“…Unless otherwise noted, all reagents were purchased from commercial suppliers and used without further purification. 5,5′-Dimethyldipyrromethane and 1,4-bis(3,4-diethyl-1 H -pyrrol-2-yl)benzene were synthesized according to the literature methods. ,,, For column chromatography, Wakogel (60N, particle size 38–100 μm, silica gel, irregular) was used. Heating of the sample solutions, if necessary, were performed with a water bath (≤50 °C) or an aluminum block bath (>50 °C).…”
The Vilsmeier reagent (VR), first reported a century ago, is a versatile reagent in a variety of organic reactions. It is used extensively in formylation reactions. However, the synthesis of VR generally requires highly toxic and corrosive reagents such as POCl 3 , SOCl 2 , or COCl 2 . In this study, we found that VR is readily obtained from a CHCl 3 solution containing N,Ndimethylformamide or N,N-dimethylacetamide upon photoirradiation under O 2 bubbling. The corresponding Vilsmeier reagents were obtained in high yields with the generation of gaseous HCl and CO 2 as byproducts to allow their isolations as crystalline solid products amenable to analysis by X-ray crystallography. With the advantage of using CHCl 3 , which bifunctionally serves as a reactant and a solvent, this photo-on-demand VR synthesis is available for one-pot syntheses of aldehydes, acid chlorides, formates, ketones, esters, and amides.
“…Unless otherwise noted, all reagents were purchased from commercial suppliers and used without further purification. 5,5′-Dimethyldipyrromethane and 1,4-bis(3,4-diethyl-1 H -pyrrol-2-yl)benzene were synthesized according to the literature methods. ,,, For column chromatography, Wakogel (60N, particle size 38–100 μm, silica gel, irregular) was used. Heating of the sample solutions, if necessary, were performed with a water bath (≤50 °C) or an aluminum block bath (>50 °C).…”
The Vilsmeier reagent (VR), first reported a century ago, is a versatile reagent in a variety of organic reactions. It is used extensively in formylation reactions. However, the synthesis of VR generally requires highly toxic and corrosive reagents such as POCl 3 , SOCl 2 , or COCl 2 . In this study, we found that VR is readily obtained from a CHCl 3 solution containing N,Ndimethylformamide or N,N-dimethylacetamide upon photoirradiation under O 2 bubbling. The corresponding Vilsmeier reagents were obtained in high yields with the generation of gaseous HCl and CO 2 as byproducts to allow their isolations as crystalline solid products amenable to analysis by X-ray crystallography. With the advantage of using CHCl 3 , which bifunctionally serves as a reactant and a solvent, this photo-on-demand VR synthesis is available for one-pot syntheses of aldehydes, acid chlorides, formates, ketones, esters, and amides.
Azobenzene derivatives due to their photo- and electroactive properties are an important group of compounds finding applications in diverse fields. Due to the possibility of controlling the trans–cis isomerization, azo-bearing structures are ideal building blocks for development of e.g. nanomaterials, smart polymers, molecular containers, photoswitches, and sensors. Important role play also macrocyclic compounds well known for their interesting binding properties. In this article selected macrocyclic compounds bearing azo group(s) are comprehensively described. Here, the relationship between compounds’ structure and their properties (as e.g. ability to guest complexation, supramolecular structure formation, switching and motion) is reviewed.
“…This second effect is the charge stabilization during repair. For both CPD- and (6-4)-photolyases the repair is initiated by electron flow from FADH - to the lesion, in case of (6-4) photoproduct the electron is initially located on the 5' thymine at position 3, 4 or 5 [21, 22]. In the quantum chemical model with His366 + the distances between the Mg 2+ ions and the isoalloxazine center of or the adenine center of FAD are 15 - 17 Å, whereas the distances between Mg 2+ and the carbon 4 of the lesion thymine are shorter, i.e.…”
Prokaryotic (6-4) photolyases branch at the base of the evolution of cryptochromes and photolyases. In the Agrobacterium (6-4) photolyase PhrB, the repair of DNA with UV-induced (6-4) pyrimidin dimers is stimulated by Mg2+. We show that Mg2+ is required for efficient lesion binding and for charge stabilization after electron transfer from the FADH- chromophore to the DNA lesion. Two highly conserved Asp residues close to the DNA binding site are essential for the Mg2+ effect. Simulations showed that two Mg2+ bind to the region around these residues. DNA repair by eukaryotic (6-4) photolyases is not increased by Mg2+. Here, the structurally overlapping region contains no Asp but positively charged Lys or Arg. During evolution, charge stabilization and DNA binding by Mg2+ was therefore replaced by a positive amino acid. We argue that this transition has evolved in a freshwater environment. Prokaryotic (6-4) photolyases usually contain an FeS cluster. DNA repair of a cyanobacterial member of this group which is missing the FeS cluster was also found to be stimulated by Mg2+.
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