10.1021/jo015703t
The research focuses on the synthesis of the cyclic heptapeptide Trunkamide A, a biologically active compound derived from marine organisms, specifically the colonial ascidian Lissoclinum sp. The study outlines a solid-phase approach for the total synthesis of Trunkamide A, which includes the use of a quasi-orthogonal protecting scheme with tert-butyl and fluorenyl-based groups on a chlorotrityl resin, HOAt-based coupling reagents, and cyclizations in solution. Key reactants in the synthesis process include Fmoc-protected amino acids, DIPCDI, HOBt, and DAST, among others. The synthesis involves several steps such as the preparation of reverse prenyl derivatives of Ser and Thr, introduction of a protected amino thionoacid derivative, and formation of the thiazoline ring with DAST. The synthesized product was analyzed using techniques like HPLC, ES-MS, HRMS, and NMR spectroscopy to confirm its structure and purity. The research also discusses the challenges and optimizations in the synthesis process, making it suitable for large-scale synthesis of Trunkamide A and related peptides.
10.1016/S0040-4039(98)01905-4
The research aimed to introduce a fluorine atom into the structure of 3-[2-hydroxy-3-[4-(2-methoxyphenyl)piperazin-1-yl]propyl]quinazolin-2,4-(1H, 3H)-dione (4), a compound of interest due to its partial structure similar to previously studied compounds with pharmacological activities. The study explored the reaction of 4 with diethylaminosulfur trifluoride (DAST), expecting a straightforward fluorination. However, instead of the desired product, a 1,2-migration occurred, leading to the formation of N-[2-fluoro-3-[4-(2-methoxyphenyl)piperazin-1-yl]propyl]phthalimide (11a) in 13% yield and N-[2-fluoromethyl-2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl]phthalimide (11b) in 73% yield. The reaction was proposed to proceed through a spiro-aziridinium intermediate, resulting in an unexpected migration. This discovery provides a practical approach for the preparation of 1-fluoroethylamine derivatives and contributes to the understanding of DAST-induced migrations in chemical synthesis. Key chemicals used in the process included DAST, phthalimide, glycidol, 2-methoxyphenylpiperazine, hydrazine monohydrate, isatoic anhydride, and triphosgene.
10.1016/0039-128X(83)90018-1
The research focuses on the synthesis and bioassay of monofluorinated cholesterols as potential inhibitors of hydroxylation events in ecdysone biogenesis, a key process in insect molting. The study involves the preparation of C-20, C-22, C-24, and C-25 monofluorinated cholesterols, with the aim of disrupting specific hydroxylations in the cholesterol side chain that are crucial for ecdysone production. The chemicals used in the research include various reagents such as isohexylmagnesium bromide, diethylaminosulfur trifluoride (DAST), and p-toluenesulfonic acid (TsOH) for synthesis, as well as solvents like tetrahydrofuran (THF) and methylene chloride. The study also involves the use of radioactive labeling with [26-14C] for metabolic studies. The bioassays conducted on Manduca sexta larvae showed that while most monofluorinated compounds had little effect on larval growth and development, the 24-fluorocholesterol isomer caused significant growth retardation and increased mortality.
10.1016/0008-6215(88)80166-6
This research aims to synthesize modified oligosaccharides for use as substrates in studies related to glycosidase and glycosyltransferases. The authors adopted a method described by Nakabayashi et al. to synthesize glycopyrano-oxazolines, which alleviates difficulties encountered in previous methods. They synthesized 2-methyl-(3,6-di-O-acetyl-1,2,4-trideoxy-4-fluoro-a-D-glucopyrano)-[2,1-d]-2-oxazoline (6), a previously unknown compound, and demonstrated its utility for introducing a 2-acetamido-2-deoxy-?-D-glucopyranosyl group with a fluorine atom at C-4 by synthesizing benzyl 2-acetamido-6-O-(2-acetamido-2,4-dideoxy-4-fluoro-?-D-glucopyranosyl)-2-deoxy-a-D-galactopyranoside (8). Key chemicals used include benzyl 2-acetamido-3,6-di-O-benzyl-2,4-dideoxy-4-fluoro-a-D-glucopyranoside (1) as the starting material, diethylaminosulfur trifluoride for fluorination, palladium-on-charcoal for hydrogenolysis, acetic anhydride for acetylation, and trimethylsilyl trifluoromethanesulfonate for the formation of oxazoline 6. The synthesis process involves multiple steps, including fluorination, hydrogenolysis, acetylation, and glycosylation, with the final product 8 confirmed by NMR spectroscopy. The study concludes that the adopted method is effective for synthesizing the desired modified oligosaccharides.
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