N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity

• Peter Langer

Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240

• Peter Langer Institut für Chemie, Universität Rostock, Albert-Einstein-Str. 3a, 18059 Rostock, Germany 10.3762/bjoc.20.240 Abstract Indigo, indirubin, and isoindigo derivatives have been used for centuries as pigments. Since the 1990s, a new aspect of the chemistry of this type of compounds is

• their activity against various types of cancer. N-Glycosides of indigo, indirubin, and isoindigo, blue, red, and yellow sugars, turned out to be of special interest because of their high cancerostatic activity and structural novelty. The present article provides an account on the synthesis and

• anticancer activity of these compounds. Keywords: cancerostatic activity; carbohydrates; heterocycles; N-glycosides; indirubin; Introduction Indigo (1a), known for more than 6000 years and originally produced from indigo plants in India, represents a famous traditional blue pigment which was an expensive

Supramolecular assemblies of amphiphilic donor–acceptor Stenhouse adducts as macroscopic soft scaffolds

• Ka-Lung Hung,
• Leong-Hung Cheung,
• Yikun Ren,
• Ming-Hin Chau,
• Yan-Yi Lam,
• Takashi Kajitani and
• Franco King-Chi Leung

Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142

• , stiff-stilbene [26], azobenzene [27][28], molecular motors [19][29][30], spiropyran [31][32][33], indigo [34][35], and donor–acceptor Stenhouse adducts (DASAs) [36][37], have been used in supramolecular systems for photoswitchable smart electronic, optoelectronic, and biomedical materials [30][38][39

• are available. UV-light-driven supramolecular transformations on a macroscopic length scale were pioneered by Leung and Feringa [42][43]. Besides, we recently reported the first indigo amphiphiles in fabrication of macroscopic soft scaffolds with photoshrinking properties as a smart functional cell

Carbonylative synthesis and functionalization of indoles

• Alex De Salvo,
• Raffaella Mancuso and
• Xiao-Feng Wu

Beilstein J. Org. Chem. 2024, 20, 973–1000, doi:10.3762/bjoc.20.87

• ring. It was discovered in 1866 by Baeyer and Knop as the basic structure of the natural dye indigo, from which it is derived [1]. The indole ring is a common structural element found in both natural and synthetic products, including pharmaceuticals, agrochemicals, dyes, herbicides, and materials [2][3

Switchable molecular tweezers: design and applications

• Pablo Msellem,
• Maksym Dekthiarenko,
• Nihal Hadj Seyd and
• Guillaume Vives

Beilstein J. Org. Chem. 2024, 20, 504–539, doi:10.3762/bjoc.20.45

Photochromic derivatives of indigo: historical overview of development, challenges and applications

• Gökhan Kaplan,
• Zeynel Seferoğlu and
• Daria V. Berdnikova

Beilstein J. Org. Chem. 2024, 20, 228–242, doi:10.3762/bjoc.20.23

• . 2, 57076 Siegen, Germany 10.3762/bjoc.20.23 Abstract The importance of indigo dyes is constantly increasing with the evolution of novel textile materials and photochromic material technologies. The aim of this review article is to provide a comprehensive overview of the development of photochromic

• indigo derivatives from the first report on the photochromic N,N'-diacetylindigo in 1954 until now. We begin with the list of historical milestones in the development of photochromic indigo derivatives. Further, we provide a brief description of the synthetic procedures utilised to obtain indigo and its

• derivatives, outline the structural peculiarities, photophysical and photochemical properties of indigo and proceed with the detailed discussion of the photochromic indigo derivatives. Finally, we highlight the photochromism of the structural isomers of indigo (isoindigo and indirubin) and provide an overview

Synthesis of 5-unsubstituted dihydropyrimidinone-4-carboxylates from deep eutectic mixtures

• Sangram Gore,
• Sundarababu Baskaran and
• Burkhard König

Beilstein J. Org. Chem. 2022, 18, 331–336, doi:10.3762/bjoc.18.37

• Information File 4: Experimental procedures, characterization of products, copies of NMR spectra. Funding We thank CSIR and DST (New Delhi) for financial support and DST-FIST (New Delhi) for infrastructure facility. S.G. thanks IIT Madras, INDIGO (Indian-German exchange programme of the German Academic

Icilio Guareschi and his amazing “1897 reaction”

• Gian Cesare Tron,
• Alberto Minassi,
• Giovanni Sorba,
• Mara Fausone and
• Giovanni Appendino

Beilstein J. Org. Chem. 2021, 17, 1335–1351, doi:10.3762/bjoc.17.93

• studies on naphthalene and the conversion of naphthalene to phthalides, a reaction that, two decades later, became of critical relevance for the industrial synthesis of indigo. It is surprising that, after spending only three years in Siena, Guareschi obtained, in 1879, the prestigious Chair of Medicinal

Regioselective chemoenzymatic syntheses of ferulate conjugates as chromogenic substrates for feruloyl esterases

• Olga Gherbovet,
• Fernando Ferreira,
• Apolline Clément,
• Mélanie Ragon,
• Julien Durand,
• Sophie Bozonnet,
• Michael J. O'Donohue and
• Régis Fauré

Beilstein J. Org. Chem. 2021, 17, 325–333, doi:10.3762/bjoc.17.30

• ] and (ii) spontaneous oxidation and subsequent dimerization forming the insoluble blue 5-bromo-4-chloro-substituted indigo dye [15]. In an alternative demonstration, 1a was also used for colony level detection of FAE using yeast cells (Yarrowia lipolytica [30]) that actually coexpressed AnFaeA and

Dawn of a new era in industrial photochemistry: the scale-up of micro- and mesostructured photoreactors

• Emine Kayahan,
• Mathias Jacobs,
• Leen Braeken,
• Leen C.J. Thomassen,
• Simon Kuhn,
• Tom van Gerven and
• M. Enis Leblebici

Beilstein J. Org. Chem. 2020, 16, 2484–2504, doi:10.3762/bjoc.16.202

• indigo carmine, diclofenac, and benzoylecgonine. The reactor volume was 0.15 mL [36]. The PSTY of the photodegradation of indigo carmine was calculated as 0.01 mol·day−1·kW−1 (Table 1, entry 8). In another study, those microcapillary films were used to synthesize ascaridole, an antimalarial drug, from α

Visible-light-induced addition of carboxymethanide to styrene from monochloroacetic acid

• Kaj M. van Vliet,
• Nicole S. van Leeuwen,
• Albert M. Brouwer and
• Bas de Bruin

Beilstein J. Org. Chem. 2020, 16, 398–408, doi:10.3762/bjoc.16.38

• compound, with applications ranging from thickening agents (carboxymethyl cellulose, E466) [1][2], herbicides (2,4-dichlorophenoxyacetic acid), cosmetics (cocamidopropyl betaine), dyes (indigo vat dye) [3], to pharmaceuticals (ibuprofen, glycine, malonates) [4] (see Figure 1). Many reactions with

Design, synthesis and investigation of water-soluble hemi-indigo photoswitches for bioapplications

• Daria V. Berdnikova

Beilstein J. Org. Chem. 2019, 15, 2822–2829, doi:10.3762/bjoc.15.275

• Daria V. Berdnikova Department Chemie–Biologie, Organische Chemie II, Universität Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany 10.3762/bjoc.15.275 Abstract A series of hemi-indigo derivatives was synthesized and their photoswitching properties in aqueous medium were studied. The

• dimethoxy hemi-indigo derivative with the best photochromic performance in water was identified as a promising platform for the development of photoswitchable binders for biomolecules. The synthetic approach towards the introduction of the alkylamino pendant to the dimethoxy hemi-indigo core was developed

• that allowed to obtain an RNA-binding hemi-indigo derivative with photoswitchable fluorescent properties. Keywords: hemi-indigo; molecular switches; photochromism; photoswitching; visible light; water solubility; Introduction The application of organic photochromes in biological systems is fraught

Hyper-reticulated calixarene polymers: a new example of entirely synthetic nanosponge materials

• Alberto Spinella,
• Marco Russo,
• Antonella Di Vincenzo,
• Delia Chillura Martino and
• Paolo Lo Meo

Beilstein J. Org. Chem. 2018, 14, 1498–1507, doi:10.3762/bjoc.14.127

• (bromocresol green, 8), a bis-indole (indigo carmine, 9) and a naphthalene-bis-diazoic (naphthol blue-black, 10), in order to evaluate the outcome of molecular size, shape and electric charge. Dyes can be considered suitable and easily detectable models of pollutants [43][44][45][46][47], for the removal of

• possible positive charge on the polymeric lattice, whereas the opposite is found with anionic methyl orange (7) and bromocresol green (8). However, the anomalous datum for the large indigo carmine dianion 9 at pH 10.7, suggests that other factors may come into play, probably depending on the peculiar size

Active site diversification of P450cam with indole generates catalysts for benzylic oxidation reactions

• Paul P. Kelly,
• Anja Eichler,
• Susanne Herter,
• David C. Kranz,
• Nicholas J. Turner and
• Sabine L. Flitsch

Beilstein J. Org. Chem. 2015, 11, 1713–1720, doi:10.3762/bjoc.11.186

• ) fingerprinting of these libraries against substrates for a broad substrate panel, activity and chemo-, regio- and stereoselectivity. The production of indigo from indole derivatives 1–4 by P450s can be considered as an effective visual screen for identifying interesting new mutants from diverse libraries. Indole

• . Based on previous studies [10][11], the Tyr96Phe variant of P450cam was chosen as the template for screen development and subsequent mutagenesis. Thus, ≈16,500 colonies containing P450cam[Tyr96Phe]-RhFRed variants were rapidly screened for indigo formation (Figure 1, right), from which 93 new variants

• catalysis [21][27][28][29]. The retention of an OH group at position 252 is consistent with this important catalytic function. Indigo positive variants in library III substituted Met184 for Cys but also six of the other eleven NDT residues. Aliphatic residues Val, Leu and Ile in libraries IV, VI and VII

Deproto-metallation of N-arylated pyrroles and indoles using a mixed lithium–zinc base and regioselectivity-computed CH acidity relationship

• Mohamed Yacine Ameur Messaoud,
• Ghenia Bentabed-Ababsa,
• Madani Hedidi,
• Aïcha Derdour,
• Floris Chevallier,
• Yury S. Halauko,
• Oleg A. Ivashkevich,
• Vadim E. Matulis,
• Laurent Picot,
• Valérie Thiéry,
• Thierry Roisnel,
• Vincent Dorcet and
• Florence Mongin

Beilstein J. Org. Chem. 2015, 11, 1475–1485, doi:10.3762/bjoc.11.160

• , vincamine, ergotamine, lysergic acid), as well as in pharmaceuticals (e.g., indomethacin, iprindole), agrochemicals (e.g., auxins, pyroquilon), and dyes and pigments (e.g., indigo, indocyanines) [1][2]. The deprotonative metallation [3][4][5][6][7] is a valuable tool for the regioselective functionalization

Further exploration of the heterocyclic diversity accessible from the allylation chemistry of indigo

• Alireza Shakoori,
• John B. Bremner,
• Mohammed K. Abdel-Hamid,
• Anthony C. Willis,
• Rachada Haritakun and
• Paul A. Keller

Beilstein J. Org. Chem. 2015, 11, 481–492, doi:10.3762/bjoc.11.54

• Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), 113 Phaholyothin Road, Klong1, Klong Luang, Pathumanthani 12120, Thailand 10.3762/bjoc.11.54 Abstract Diversity-directed synthesis based on the cascade allylation chemistry of indigo, with its

• -closing metathesis of the N,O-diallylic spiro structure and subsequent Claisen rearrangement gave rise to the new (1R,8aS,17aS)-rel-1,2-dihydro-1-vinyl-8H,17H,9H-benz[2',3']pyrrolizino[1',7a':2,3]pyrido[1,2-a]indole-8,17-(2H,9H)-dione heterocyclic system. Keywords: allylation; cascade reactions; indigo

• explored is to take cheap and readily available structurally advanced starting materials and induce cascade reactions to produce relatively complex heterocycles. For example, initial exploratory studies on the base-induced N-alkylation chemistry of readily available indigo (1) with functionalised alkyl

Attempts to prepare an all-carbon indigoid system

• Şeref Yildizhan,
• Henning Hopf and
• Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 363–372, doi:10.3762/bjoc.11.42

• Braunschweig, Germany, Fax: (+49)531-391-5387 10.3762/bjoc.11.42 Abstract First attempts are described to prepare a precursor for an all-carbon analog of indigo, the tetracyclic triene 4. Starting from indan-2-one (9) the α-methylene ketone 13 was prepared. Upon subjecting this compound to a McMurry coupling

• dimerized to 30, the conversion of this olefin to 14 failed. Keywords: α-methylene ketones; Cope rearrangement; cross-conjugation; indigo; McMurry coupling; Introduction Cross-conjugated organic molecules are defined as unsaturated systems containing two π-electron systems (or lone pairs) that are in

• converted into cross-conjugated organic salts during the color-generating process. This is illustrated by indigo (1, Scheme 1) and its derivatives (e.g., Tyrian purple) and the triphenylmethane-derived carbocations. Starting from the generalized indigoid structure 2, the role of the heteroatoms X and Y can