80-97-7Relevant articles and documents
Ruthenium-decorated lipid vesicles: Light-induced release of [Ru(terpy)(bpy)(OH2)]2+ and thermal back coordination
Bonnet, Sylvestre,Limburg, Bart,Meeldijk, Johannes D.,Gebbink, Robertus J. M. Klein,Killian, J. Antoinette
, p. 252 - 261 (2011)
Electrostatic forces play an important role in the interaction between large transition metal complexes and lipid bilayers. In this work, a thioether-cholestanol hybrid ligand (4) was synthesized, which coordinates to ruthenium(II) via its sulfur atom and intercalates into lipid bilayers via its apolar tail. By mixing its ruthenium complex [Ru(terpy)(bpy)(4)]2+ (terpy = 2,2′;6′,2′′-terpyridine; bpy = 2,2′-bipyridine) with either the negatively charged lipid dimyristoylphosphatidylglycerol (DMPG) or with the zwitterionic lipid dimyristoylphosphatidylcholine (DMPC), large unilamellar vesicles decorated with ruthenium polypyridyl complexes are formed. Upon visible light irradiation the ruthenium-sulfur coordination bond is selectively broken, releasing the ruthenium fragment as the free aqua complex [Ru(terpy)(bpy)(OH 2)]2+. The photochemical quantum yield under blue light irradiation (452 nm) is 0.0074(8) for DMPG vesicles and 0.0073(8) for DMPC vesicles (at 25 °C), which is not significantly different from similar homogeneous systems. Dynamic light scattering and cryo-TEM pictures show that the size and shape of the vesicles are not perturbed by light irradiation. Depending on the charge of the lipids, the cationic aqua complex either strongly interacts with the membrane (DMPG) or diffuses away from it (DMPC). Back coordination of [Ru(terpy)(bpy)(OH2)]2+ to the thioether-decorated vesicles takes place only at DMPG bilayers with high ligand concentrations (25 mol %) and elevated temperatures (70 °C). During this process, partial vesicle fusion was also observed. We discuss the potential of such ruthenium-decorated vesicles in the context of light-controlled molecular motion and light-triggered drug delivery.
Method for synthesizing cholesterol by taking BA as raw material
-
, (2021/08/14)
The invention discloses a method for synthesizing cholesterol by taking BA as a raw material. A plant source raw material 21-hydroxy-20-methylpregna-4-en-3-one, also known as Shuangjiangchun or BA is taken as a raw material, and the cholesterol is synthesized by the steps of oxidation, Wittig reaction, acetylation, reduction, selective hydrogenation reduction and the like. The raw materials for synthesizing cholesterol are plant sources, the price is low, the safety is high, the risk of pathogenic bacteria and virus infection is avoided, and the synthesis method is easy to operate, high in yield, few in side reaction, environmentally friendly, good in economical efficiency and convenient for industrial production; and the invention solves the safety problem of the existing cholesterol product and the problems of high cost, environmental unfriendliness and unsuitability for large-scale industrial production in the synthesis technology.
Development of Improved Synthetic Routes to Pixatimod (PG545), a Sulfated Oligosaccharide-Steroid Conjugate
Chhabra, Mohit,Ferro, Vito,He, Qi Qi,Wimmer, Norbert
, p. 2420 - 2431 (2021/11/01)
The heparan sulfate (HS) mimetic pixatimod (PG545) is a highly potent inhibitor of angiogenesis, tumor growth, and metastasis currently in clinical trials for cancer. PG545 has also demonstrated potent antiviral activity against numerous HS-dependent viruses, including SARS-CoV-2, and shows promise as an antiviral drug for the treatment of COVID-19. Structurally, PG545 consists of a fully sulfated tetrasaccharide conjugated to the steroid 5α-cholestan-3β-ol. The reported synthesis of PG545 suffers from a low yield and poor selectivity in the critical glycosylation step. Given its clinical importance, new efficient routes for the synthesis of PG545 and analogues were developed. Particular attention was given to improving the key glycosylation step by using more stable protecting groups and optimized glycosyl donors.
Electrochemical Borylation of Alkyl Halides: Fast, Scalable Access to Alkyl Boronic Esters
Cao, Yangmin,Hu, Ping,Huang, Cheng,Liu, Zhao,Lu, Qingquan,Ma, Wan,Peng, Pan,Qi, Xiaotian,Wang, Bingbing
supporting information, p. 12985 - 12991 (2021/09/03)
Herein, a fast, scalable, and transition-metal-free borylation of alkyl halides (X = I, Br, Cl) enabled by electroreduction is reported. This process provides an efficient and practical access to primary, secondary, and tertiary boronic esters at a high current. More than 70 examples, including the late-stage borylation of natural products and drug derivatives, are furnished at room temperature, thereby demonstrating the broad utility and functional-group tolerance of this protocol. Mechanistic studies disclosed that B2cat2 serves as both a reagent and a cathodic mediator, enabling electroreduction of difficult-to-reduce alkyl bromides or chlorides at a low potential.
Copper-Catalyzed and Indium-Mediated Methoxycarbonylation of Unactivated Alkyl Iodides with Balloon CO
Chen, Yanchi,Su, Lei,Gong, Hegui
supporting information, p. 4689 - 4693 (2019/06/27)
This work emphasizes the synthesis of alkyl esters via Cu-catalyzed and In-mediated alkoxycarbonylation of unactivated alkyl iodides in the presence of In or InI. The reactions were suitable for the preparation of primary, secondary, and even tertiary alkyl esters, representing an exceptionally rare example for the creation of quaternary carbon centers upon formation of esters. The preliminary mechanistic studies indicated that alkyl radicals were involved, and Cu/In/CO played a cooperative role in the carbonylation event.
Oxidative Deprotection of p-Methoxybenzyl Ethers via Metal-Free Photoredox Catalysis
Ahn, Deok Kyun,Kang, Young Woo,Woo, Sang Kook
, p. 3612 - 3623 (2019/03/11)
An efficient and greener deprotection method for p-methoxybenzyl (PMB) ethers using a metal-free visible light photoredox catalyst and air and ammonium persulfate as the terminal oxidants is presented. Various functional groups and protecting groups were tolerated in the developed method to achieve good to excellent yields in short reaction times. Significantly, the developed method was compatible with PMB ethers derived from primary, secondary, and tertiary alcohols and a gram-scale reaction. Mechanistic studies support a proposed reaction mechanism that involves single electron oxidation of the PMB ether.
Ruthenium nanoparticles ligated by cholesterol-derived NHCs and their application in the hydrogenation of arenes
Rakers, Lena,Martínez-Prieto, Luis M.,López-Vinasco, Angela M.,Philippot, Karine,Van Leeuwen, Piet W. N. M.,Chaudret, Bruno,Glorius, Frank
supporting information, p. 7070 - 7073 (2018/07/05)
Herein we present ruthenium nanoparticles (Ru-NPs) stabilized with two rigid NHC ligands derived from cholesterol. The obtained nanoparticles were fully characterized and applied in the hydrogenation of various aromatic compounds under mild conditions. Interestingly, the more bulky ligand gives a slightly lower ligand coverage and a faster catalyst.
Addressable Cholesterol Analogs for Live Imaging of Cellular Membranes
Rakers, Lena,Grill, David,Matos, Anna L.L.,Wulff, Stephanie,Wang, Da,B?rgel, Jonas,K?rsgen, Martin,Arlinghaus, Heinrich F.,Galla, Hans-Joachim,Gerke, Volker,Glorius, Frank
, p. 952 - 12,961 (2018/05/08)
Cholesterol is an essential component of most biological membranes and serves important functions in controlling membrane integrity, organization, and signaling. However, probes to follow the dynamic distribution of cholesterol in live cells are scarce and so far show only limited applicability. Herein, we addressed this problem by synthesizing and characterizing a class of versatile and clickable cholesterol-based imidazolium salts. We show that these cholesterol analogs faithfully mimic the biophysical properties of natural cholesterol in phospholipid mono- and bilayers, and that they integrate into the plasma membrane of cultured and primary human cells. The membrane-incorporated cholesterol analogs can be specifically labeled by click chemistry and visualized in live-cell imaging experiments that show a distribution and behavior comparable with that of endogenous membrane cholesterol. These results indicate that the cholesterol analogs can be used to reveal the dynamic distribution of cholesterol in live cells. Cholesterol is an important component of biological membranes, but probes recording its dynamic intracellular distribution are scarce. Rakers et al. developed cholesterol-derived imidazolium salts mimicking properties of natural cholesterol. Following specific labeling via click chemistry, one of the cholesterol analogs was shown to incorporate into cellular membranes equivalent to endogenous cholesterol.
Efficient Water Reduction with sp3-sp3 Diboron(4) Compounds: Application to Hydrogenations, H–D Exchange Reactions, and Carbonyl Reductions
Flinker, Mathias,Yin, Hongfei,Juhl, René W.,Eikeland, Espen Z.,Overgaard, Jacob,Nielsen, Dennis U.,Skrydstrup, Troels
supporting information, p. 15910 - 15915 (2017/11/23)
A series of crystalline sp3-sp3 diboron(4) compounds were synthesized and shown to promote the facile reduction of water with dihydrogen formation. The application of these diborons as simple and effective dihydrogen and dideuterium sources was demonstrated by conducting a series of selective reductions of alkynes and alkenes, and hydrogen–deuterium exchange reactions using two-chamber reactors. Finally, as the water reduction reaction generates an intermediate borohydride species, a range of aldehydes and ketones were reduced by using water as the hydride source.
An Alkyne Diboration/6π-Electrocyclization Strategy for the Synthesis of Pyridine Boronic Acid Derivatives
Mora-Radó, Helena,Bialy, Laurent,Czechtizky, Werngard,Méndez, María,Harrity, Joseph P. A.
, p. 5834 - 5836 (2016/05/09)
A new and efficient synthesis of pyridine-based heteroaromatic boronic acid derivatives is reported through a novel diboration/6π-electrocyclization strategy. This method delivers a range of functionalized heterocycles from readily available starting materials.
