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

• -unsaturated imines and variety of structures. The hetero-Diels–Alder and inverse electron demand hetero-Diels–Alder reactions. Different strategies to promote the activation of dienes and dienophiles in IEDADA reactions. Examples of non-covalent interactions in organocatalysis. Structure of a cinchona

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

• the residence times of the reactions outperformed those of the analogous experiments carried out under batch conditions by far [62][63][64]. The heating method was also successfully tested on various thermally conducted pericyclic reactions (Scheme 10, case A), such as in (hetero)-Diels–Alder

• reactions (anthracene (33) and maleic anhydride (34) to the cycloaddition adduct 35 and chromene carbaldehyde 36 and enol ether 37 to the diastereomeric pyrano-chromenes 38), Alder-En reactions (oxomalonate diethyl ester (39) and β-pinene (40) to give the α-pinene derivative 41), and the thermal

First thia-Diels–Alder reactions of thiochalcones with 1,4-quinones

• Grzegorz Mlostoń,
• Katarzyna Urbaniak,
• Paweł Urbaniak,
• Anna Marko,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2018, 14, 1834–1839, doi:10.3762/bjoc.14.156

• cycloadduct was isolated in 37% yield. Keywords: hetero-Diels–Alder reactions; quinone dyes; quinones; sulfur heterocycles; thiochalcones; Introduction Hetero-Diels–Alder reactions are considered to be a powerful methodology widely explored for the synthesis of six-membered heterocycles [1][2] with numerous

• applications for the construction of complex molecules including naturally occurring products [3][4], drugs [5][6], agrochemicals [7], etc. In addition, asymmetric hetero-Diels–Alder reactions are of current interest [8][9][10]. Whereas aza- and oxa-Diels–Alder reactions are frequently applied, thia-Diels

Stereo- and regioselectivity of the hetero-Diels–Alder reaction of nitroso derivatives with conjugated dienes

• Lucie Brulíková,
• Aidan Harrison,
• Marvin J. Miller and
• Jan Hlaváč

Beilstein J. Org. Chem. 2016, 12, 1949–1980, doi:10.3762/bjoc.12.184

• biologically active compounds. It is a variant of the Diels–Alder reaction where either the diene or the dienophile contains a heteroatom. Hetero-Diels–Alder reactions between conjugated dienes and nitroso dienophiles affording 1,2-oxazines are utilized for the synthesis of many biologically active molecules

• acylnitroso dienophile 5 was generated in the presence of thebaine (4) to selectively give the 1,2-oxazine 6 (Scheme 2). Several excellent reviews on nitroso hetero-Diels–Alder reactions have been published in the past, including general reviews on hetero-Diels–Alder reactions and their applications in

• organic synthesis [15][16][17][18][19][20][21][22][23][24], applications of nitroso hetero-Diels–Alder reactions for the synthesis of azasugars [10], and the utilization of nitroso hetero-Diels–Alder reactions in natural product synthesis [9][25] and the synthesis of bioactive molecules [26]. However

Hetero-Diels–Alder reactions of hetaryl and aryl thioketones with acetylenic dienophiles

• Grzegorz Mlostoń,
• Paulina Grzelak,
• Maciej Mikina,
• Anthony Linden and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2015, 11, 576–582, doi:10.3762/bjoc.11.63

• sulfones. Keywords: dimethyl acetylenedicarboxylate (DMAD); hetero-Diels–Alder reactions; high pressure reactions; methyl propiolate; thioketones; thiopyrans; Introduction A series of recent publications evidence that, in contrast to earlier opinions, thioketones are useful building blocks for the

• of the products were determined based on the spectroscopic data. Thus, similar to hetero-Diels–Alder reactions with maleic anhydride [14], the C=C bond of the thiophene ring of 1h is part of the reactive heterodiene system. The reactions of 2b with thiobenzosuberone 1b and thiobenzosuberenone 1c were

• polyheterocycles [22][23][24]. It is worth of mentioning, that the described hetero-Diels–Alder reactions with aromatic thioketones as heterodienes, display certain similarities to the reported organometallic pathways observed in their reactions with triiron dodecacarbonyl Fe3(CO)12 [25][26]. Experimental General

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

• the dienophile, at least two regioisomers can be visualized for these compounds. Based on our characterization results, only one regioisomer, where the substitution was at position 5 of the isoindoloquinoline ring, was exclusively formed in these reactions. Inverse-electron demand hetero-Diels–Alder

• reactions are known to exhibit this type of regioselectivity, and it can be explained based on charge control [40] (Scheme 2). The polarization of the iminium cation places the positive charge on the benzylic C of the isoindole ring and subsequently the N-aryl ring develops a negative charge at the ortho

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

• -type reactions, hetero Diels–Alder reactions, 1,3-dipolar cycloadditions and nitroso aldol reactions [93]. The process was firstly accomplished with preformed aryl-substituted aldimines [94] and then developed as a MCR for less stable alkyl-substituted aldimines, which were prepared in situ from

Stereodivergent synthesis of jaspine B and its isomers using a carbohydrate-derived alkoxyallene as C₃-building block

• Volker M. Schmiedel,
• Stefano Stefani and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2013, 9, 2564–2569, doi:10.3762/bjoc.9.291

• auxiliaries for the synthesis of enantiopure natural products such as preussin [39] and anisomycin [40] or in hetero Diels–Alder reactions [41][42]. For the stereodivergent synthesis of both enantiomers of jaspine B (1), we chose diacetoneglucose-derived alkoxyallene 11, which is easily accessible on gram

A versatile and efficient approach for the synthesis of chiral 1,3-nitroamines and 1,3-diamines via conjugate addition to new (S,E)-γ-aminated nitroalkenes derived from L-α-amino acids

• Vera Lúcia Patrocinio Pereira,
• André Luiz da Silva Moura,
• Daniel Pais Pires Vieira,
• Leandro Lara de Carvalho,
• Eliz Regina Bueno Torres and
• Jeronimo da Silva Costa

Beilstein J. Org. Chem. 2013, 9, 832–837, doi:10.3762/bjoc.9.95

• hetero-Diels–Alder reactions [27][28][29][30][31] and even participate in cross-coupling reactions [32]. Due to this notable reactivity, obtaining new chiral and achiral nitroalkenes is of great importance in synthetic organic chemistry. Achiral nitroalkenes, specifically the chemically stable β-trans

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

• reaction; tetrahydroquinoline; Introduction The Diels–Alder reaction is recognized as a powerful reaction in synthetic strategies for the production of natural and unnatural polycarbocycles and polyheterocycles [1][2][3]. Therefore, the hetero-Diels–Alder reactions and domino reaction procedures have been

Addition of lithiated enol ethers to nitrones and subsequent Lewis acid induced cyclizations to enantiopure 3,6-dihydro-2H-pyrans – an approach to carbohydrate mimetics

• Fabian Pfrengle and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2010, 6, No. 75, doi:10.3762/bjoc.6.75

• efficient preparation include Prins cyclizations, intramolecular substitutions, ring closure metathesis, and hetero Diels–Alder reactions [1][2]. Our group recently reported the synthesis of enantiopure aminopyrans employing as the key step a Lewis acid induced rearrangement of 1,2-oxazines to bicyclic

Synthesis of some novel annulated pyrido[2,3-d]pyrimidines via stereoselective intramolecular hetero Diels–Alder reactions of 1-oxa-1,3-butadienes

• Mohit L. Deb and
• Pulak J. Bhuyan

Beilstein J. Org. Chem. 2010, 6, No. 11, doi:10.3762/bjoc.6.11

• preparation of these complex molecules. However, there still remains many challenges in the synthesis of these naturally occurring complex molecules [22][23][24][25][26][27][28][29][30][31]. Hetero Diels–Alder reactions [32][33][34][35] are becoming a mainstay of heterocyclic and natural product synthesis

• complex annulated pyrido[2,3-d]pyrimidines by intramolecular hetero Diels–Alder reactions involving 1-oxa-1,3-butadienes (Scheme 1). The key intermediate, the 2-chloro-3-formyl uracil derivative 1 (β-halo aldehyde), was prepared by the reaction of N,N-dimethyl barbituric acid with Vielsmeier reagent (DMF

• , 15.82. Stereoselective synthesis of some new complex annulated pyrido[2,3-d]pyrimidines by intramolecular hetero Diels–Alder reactions involving 1-oxa-1,3-butadienes. Synthesis of some novel annulated pyrido[2,3-d]pyrimidines 6/7.a Supporting Information Supporting Information File 30: Spectroscopic