Copper-catalyzed multicomponent reactions for the efficient synthesis of diverse spirotetrahydrocarbazoles

• Shao-Cong Zhan,
• Ren-Jie Fang,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2022, 18, 796–808, doi:10.3762/bjoc.18.80

• [carbazole-2,3'-indolines], spiro[carbazole-3,5'-pyrimidines] and spiro[carbazole-3,1'-cycloalkanes] in satisfactory yields and with high diastereoselectivity. Keywords: Diels–Alder reaction; indole; indolo-2,3-quinodimethane; Levy reaction; tetrahydrocarbazole; spirooxindole; Introduction

• Tetrahydrocarbazole is one of the most privileged heterocyclic core structures. It widely exists in various naturally occurring alkaloids and pharmacologically active compounds exhibiting important bioactivities such as antitumor activity and antiprotein kinase C activity [1][2][3]. Additionally, the corresponding

• ]. Therefore, many [4 + 2] reactions of 3-vinylindolines or 2-vinylindolines with diverse dienophiles have been successfully developed for the synthesis of many tetrahydrocarbazole and carbazole derivatives [22][23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47

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

• acid. Secondly, the Diels–Alder reaction of indole-chalcone A with the dienophile results in the tetrahydrocarbazole B having an exocyclic C=C bond. Thirdly, a new tetrahydrocarbazole intermediate C is formed by a 1,3-H shifting process. The resulting tetrahydrocarbazole intermediate (C) might be a

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

Protein–protein interactions in bacteria: a promising and challenging avenue towards the discovery of new antibiotics

• Laura Carro

Beilstein J. Org. Chem. 2018, 14, 2881–2896, doi:10.3762/bjoc.14.267

• (FP) assay of the selected candidates, the substituted tetrahydrocarbazole 11 (Figure 3) was found to not only completely occupy E. coli SC subsite I with the highest affinity (IC50 = 115 μM) and to inhibit in vitro DNA replication, but also to have antibacterial activity against several Gram-positive

• and Gram-negative pathogens, namely Bacillus subtilis, Staphylococcus aureus, Escherichia coli and Acinetobacter baylyi with MICs ranging from 39 to 78 μM [62]. A year later, further SAR investigations from the same research group led to the identification of another tetrahydrocarbazole derivative 12

The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• of activation. This method provided a route to access the enantiomerically enriched tetrahydrocarbazole scaffold-containing compounds 14 (Scheme 6 and Scheme 7) [29]. One of these valuable products is a synthetic precursor of the pharmacologically active compound 15, used to treat Alzheimer and other

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

• Rajeev S. Menon,
• Akkattu T. Biju and
• Vijay Nair

Beilstein J. Org. Chem. 2016, 12, 444–461, doi:10.3762/bjoc.12.47

• 72 with the NHC precatalyst 73 alone, on the other hand, afforded isochromeno(4,3-c)isochromene derivatives 75 (Scheme 44) [61]. A one-pot multicatalytic reaction for the asymmetric synthesis of complex tetracyclic tetrahydrocarbazole derivatives from readily available precursors was described by

• Melchiorre. A Diels–Alder reaction of indole-2,3-quinodimethane 76 (generated from 77 and the prolinol catalyst 78 ) with the enone 79 affords a tetrahydrocarbazole derivative 80. The NHC precatalyst 22 then promotes an intramolecular cross-benzoin condensation of the keto-aldehyde to furnish the tetracyclic

• –Michael cascade. Divergent catalytic dimerization of 2-formylcinnamates. One-pot, multicatalytic asymmetric synthesis of tetrahydrocarbazole derivatives. NHC-chiral secondary amine co-catalysis for the synthesis of complex spirocyclic scaffolds.

Synthesis of constrained analogues of tryptophan

• Elisabetta Rossi,
• Valentina Pirovano,
• Marco Negrato,
• Giorgio Abbiati and
• Monica Dell’Acqua

Beilstein J. Org. Chem. 2015, 11, 1997–2006, doi:10.3762/bjoc.11.216

• -catalysed diastereoselective [4 + 2] cycloaddition of vinylindoles and methyl 2-acetamidoacrylate, leading to methyl 3-acetamido-1,2,3,4-tetrahydrocarbazole-3-carboxylate derivatives, is described. Treatment of the obtained cycloadducts under hydrolytic conditions results in the preparation of a small

• -carbon atom of the amino acid function and the C-2 carbon of the indole ring (tetrahydrocarbazole derivatives). The first report on the synthesis and biological evaluation of a constrained tryptophan analogue appeared in the literature in 1973 [11]. Maki and co-workers reported the synthesis of 3-amino

• -1,2,3,4-tetrahydrocarbazole-3-carboxylic acid as a rigid analogue of α-methyltryptophan, a well known unnatural amino acid able to inhibit α-chymotrypsin activity, Figure 2 (A). Hardening tryptophan in β-carboline or carbazole frameworks has been used by Hénichart and co-workers in their studies devoted

Synthesis of indole-based propellane derivatives via Weiss–Cook condensation, Fischer indole cyclization, and ring-closing metathesis as key steps

• Sambasivarao Kotha,
• Ajay Kumar Chinnam and
• Arti Tiwari

Beilstein J. Org. Chem. 2013, 9, 2709–2714, doi:10.3762/bjoc.9.307

• vincristine-resistant KB cancer cells [23][24]. Minfiensine alkaloid [25][26][27][28][29][30][31] containing a novel 1,2,3,4-tetrahydrocarbazole ring skeleton shows anticancer activity [32]. König and co-workers identified some propellane derivatives as cannabinoid CB1 receptor antagonists [33], which are

One-step synthesis of pyridines and dihydropyridines in a continuous flow microwave reactor

• Mark C. Bagley,
• Vincenzo Fusillo,
• Robert L. Jenkins,
• M. Caterina Lubinu and
• Christopher Mason

Beilstein J. Org. Chem. 2013, 9, 1957–1968, doi:10.3762/bjoc.9.232

• synthetic transformations (Scheme 1), including Bohlmann–Rahtz cyclodehydration of aminodienones 1 to the corresponding pyridines 2 [44][45], Fischer indole synthesis of tetrahydrocarbazole 5 from phenylhydrazine (3) and cyclohexanone (4) [44], and hydrolysis of 4-chloromethylthiazole (6) to give the

Palladium-catalyzed dual C–H or N–H functionalization of unfunctionalized indole derivatives with alkenes and arenes

• Gianluigi Broggini,
• Egle M. Beccalli,
• Andrea Fasana and
• Silvia Gazzola

Beilstein J. Org. Chem. 2012, 8, 1730–1746, doi:10.3762/bjoc.8.198

• . The subsequent transfer of carbon monoxide with stereochemical retention determines the generation of the σ-acyl-palladium complex XVIII, which in turn is converted in the final cis-substituted tetrahydrocarbazole by methanolysis giving the carboxylation step. Again, the released Pd(0) species

An overview of the key routes to the best selling 5-membered ring heterocyclic pharmaceuticals

• Marcus Baumann,
• Ian R. Baxendale,
• Steven V. Ley and
• Nikzad Nikbin

Beilstein J. Org. Chem. 2011, 7, 442–495, doi:10.3762/bjoc.7.57

• have also been reported, however, these usually rely on longer reaction sequences and require more expensive starting materials (Scheme 30) [42][43]. Etodolac (153, Lodine) is a racemic non-steroidal anti-inflammatory tetrahydrocarbazole derivative used to treat inflammation and prescribed for general