoesters with contiguous tetrasubstituted carbon stereogenic centers by the catalytic Mannich reaction. Keywords: asymmetric catalysis

• ; chiral halonium salt; contiguous stereocenters; halogen bonding; Mannich reaction; Introduction Halogen bonding (XB) has attracted intense research attention for its unique interaction between halogen atoms and electron-rich substituents [1]. XB has been applied to various fields of chemistry, such as

Cu(OTf)₂-catalyzed multicomponent reactions

• Sara Colombo,
• Camilla Loro,
• Egle M. Beccalli,
• Gianluigi Broggini and
• Marta Papis

Beilstein J. Org. Chem. 2025, 21, 122–145, doi:10.3762/bjoc.21.7

• . The Mannich reaction with aromatic aldehydes and cyclic amines was performed efficiently on 2-naphthol, by using SiO2-supported copper triflate under solvent-free conditions, without an additional co-catalyst or additive (Scheme 3) [17]. The treatment of stoichiometric amounts of arylaldehydes

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

• the nitrogen atoms. Then, the azlactone enolate undergoes a nucleophilic attack on its Si-face via Mannich reaction with the 2-benzothiazolimine leading to intermediate A which evolves toward its resonance form B, responsible of the intramolecular attack of the negatively charged nitrogen to the

Multicomponent synthesis of α-branched amines using organozinc reagents generated from alkyl bromides

• Baptiste Leroux,
• Alexis Beaufils,
• Federico Banchini,
• Olivier Jackowski,
• Alejandro Perez-Luna,
• Fabrice Chemla,
• Marc Presset and
• Erwan Le Gall

Beilstein J. Org. Chem. 2024, 20, 2834–2839, doi:10.3762/bjoc.20.239

• Paris, France 10.3762/bjoc.20.239 Abstract The use of alkylzinc bromides in the multicomponent Mannich reaction is described. Heteroleptic organozinc compounds were obtained in THF or 2-MeTHF by direct insertion of zinc dust into the C–Br bond of alkyl bromides. It was found that the presence of a

• primary organozinc reagents. Keywords: alkyl bromides; branched amines; Mannich reaction; multicomponent reaction; zinc; Introduction The multicomponent Mannich reaction is one of the most powerful tools available in organic synthesis for the straightforward generation of α-branched amines [1][2][3

• ]. Since its discovery in 1912, the reaction has benefitted from regular improvements over the years and recent developments, such as the use of organometallic species as nucleophiles in the so-called “organometallic Mannich reaction”, which have helped to expand the boundaries of the original process [4

Synthesis and antimycotic activity of new derivatives of imidazo[1,2-a]pyrimidines

• Dmitriy Yu. Vandyshev,
• Daria A. Mangusheva,
• Khidmet S. Shikhaliev,
• Kirill A. Scherbakov,
• Oleg N. Burov,
• Alexander D. Zagrebaev,
• Tatiana N. Khmelevskaya,
• Alexey S. Trenin and
• Fedor I. Zubkov

Beilstein J. Org. Chem. 2024, 20, 2806–2817, doi:10.3762/bjoc.20.236

• , it is worth mentioning the work of Li and co-workers (2011) [20], who described a single example of the formation of such structures by carrying out an organocatalytic domino aza-Michael–Mannich reaction between benzylidene-1H-imidazol-2-amine and cinnamaldehyde. Although the imidazo[1,2-a

Evaluating the halogen bonding strength of a iodoloisoxazolium(III) salt

• Dominik L. Reinhard,
• Anna Schmidt,
• Marc Sons,
• Julian Wolf,
• Elric Engelage and
• Stefan M. Huber

Beilstein J. Org. Chem. 2024, 20, 2401–2407, doi:10.3762/bjoc.20.204

• in a Mannich reaction [4]. In 2018, our group showed in a proof-of-principle study [5] that the Lewis acid catalysis by DAI salts is based on halogen bonding (XB), an interaction between a Lewis base (XB acceptor) and an electrophilic halogen atom in the Lewis acid (XB donor) [6][7][8][9][10]. In

Multicomponent syntheses of pyrazoles via (3 + 2)-cyclocondensation and (3 + 2)-cycloaddition key steps

• Ignaz Betcke,
• Alissa C. Götzinger,
• Maryna M. Kornet and
• Thomas J. J. Müller

Beilstein J. Org. Chem. 2024, 20, 2024–2077, doi:10.3762/bjoc.20.178

• pyrazole-4-carboxylates. Shen et al. used Yb(PFO)3 (PFO: perfluorooctanoate), a mild and highly efficient catalyst shown to be effective in the Mannich reaction [94], to synthesize these pyrazoles 65 (Scheme 21) [95]. The Lewis acid catalyst activates and stabilizes the enol tautomer of β-ketoesters

Cofactor-independent C–C bond cleavage reactions catalyzed by the AlpJ family of oxygenases in atypical angucycline biosynthesis

• Jinmin Gao,
• Liyuan Li,
• Shijie Shen,
• Guomin Ai,
• Bin Wang,
• Fang Guo,
• Tongjian Yang,
• Hui Han,
• Zhengren Xu,
• Guohui Pan and
• Keqiang Fan

Beilstein J. Org. Chem. 2024, 20, 1198–1206, doi:10.3762/bjoc.20.102

• and 3 through a rare Mannich reaction. This results in the formation of prekinamycin harboring a diazo group [14]. Given the presence of AlpJ-like oxygenases and ʟ-glutamylhydrazine biosynthetic enzymes in the gene clusters of lomaiviticin, nenestatin, and fluostatins [16][17][18][19][20], it is

Bismuth(III) triflate: an economical and environmentally friendly catalyst for the Nazarov reaction

• Manoel T. Rodrigues Jr.,
• Aline S. B. de Oliveira,
• Ralph C. Gomes,
• Amanda Soares Hirata,
• Lucas A. Zeoly,
• Hugo Santos,
• João Arantes,
• Catarina Sofia Mateus Reis-Silva,
• João Agostinho Machado-Neto,
• Leticia Veras Costa-Lotufo and
• Fernando Coelho

Beilstein J. Org. Chem. 2024, 20, 1167–1178, doi:10.3762/bjoc.20.99

• synthesis has been reported for several transformations, such as epoxide opening [56], ketal formation and deprotection [57][58], Mannich reaction [59], intramolecular Sakurai cyclization [60], alcohol oxidation [61], aromatic hydrocarbon nitration [62], imine allylation [63], Knoevenagel condensation [64

Selective construction of dispiro[indoline-3,2'-quinoline-3',3''-indoline] and dispiro[indoline-3,2'-pyrrole-3',3''-indoline] via three-component reaction

• Ziying Xiao,
• Fengshun Xu,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2023, 19, 1234–1242, doi:10.3762/bjoc.19.91

• spirooxindoles, in which the in situ-generated Michael adduct of 3-ethoxycarbonylmethyleneoxindole underwent a Mannich reaction and annulation reaction with in situ-generated aldimines (reaction 1 in Scheme 1) [50][51]. Tanaka reported chiral quinidine derivative-catalyzed Michael–Henry cascade reactions of

Palladium-catalyzed enantioselective three-component synthesis of α-arylglycine derivatives from glyoxylic acid, sulfonamides and aryltrifluoroborates

• Bastian Jakob,
• Nico Schneider,
• Luca Gengenbach and
• Georg Manolikakes

Beilstein J. Org. Chem. 2023, 19, 719–726, doi:10.3762/bjoc.19.52

• imine species provide a very flexible approach to the arylglycine scaffold [2][9]. The Petasis borono-Mannich reaction constitutes a prominent example for such an imine-based multicomponent reaction (Scheme 1a). The reaction of glyoxylic acid, an amine component and an arylboronic acid offers a highly

• modular access to arylglycines from three readily available building blocks [10][11][12]. The Petasis borono-Mannich reaction usually proceeds in the absence of any external catalyst via zwitterionic intermediates and an intramolecular transfer of the aryl residue form the activated boronate to the

• palladium-catalyzed three-component reactions between arylboronic or carboxylic acids, amides or sulfonamides and different aldehyde components as attractive and broadly applicable alternative to the classical Petasis borono-Mannich reaction (Scheme 1b) [17][18][19][20][21]. Recently, we were able to extend

Enolates ambushed – asymmetric tandem conjugate addition and subsequent enolate trapping with conventional and less traditional electrophiles

• Péter Kisszékelyi and
• Radovan Šebesta

Beilstein J. Org. Chem. 2023, 19, 593–634, doi:10.3762/bjoc.19.44

• using acyclic enones 14 [27]. Their tandem conjugate addition/Mannich reaction methodology offers access to various non-cyclic β-aminoketones 16 with multiple contiguous stereocenters in high diastereo- and enantioselectivity (Scheme 5a). Additionally, chiral isoindolinones 18 and 2,3,4-trisubstituted

Identification and determination of the absolute configuration of amorph-4-en-10β-ol, a cadinol-type sesquiterpene from the scent glands of the African reed frog Hyperolius cinnamomeoventris

• Angelique Ladwig,
• Markus Kroll and
• Stefan Schulz

Beilstein J. Org. Chem. 2023, 19, 167–175, doi:10.3762/bjoc.19.16

• using diethyl (2-methylallyl)phosphonate gave diene ketone S-18 [13]. Here, we envisioned that a Mannich reaction would introduce the required α,β-unsaturated carbonyl system needed for the following intramolecular Diels–Alder reaction, that likely would proceed directly under these conditions. This

• concept proved to be difficult to achieve, but by optimization of different parameters of this Domino reaction, the required enantiomerically almost pure ketones 9–11 were obtained (Table 1). The Mannich reaction worked best using diisopropylammonium trifluoroacetate as the catalyst [22]. The isolation of

Vicinal ketoesters – key intermediates in the total synthesis of natural products

• Marc Paul Beller and
• Ulrich Koert

Beilstein J. Org. Chem. 2022, 18, 1236–1248, doi:10.3762/bjoc.18.129

• for different purposes in the syntheses of a range of oxindole alkaloids. The start of the synthesis of (rac)-corynoxine (76) was the conversion of tryptamine (70) to oxindole 71, which was used in a chemoselective Mannich reaction with aldehyde 72, introducing the α-ketoester moiety (Scheme 12) [27

• -substitution. Subsequent transesterification gave the α-ketoester 75, which was used in a Wittig reaction. The undesired Z-configured double bond was isomerized to the E-alkene and final hydrogenation delivered corynoxine (76). (+)-Gracilamine The Mannich reaction was also used by Nagasawa et al. as a key step

• in the synthesis of (+)-gracilamine (83), a pentacyclic alkaloid isolated from the plant Galanthus gracilis, (Scheme 13) [28]. The synthesis started from readily available sesamol (79) and imine 78 which gave the advanced intermediate 80 in ten steps. An intramolecular Mannich reaction of compound 80

Inductive heating and flow chemistry – a perfect synergy of emerging enabling technologies

• Conrad Kuhwald,
• Sibel Türkhan and
• Andreas Kirschning

Beilstein J. Org. Chem. 2022, 18, 688–706, doi:10.3762/bjoc.18.70

• materials to inductively heat up glass reactors. For the Biginelli reaction solubility of the starting urea (22) as well as the products 24a and 24b were an issue being overcome by using a solvent mixture of PEG/DMF 1:1. Also the proline-catalyzed asymmetric Mannich reaction was achieved with cyclohexanone

Cholyl 1,3,4-oxadiazole hybrid compounds: design, synthesis and antimicrobial assessment

• Anas J. Rasras,
• Mohamed El-Naggar,
• Nesreen A. Safwat and
• Raed A. Al-Qawasmeh

Beilstein J. Org. Chem. 2022, 18, 631–638, doi:10.3762/bjoc.18.63

• exhibited selective activity against fungi only. Keywords: antibacterial; cholic acid; heterocyclic; Mannich reaction; oxadiazole; Introduction Microbial infections caused by Gram-negative and Gram-positive bacteria embarrass the health care system worldwide [1]. Pathogens such as Escherichia coli

• ]. Having oxadiazole-2-thiol 2 at hands, the reactive thiol was subjected to the reaction with propargyl bromide and sodium carbonate as a base to afford the thiopropargylated derivative 3 in 82% yield after 24 h (Scheme 2) [33]. Compound 3 was the starting point for a Mannich reaction to generate a library

Synthesis of O⁶-alkylated preQ₁ derivatives

• Laurin Flemmich,
• Sarah Moreno and
• Ronald Micura

Beilstein J. Org. Chem. 2021, 17, 2295–2301, doi:10.3762/bjoc.17.147

• natural sources. Earlier syntheses of preQ1, preQ0 and m6preQ0 The synthesis of preQ1 has been first described by Goto starting from 2-methylthio-6-methoxy-7-methyl-7-deazapurine and requiring more than ten steps [21]. More efficient was a procedure reported by Nishimura applying a Mannich reaction with

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

• hydroxylated malonate 53 catalyzed by NHC 55. Oxidative [4 + 2] cycloaddition of enals 57 to coumarins 56 catalyzed by NHC 59. Asymmetric [3 + 2] cycloaddition of coumarins 43 to azomethine ylides 60 organocatalyzed by quinidine 62. Synthesis of α-benzylaminocoumarins 64 through Mannich reaction between 4

• presence of a carbonyl group in the coumarin, since it makes a hydrogen bond with the organocatalyst and when it is replaced by other electron-withdrawing groups, the hydrogen bond formation is blocked, consequently there is no product formation (Scheme 19). Lin et al. described an organocatalyzed Mannich

• reaction between 4-hydroxycoumarins 1 and aromatic imines 63 for the synthesis of α-benzylaminocoumarins 64 [54]. Among the cinchona alkaloid derivatives evaluated in this reaction, cupreine (65) was found to be the best option in terms of yields and enantioselectivities (Scheme 20). Both electron

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

• number of classical methodologies have been used for their synthesis, in which the key step is the generation of the six-membered ring, including the aldol reaction, the reductive amination, Mannich reaction, ring closing metathesis, Diels–Alder reaction with imines as dienophiles, aza-Prins cyclization

CF₃-substituted carbocations: underexploited intermediates with great potential in modern synthetic chemistry

• Anthony J. Fernandes,
• Armen Panossian,
• Bastien Michelet,
• Agnès Martin-Mingot,
• Frédéric R. Leroux and
• Sébastien Thibaudeau

Beilstein J. Org. Chem. 2021, 17, 343–378, doi:10.3762/bjoc.17.32

Direct synthesis of anomeric tetrazolyl iminosugars from sugar-derived lactams

• Michał M. Więcław and
• Bartłomiej Furman

Beilstein J. Org. Chem. 2021, 17, 115–123, doi:10.3762/bjoc.17.12

• as the aldol reaction [30], Michael addition [31], Mannich reaction [32], and hydrogenation [33]. Results and Discussion Quite recently Xie and Dixon showed that it is possible to synthesize α-tetrazolylamines from simple and linear tertiary amides using an iridium-based catalytic protocol [19]. They

• widely used as organocatalysts. Such moieties are employed in a number of important synthetic transformations, including the aldol reaction [30], Michael addition [31], Mannich reaction [32], and hydrogenation [33]. We plan to test these possibilities in the near future. Stereochemistry and configuration

Recent progress in the synthesis of homotropane alkaloids adaline, euphococcinine and N-methyleuphococcinine

• Dimas J. P. Lima,
• Antonio E. G. Santana,
• Michael A. Birkett and
• Ricardo S. Porto

Beilstein J. Org. Chem. 2021, 17, 28–41, doi:10.3762/bjoc.17.4

• forms. Key (homotropane construction) steps included: i) inter and intramolecular Mannich reaction; ii) double Michael addition in the cyclooctadienone derivative; and iii) intramolecular 1,3-dipolar cycloaddition. As shown in Scheme 1, the azabicyclononane ring is an interesting target for strategies

• based on the Mannich reaction. This methodology is mostly used in some cases, with few steps, and from commercially available reagents. Holmes synthesis – 1995 Davison and Holmes prepared racemic (±)-adaline (1) and (±)-euphococcinine (2). The key step in the synthesis involved the intramolecular

• on an intramolecular Mannich reaction that occurred in intermediate 31 (Scheme 4). Thus, thiolactam 26 was quantitatively converted to lactam 27, using the Belleau's reagent [43]. 27 was treated with Weinreb amide 33, prepared from commercially available bromoacetyl bromide [44] to provide the

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

• , 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

Asymmetric Mannich reactions of (S)-N-tert-butylsulfinyl-3,3,3-trifluoroacetaldimines with yne nucleophiles

• Ziyi Li,
• Li Wang,
• Yunqi Huang,
• Haibo Mei,
• Hiroyuki Konno,
• Hiroki Moriwaki,
• Vadim A. Soloshonok and
• Jianlin Han

Beilstein J. Org. Chem. 2020, 16, 2671–2678, doi:10.3762/bjoc.16.217

• afford diastereomerically pure compounds. The purified Mannich addition products were deprotected to give the target enantiomerically pure trifluoromethylpropargylamines. A mechanistic rationale for the observed stereochemical outcome is discussed. Keywords: arylethynes; asymmetric Mannich reaction; C

• compounds for the synthesis of biologically relevant targets and their self-disproportionation of enantiomers (SDE) properties [58][59][60] are currently under study and will be reported in due course. Experimental General procedure for the Mannich reaction of arylethynes with sulfinylimine: Into an oven