10.1016/S0040-4039(00)87208-1
The research aimed to develop a one-pot method for converting α-aminoesters to α-ketoesters, which are valuable intermediates for enzyme inhibitor design studies. The process involved the oxidation of diazoesters using peracid, specifically m-chloroperbenzoic acid (MCPBA). The study built upon previous work by Curci and co-workers on the conversion of α-diazoketones to α-diketones and Takamura's method for converting α-aminoesters to α-diazoesters using isoamylnitrite in the presence of acetic acid. The researchers found that by replacing isoamyl nitrite with t-butyl nitrite, they could achieve a cleaner α-ketoester due to the easier removal of t-butanol. The one-pot procedure involved treating the diazotization mixture with MCPBA to directly afford the α-ketoester, avoiding the need to isolate the intermediate α-diazoesters. The study concluded that while the reaction had certain limitations, it provided a facile route for converting α-aminoesters to α-ketoesters in applicable cases. Chemicals used in the process included α-aminoesters, isoamylnitrite, t-butyl nitrite, acetic acid, and m-chloroperbenzoic acid (MCPBA).
10.1246/bcsj.59.185
The research focuses on the synthesis and evaluation of Gramicidin S (GS) analogs, specifically [3Ava5-]-GS and [3Ava4,3'-]-GS, where Ava represents 5-Aminovaleric Acid. These analogs involve replacing one or two L-leucyl-p-phenylalanyl residues of GS with 5-aminovaleric acid residues. Various chemicals played crucial roles in the synthesis process. For instance, Boc-Val-Orn(Z)-OH, H-Leu-D-Phe-Pro-OMe, and Boc-Pro-OH were used as starting materials or intermediates. Reagents like DCC (dicyclohexylcarbodimide), HOBt (1-hydroxybenzotriazole), and isopentyl nitrite were employed in coupling and conversion reactions. Solvents such as THF (tetrahydrofuran), DMF (N,N-dimethylformamide), and MeOH (methanol) were utilized in different steps of the synthesis. The study also involved the use of protecting groups like Boc (t-butoxycarbonyl) and Z (benzyloxycarbonyl), and their removal was achieved using methods involving HCI (hydrochloric acid) and Pd (palladium) catalysts. The synthesized analogs were characterized and their antimicrobial activities were assessed, revealing insights into the contributions of the amide bond and side chains in the GS structure to its antimicrobial properties.
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