Formaldehyde surrogates in multicomponent reactions

• Cecilia I. Attorresi,
• Javier A. Ramírez and
• Bernhard Westermann

Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45

• this context, quinoline and its derivatives are privileged structures in several natural products and biologically active compounds, rendering this scaffold an important synthetic target. An attractive strategy to afford tetrahydroquinolines and quinolines is the Povarov reaction, a type of aza-Diels

• –Alder reaction between an imine and an alkene (Scheme 6). Very successfully, the multicomponent version of the Povarov reaction using aldehydes, anilines, and alkenes has been explored in a three-component cascade reaction to quinolines [28][29][30][31] (Scheme 6). Furthermore, protocols have been

• developed in which the alkene compound has been replaced with other surrogates for electrophilic addition, such as ketones [32][33][34]. In the case of the carbonyl component, it is generally an aromatic aldehyde [30][33][34] and there are not many reports on using formaldehyde in the Povarov reaction. In a

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

• diastereomeric ratios in a couple of cases. On a 1 mmol scale with reduced catalyst loading the reaction proceeded in a similar fashion with good yield and enantioselectivity (70%, 89% ee). The Povarov reaction of imines 87a–h and alkenylindoles 88a–i catalyzed by CPA (R)-C23 was utilized to give asymmetric

• be carried out in a one-pot fashion with comparable results and without significant variation from the two-step procedure. Utilization of the Povarov reaction and subsequent oxidation by DDQ was also done by Wang et al. in 2020 [54]. In situ-formed imines from anilines 91 and benzaldehydes 92 were

The unique reactivity of 5,6-unsubstituted 1,4-dihydropyridine in the Huisgen 1,4-diploar cycloaddition and formal [2 + 2] cycloaddition

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

Beilstein J. Org. Chem. 2023, 19, 982–990, doi:10.3762/bjoc.19.73

• ; isoquinolino[1,2-f][1,6]naphthyridine; Introduction Among various well-known cycloaddition reactions such as the 1,3-dipolar cycloaddition reaction, Diels–Alder reaction, and the Povarov reaction, the cycloaddition reaction of Huisgen 1,4-dipoles with activated alkenes received increasing attention [1][2][3

• -fused tetrahydroquinolines (reaction 1 in Scheme 1) [41][42]. Menéndez and co-workers reported a Yb(OTf)3-mediated Povarov reaction of imines and N-alkyl-1,4-dihydropyridines for the synthesis of hexahydrobenzo[h][1,6]naphthyridines (reaction 2 in Scheme 1) [43]. Khan and co-workers employed a one-pot

• Povarov reaction of 3-aminocoumarins, aldehydes, and 5,6-unsubstituted 1,4-dihydropyridine derivatives for the construction of exo-hexahydrochromeno[3,4-h][1,6]naphthyridine-3-carboxylate derivatives (reaction 3 in Scheme 1) [44]. In these reactions, the 5,6-unsubstituted 1,4-dihydropyridines usually

Microwave-assisted multicomponent reactions in heterocyclic chemistry and mechanistic aspects

• Shivani Gulati,
• Stephy Elza John and
• Nagula Shankaraiah

Beilstein J. Org. Chem. 2021, 17, 819–865, doi:10.3762/bjoc.17.71

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• tautomer 147, and the CPA-catalysed Povarov reaction between them gives the enantioenriched THQ 144 in good yields and enantioselectivities (4 examples, up to 97:3 er). This reactivity has been extended to enamides 148, with the imine generated from the α-amino acid 149 now reacting with 148 in a CPA

• -catalysed Povarov reaction rather than with its own tautomer (Scheme 21a) [70]. Zhang and You developed a catalytic dearomatisation reaction of indoles 150 using similar chemistry, where the generated imine 151 now reacts intramolecularly with a pendant nucleophile and is further oxidised to a carbocation

Selectivity in multiple multicomponent reactions: types and synthetic applications

• Ouldouz Ghashghaei,
• Francesca Seghetti and
• Rodolfo Lavilla

Beilstein J. Org. Chem. 2019, 15, 521–534, doi:10.3762/bjoc.15.46

• the Union Concept. A) Petasis-Ugi combination; B) GBB-Ugi/Passerini combination; C) Reissert MCRs linked to a Povarov reaction. Selective MMCRs featuring FGs with distinct reactivity along the sequence. A) Synthesis of aminomethyltetrazoles by consecutive isocyanide MCRs. B) Interrupted Ugi/Joullié

Aza-Diels–Alder reaction between N-aryl-1-oxo-1H-isoindolium ions and tert-enamides: Steric effects on reaction outcome

• Amitabh Jha,
• Ting-Yi Chou,
• Zainab ALJaroudi,
• Bobby D. Ellis and
• T. Stanley Cameron

Beilstein J. Org. Chem. 2014, 10, 848–857, doi:10.3762/bjoc.10.81

• major highlight of this work. Results and Discussion Our literature search revealed that although tert-enamides have been used as dienophiles for the Povarov reaction to build 1,2,3,4-tetrahydroquinoline blocks [25][26][37], there were no reports of their usage in the inverse electron demand hetero

Facile synthesis of functionalized tetrahydroquinolines via domino Povarov reactions of arylamines, methyl propiolate and aromatic aldehydes

• Jing Sun,
• Hong Gao,
• Qun Wu and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2012, 8, 1839–1843, doi:10.3762/bjoc.8.211

• proceeded smoothly to give polysubstituted 1,2,3,4-tetrahydroquinolines in moderate yields. The reaction is believed to involve the Povarov reaction of in situ generated β-enamino ester with the in situ formed aromatic imine. Keywords: β-enamino ester; domino reaction; electron-deficient alkyne; Povarov

• developed as the most powerful synthetic routes to construct oxygen or nitrogen-containing six-membered heterocycles [4][5][6][7][8]. In recent years, the imine Diels–Alder reaction (also known as Povarov reaction) and the [4 + 2] cycloaddition reaction of imines (obtained from the corresponding aromatic

• ]. However, a survey of literature reveals that a Povarov reaction with in situ generated β-enamino ester as dienophile has not been reported until now. Recently, Zhu and Masson successfully developed three-component Povarov reactions using enamides as dienophiles leading to a highly efficient synthesis of