Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis

• Stephanie G. E. Amos,
• Marion Garreau,
• Luca Buzzetti and
• Jerome Waser

Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103

• combination of eosin Y (OD13) with a sacrificial electron donor can trigger the reductive debromination of several α-carbonyl halides [53]. Riboflavin (OD11) [54] and thiaporphyrin [55] have been applied as well as organic photocatalysts for similar reductive dehalogenations. Hydrogen atom transfer

One-pot preparation of 4-aryl-3-bromocoumarins from 4-aryl-2-propynoic acids with diaryliodonium salts, TBAB, and Na₂S₂O₈

• Teppei Sasaki,
• Katsuhiko Moriyama and
• Hideo Togo

Beilstein J. Org. Chem. 2018, 14, 345–353, doi:10.3762/bjoc.14.22

• acid-catalyzed reaction of phenols and propynoic acids [22] and the (−)-riboflavin-catalyzed photochemical reaction of cinnamic acids [23] were reported recently. Moreover, the use of radical cyclization for the construction of the coumarin skeleton has become widespread. Examples include the radical

From chemical metabolism to life: the origin of the genetic coding process

• Antoine Danchin

Beilstein J. Org. Chem. 2017, 13, 1119–1135, doi:10.3762/bjoc.13.111

• , appeared after an (iso)peptide-based metabolism was commonplace. Cofactors such as pterins and riboflavin are ubiquitously present in living organisms. Precursors of these essential compounds may have been synthesised by a thioester swinging-arm pathway and phosphorylated by polyphosphate. Remarkably, in

Solvent-free, visible-light photocatalytic alcohol oxidations applying an organic photocatalyst

• Martin Obst and
• Burkhard König

Beilstein J. Org. Chem. 2016, 12, 2358–2363, doi:10.3762/bjoc.12.229

• . In this setup, thin liquid films are realized which is crucial for an effective photocatalytic conversion due to the low penetration depth of light in heterogeneous systems. Several benzylic alcohols were oxidized with riboflavin tetraacetate as photocatalyst under blue light irradiation of the

• photocatalyst has been reported yet. In this work, we present a novel milling apparatus, which we developed especially for the conversion of solid substrates. Applying this apparatus, the solvent-free oxidation of various benzylic alcohols to their corresponding carbonyl compounds using riboflavin tetraacetate

• as photocatalyst under blue light irradiation was performed. Furthermore, the oxidation of a liquid benzylic alcohol is presented as well. Results and Discussion For our investigations on solvent-free photocatalytic conversions, we chose riboflavin tetraacetate (RFTA) as photocatalyst. RFTA and

A robust synthesis of 7,8-didemethyl-8-hydroxy-5-deazariboflavin

• Matthias Bender,
• Henrik Mouritsen and
• Jens Christoffers

Beilstein J. Org. Chem. 2016, 12, 912–917, doi:10.3762/bjoc.12.89

• compound with high purity. Keywords: carbohydrates; heterocyclic compounds; protective groups; riboflavin derivatives; ribose derivatives; Introduction The deazariboflavin cofactor F420 plays an important role in bacterial methanogenesis [1][2] and was – in contrast to other, ubiquitous biological redox

Release of β-galactosidase from poloxamine/α-cyclodextrin hydrogels

• César A. Estévez,
• José Ramón Isasi,
• Eneko Larrañeta and
• Itziar Vélaz

Beilstein J. Org. Chem. 2014, 10, 3127–3135, doi:10.3762/bjoc.10.330

• avoid products containing this disaccharide, or to reduce the intake according to the level of intolerance. After taking such precautions, the symptoms usually disappear; however, milk and dairy products are a concentrated source of calcium and other nutrients (e.g., high quality proteins, riboflavin

Photo, thermal and chemical degradation of riboflavin

• Muhammad Ali Sheraz,
• Sadia Hafeez Kazi,
• Sofia Ahmed,
• Zubair Anwar and
• Iqbal Ahmad

Beilstein J. Org. Chem. 2014, 10, 1999–2012, doi:10.3762/bjoc.10.208

• Muhammad Ali Sheraz Sadia Hafeez Kazi Sofia Ahmed Zubair Anwar Iqbal Ahmad Baqai Institute of Pharmaceutical Sciences, Baqai Medical University, 51, Deh Tor, Toll Plaza, Super Highway, Gadap Road, Karachi 74600, Pakistan 10.3762/bjoc.10.208 Abstract Riboflavin (RF), also known as vitamin B2

• general scheme for the photodegradation of RF is presented. Keywords: chemical degradation; degradation products; photodegradation; riboflavin; stability; thermal degradation; Review The study of photo, thermal and chemical degradation in the stability of drugs is one of the most concerned areas in the

• use of stabilizer. In case if this is not the appropriate solution then modification of a formulation can be considered to improve the stability and shelf-life of the product. Riboflavin (RF) was discovered as a yellow green fluorescent compound and was isolated from a yellow enzyme [10]. It is

The myxocoumarins A and B from Stigmatella aurantiaca strain MYX-030

• Tobias A. M. Gulder,
• Snežana Neff,
• Traugott Schüz,
• Tammo Winkler,
• René Gees and
• Bettina Böhlendorf

Beilstein J. Org. Chem. 2013, 9, 2579–2585, doi:10.3762/bjoc.9.293

• panthothenic acid, 1 g riboflavin, 2.3 g nicotinic acid, 1.2 g pyridoxine·HCl, 0.1 g vitamin B12 for 1 L solution) for 1 L H2O, pH 7.4) supplemented with 10% XAD-16 for continued product absorption during fermentation. Cells and XAD-16 were separated from the culture broth by filtration and subsequently

Synthesis of rigidified flavin–guanidinium ion conjugates and investigation of their photocatalytic properties

• Harald Schmaderer,
• Mouchumi Bhuyan and
• Burkhard König

Beilstein J. Org. Chem. 2009, 5, No. 26, doi:10.3762/bjoc.5.26

• riboflavin 3 or compound 8. Dibenzyl phosphate esters are oxidatively cleaved by blue light irradiation (440 nm) in the presence of compounds 1 and 2 (Scheme 3). The acceleration of the reaction in acetonitrile by 1 and 2, bearing a guanidinium ion binding site with phosphate affinity, is significantly

• show that 10 mol% of flavin 2, the same amount of tetraacetyl riboflavin (3) or compound 8 catalyze the photoreaction equally well. The guanidinium ion binding site of 1 and 2 does not lead to a more effective conversion. The intermolecular interaction of the guanidinium ion binding site of compound 2

• with blue light the yield after 8 h reaction time increased further (entry 2) and was significantly higher as in the absence of a photocatalyst (entry 5). However, a comparison with tetraacetyl riboflavin (3) under identical reaction conditions showed an even more pronounced acceleration of the