64297-64-9Relevant academic research and scientific papers
Base/Cryptand/Metal-Free Automated Nucleophilic Radiofluorination of [18F]FDOPA from Iodonium Salts: Importance of Hydrogen Carbonate Counterion
Maisonial-Besset, Aurélie,Serre, Audrey,Ouadi, Ali,Schmitt, Sébastien,Canitrot, Damien,Léal, Fernand,Miot-Noirault, Elisabeth,Brasse, David,Marchand, Patrice,Chezal, Jean-Michel
supporting information, p. 7058 - 7065 (2019/01/04)
As evidenced by the number of publications and patents published in the last years, the radiosynthesis of 6-[18F]fluoro-3,4-dihydroxy-L-phenylalanine ([18F]FDOPA) using the nucleophilic [18F]F- process remains currently a challenge for the radiochemists scientific community even if promising methods for the radiofluorination of electron-rich aromatic structures were recently developed from arylboronate, arylstannane or iodonium salt precursors. In such context, based on the use of an iodonium triflate salt precursor, we optimized a fast and efficient radiofluorination route fully automated and free from any base, cryptand or metal catalyst for the radiosynthesis of [18F]FDOPA. Using this method, this clinically relevant radiotracer was produced in 64 min, 27–38 % RCY d.c. (n = 5), >99 % RCP, >99 % ee., and high Am 170–230 GBq/μmol. In addition, this optimization study clearly highlighted the important role of a triflate-hydrogen carbonate counterion exchange during the radiolabeling process to achieve high fluorine-18 incorporation yields.
Homochiral 4-azalysine building blocks: Syntheses and applications in solid-phase chemistry
Chhabra, Siri Ram,Mahajan, Anju,Chan, Weng C.
, p. 4017 - 4029 (2007/10/03)
Anomalous amino acids not only play central roles as mimics of natural amino acids but also offer opportunities as unique building blocks for combinatorial chemistry. This paper describes the chiral syntheses and solid-phase applications of a versatile atypical amino acid, 4-azalysine (2,6-diamino-4-azahexanoic acid) 1. The syntheses of differentially protected 4-azalysine derivatives 28a-e have been developed by two efficient and inexpensive routes that start either from Garner's aldehyde 16 or the chiron (S)-Nα-Cbz-2,3-diaminopropionic acid 23. Both approaches employ the convergent modular concept and exploit reductive amination of aldehydes with amines as the key step for the fusion of the two segments. In the first route, the overall process inverts the chirality of the starting material, L-serine, and thus provides an excellent route to the unnatural D-isomers. The alternative route starting from L-asparagine provides a shorter and high-yielding route to orthogonally protected 4-azalysine derivatives. The corresponding N2-Fmoc-4-azalysines 31a-e, readily derived from the key intermediate 27, are compatible with the Fmoc-based solid-phase peptide synthesis (SPPS) and solid-phase organic chemistry (SPOC) protocols. Furthermore, the utility and versatility of another key structure, tris-Boc-4-azalysine 2 in the engineering of novel high-loading dendrimeric polystyrene resins 33 and 36, have been demonstrated. Following derivatization with the Rink amide linker 34, the stability and robustness of these resin-bound dendrimers 35 and 37 in the synthesis of small molecules using a range of reaction conditions (e.g., Mitsunobu and Suzuki reactions) have been effectively illustrated.
13C NMR Study of 2-Iodoso- and 2-Iodoxy-benzoic Acids and Their Sodium Salts
Katritzky, Alan R.,Duell, Bradley L.,Gallos, John K.
, p. 1007 - 1011 (2007/10/02)
The 13C NMR spectra for selected 2-iodosobenzoic acids, their sodium salts and the sodium salts of the corresponding iodoxybenzoic acids were measured and carbon assignments made using 2D and NOE experiments and relaxation times.Iodoso and iodoxy groups deshielded the ipso-carbon in these compounds by approximately 25 and 55 ppm, repectively, relative to the corresponding iodo compounds.The 13C NMR spectrs of the 2-iodosobenzoate anions were almost identical with those of the corresponding free acids, both possessing cyclic structures.The iodoxybenzoic acids are either insoluble in, or oxidize, suitable NMR solvents (i.e.DMSO-d6, DMF-d7).The cyclic structure postulated for iodoxybenzoate anions is supported by their 13C chemical shifts.----Key words 13C NMR 2-Iodosobenzoic acids 2-Iodoxybenzoic acids Sodium 2-iodosobenzoates Sodium 2-iodoxybenzoates
Spectrophotometric Determination of Aspirin by Transacetylation of 4-Aminophenol
Verma, Krishna K.,Jain, Archana
, p. 821 - 824 (2007/10/02)
Aspirin transacetylates 4-aminophenol, yielding acetaminophen (N-acetyl-4-aminophenol), which can be determined by its oxidation to an orange-yellow product either by iodylbenzene in acetone when the absorbance is measured at 430 nm or by photometric titration with 2-iodylbenzoate in acetone-water medium at 444 nm.Salicylic acid, salicylamide, oxyphenbutazone, caffeine, and sodium hydrogen carbonate do not interfere.Drug mixtures of acetaminophen and aspirin have been analyzed by determining acetaminophen alone directly with iodyl reagents and then determining acetaminophen plus aspirin after 4-aminophenol reaction; aspirin is found b y difference
