10.1021/ja00524a043
The research focuses on the controlled chemical synthesis of enzymatically produced eicosanoids, specifically 11-, 12-, and 15-HETE, which are derived from arachidonic acid and are precursors to hydroperoxides (HPETEs). The purpose of the study was to develop effective and selective chemical syntheses of these biologically important compounds, filling critical gaps in previous chemical knowledge and providing multigram laboratory preparation methods. The researchers achieved this by employing new synthetic methodologies, such as the use of the magnesium derivative of isopropylcyclohexylamine (MICA) for the epoxide-allylic alcohol conversion, which proved to be superior to other reagents. Key chemicals used in the process included arachidonic acid, isopropylcyclohexylamine, methylmagnesium bromide, tetrahydrofuran (THF), sodium dihydrogen phosphate, ether, silica gel, and various other reagents for specific conversion steps. The conclusions of the research demonstrated the successful synthesis of the targeted eicosanoids and the development of new synthetic methods, which are significant for both the chemical synthesis of biologically active compounds and the understanding of enzymatic processes.
10.1021/jacs.9b03328
The research focuses on the regiocontrolled hydrogenation of polycyclic aromatic hydrocarbons (PAHs) using chromium and cobalt catalysis, which is a significant challenge due to the thermodynamic stability of PAHs arising from their aromaticity. The study employs a combination of experimental and theoretical approaches to achieve this hydrogenation at ambient temperature. The reactions are facilitated by the use of inexpensive chromium or cobalt salts, diimino/carbene ligands, and methylmagnesium bromide, leading to high regioselectivity and an expanded substrate scope, including rarely reduced PAHs like tetracene, tetraphene, pentacene, and perylene. The research provides a cost-effective and scalable catalytic protocol for hydrogenation, which can be further utilized in the synthesis of functionalized motifs such as tetrabromo and carboxyl-substituted derivatives. The experiments involve the optimization of reaction conditions, the use of various PAHs as substrates, and the analysis of products through techniques like NMR and GC. Theoretical mechanistic modeling using density functional theory (DFT) was also conducted to understand the active species involved in the hydrogenation process, suggesting that low-valent Cr and Co monohydride species, likely derived from zero-valent transition metals, mediate the hydrogenation of fused PAHs.
10.1016/j.tetlet.2010.10.098
The research focuses on the first asymmetric synthesis of (+)-amphiasterin B4, a cytotoxic metabolite isolated from a marine sponge, using a chiral pool strategy to prepare the enantiomerically pure form of this compound. The purpose of this study was to synthesize amphiasterin B4 and determine its absolute stereochemistry, which was previously unspecified. The researchers successfully synthesized (+)-amphiasterin B4, starting from a known (S)-b-benzyloxy-γ-lactone, and confirmed the identity and stereochemistry of the synthesized product by comparing it with the properties of the authentic material. The conclusion was that the absolute configurations of the naturally occurring amphiasterin B4 should be assigned as 3R, 4R, and 5S. Key chemicals used in the synthesis process included dihydroxyacetone dimer, (S)-(-)-α-methylbenzylamine, 2-phenylsulfonyl-3-phenyloxaziridine, methylmagnesium bromide, sodium borohydride, and various protecting groups such as THP, TBDPS, TBS, and catalytic reagents like PDC and PTSA.
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