Refernces
10.1016/j.tet.2005.12.002
The study focuses on the synthesis and characterization of a novel cationic, chiral peptide nucleic acid (PNA) analogue known as backbone extended pyrrolidine PNA (bepPNA), which is designed for selective recognition of RNA over DNA. The bepPNA features an additional carbon atom in the backbone and a (2S,4S) geometry of the pyrrolidine ring, optimizing the internucleobase distance for triplex mode binding. The researchers used various chemicals in the synthesis process, including trans-4-hydroxy-L-proline, LiCl/NaBH4 for reduction, p-TsCl for tosylation, NaN3 for azide formation, Raney Ni for reduction, BocN3 for protection, and Pd–C catalyst for hydrogenation. These chemicals served to protect, modify, and transform the PNA structure at different stages of the synthesis. The study also involved the use of UV–Tm measurements, gel electrophoretic shift assays, and circular dichroism analysis to evaluate the binding properties of bepPNA in both triplex and duplex modes. The purpose of these chemicals and methods was to create a PNA analogue with improved binding affinity and selectivity towards RNA, which has potential applications in gene-targeted therapeutics and molecular diagnostics.
10.1016/S0040-4020(01)93166-7
The research investigates the synthesis and properties of N-nitroso derivatives of several amino acids. Sarcosine, azetidine-2-carboxylic acid, hydroxyproline, and pipecolic acid play crucial roles as the primary precursors for the synthesis of their respective N-nitroso derivatives. These derivatives are of significant interest due to their potential carcinogenic properties and their possible formation in the human stomach from dietary nitrites and amino acids. The study aims to understand the formation and characteristics of these nitrosamino acids, which could potentially be relevant to the occurrence of human cancer due to their possible formation in the mammalian stomach from dietary nitrites and amino acids. The researchers prepared these compounds and characterized them using various analytical techniques such as NMR spectroscopy, mass spectrometry, and UV absorption spectroscopy. They found that these compounds are colorless crystalline solids with high yields and are highly soluble in water and most organic solvents. The study also explored the conformational preferences of these compounds in the crystalline state and their behavior in different solvents. The findings suggest that these nitrosamino acids can decarboxylate in dilute alkali to form N-nitrosamines, which are known to be toxic and carcinogenic. The research concludes that the properties of these compounds could have significant implications for understanding the potential carcinogenic activity of nitrosamino acids formed in the human stomach.
10.1016/S0040-4039(00)96916-8
The research focuses on the attachment of the anthramycin acrylamide side chain to the pyrrolo(1,4)benzodiazepine structure via a palladium-catalyzed coupling reaction of a vinyl triflate. Anthramycin, an antitumor antibiotic, has a complex synthesis process. The study explores a more efficient route by converting the 2-keto group in the pyrrolo ring to a vinyl triflate and then coupling it with various reagents. Key chemicals involved include N-methyl isatoic anhydride, L-hydroxyproline, triflic anhydride, pyridine, tributylvinylstannane, ethyl acrylate, and palladium catalysts such as (Ph3P)2Pd and PdCl2. The methodology provides a convenient procedure for constructing anthramycin derivatives, offering a rapid entry into the pyrrolo(1,4)benzodiazepine structure with the desired side chain.
10.1016/0957-4166(95)00209-8
The study focuses on the asymmetric synthesis of all four isomers of 4-amino-4-carboxyproline, which are novel conformationally restricted analogues of glutamic acid. The researchers used trans-4-hydroxy-L-proline as the homochiral starting material and employed the Bucherer-Bergs reaction as the key step to form spirohydantoin rings. The study resulted in the successful synthesis of the target compounds (2S,4S)-3, (2S,4R)-4, and their corresponding enantiomers, with high enantiomeric purity (e.e. >95%). The structures and stereochemistries of these compounds were determined and confirmed using NMR studies, including NOE measurements and 1H-NMR spectra analyses.
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