[reaction: see text] Starting from (S)-glycidol, the asymmetric total synthesis of novel D-seco Corynanthe-type oxindoles Us-7 and Us-8 was accomplished. The structure of Us-7 was revised from the reported structure 1 with the (3R,7S) form to structure 22 with (3S,7R), and the absolute stereochemistry at C15 of both alkaloids was established.
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http://dx.doi.org/10.1021/ol035128a | DOI Listing |
J Am Chem Soc
January 2025
BioCIS, Faculté de Pharmacie, Université Paris-Saclay, CNRS, Orsay 91400, France.
The endoperoxide scaffold is found in numerous natural products and synthetic substances of pharmaceutical interest. The main challenge to their synthetic access remains the preparation of chiral compounds due to the weakness of the peroxide bond, which limits the scope of available or applicable methods. Here, we demonstrate how peroxycarbenium species can be trapped by silylated nucleophiles with high enantioselectivities and diastereoselectivities when applicable, using a chiral imidophosphorimidate (IDPi) as a catalyst.
View Article and Find Full Text PDFAcc Chem Res
January 2025
Chongqing Key Laboratory of Natural Product Synthesis and Drug Research, Innovative Drug Research Center, School of Pharmaceutical Sciences, Chongqing University, Chongqing 401331, China.
ConspectusThe Mannich reaction, involving the nucleophilic addition of an enol(ate) intermediate to an imine or iminium ion, is one of the most widely used synthetic methods for the synthesis of β-amino carbonyl compounds. Nevertheless, the homo-Mannich reaction, which utilizes a homoenolate intermediate as the nucleophilic partner and provides straightforward access to the valuable γ-amino carbonyl compounds, remains underexplored. This can be largely attributed to the difficulties in generation and manipulation of the homoenolate species, despite various homoenolate equivalents that have been developed.
View Article and Find Full Text PDFAm J Sports Med
January 2025
Youth Physical Development Centre, Cardiff School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, UK.
Background: Residual interlimb deficits after anterior cruciate ligament reconstruction (ACLR) can lead to functional maladaptation and increase the risk of reinjury. The tuck jump assessment (TJA) may offer a more effective evaluation of ACLR status as compared with traditional tasks owing to increased risk of altered landing mechanics, asymmetrical landing, and increased knee valgus attributed to the cyclical nature of the task. However, it remains unclear whether altered TJA kinetics resolve over time or persist through return-to-play phases of rehabilitation.
View Article and Find Full Text PDFJ Org Chem
January 2025
Center for Catalytic Hydrocarbon Functionalizations, Institute for Basic Science (IBS) and Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea.
Described herein is our computational study to rationalize the stereoselective epimerization of α,α'--disubstituted oxolane and oxetane ketones and to the corresponding α,α'- ketones and reported in our previous total syntheses of (+)-3-()-isolaureatin () and (+)-3-()-laureatin (). Density functional theory (DFT) calculations using appropriately truncated models revealed that the α,α'- ketones are more stable than the α,α'- ketones, in very good agreement with experimental results. The computational results showed that the isomer with a longer interatomic distance between the two ring oxygen atoms was lower in energy, which suggested the presence of repulsive interactions between those oxygen atoms.
View Article and Find Full Text PDFSci Rep
January 2025
Department of Electrical Engineering, Faculty of Engineering, Al-Azhar University, Cairo, Egypt.
This article presents an innovative asymmetric multilevel inverter (MLI) topology that outperforms conventional counterparts. The introduced topology presents a breakthrough in implementing power electronics control by maximizing specific levels while minimizing switching components. A cutting-edge control scheme for optimal operation of the cascaded half-bridge MLI is presented.
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