The synthesis of two conformationally constrained lysine analogues is reported. The synthesis of the novel analogue 1 based on the 3-aza-bicyclo[3.1.0]hexane system is accomplished from the known tricycle 3 in eight steps. The synthesis of the analogue 2 is accomplished in eight steps from 4-hydroxy proline. Both analogues are synthesized appropriately protected for Fmoc/Boc solid-phase peptide synthesis.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1021/jo060210f | DOI Listing |
Chemistry
December 2024
Southern University of Science and Technology, Chemistry, 1088 Xueyuan Avenue, 518055, Shenzhen, CHINA.
The convergent total synthesis of ixabepilone and its analogues in a 13-step longest linear sequence is reported. The crucial chiral centers at challenging C3-O, C8-C and C15-N positions on the scaffold of the ixabepilone were installed via highly efficient asymmetric hydrogenations (up to 95% yield and up to 99% e.e.
View Article and Find Full Text PDFJ Org Chem
December 2024
Chemistry and Materials Program, College of Engineering, Shibaura Institute of Technology, 3-7-5 Toyosu, Kohto-ku, Tokyo 135-8548, Japan.
Both enantiomers of 2-ethylquinazolin-4-ones bearing -CHO/CDO and CHO/CHO phenyl groups at the N3 position were prepared. These are isotopic atropisomeric compounds based on a remote and conformationally flexible H/D and C/C discrimination, and it was found that a CHCl solution of -CHO/CDO derivative shows a slight specific optical rotation. Furthermore, diastereomeric quinazolinone derivatives bearing a chiral carbon were prepared, and their stereochemical purities and rotational stability as well as the isotopic atropisomerism were verified by H NMR and chiral high-performance liquid chromatography (HPLC) analyses.
View Article and Find Full Text PDFInorg Chem
December 2024
Department of Chemistry, University of Kansas, 1567 Irving Hill Road, Lawrence, Kansas 66045, United States.
Both cyclic "crown" and acyclic "tiara" polyethers have been recognized as useful for the binding of metal cations and enabling the assembly of multimetallic complexes. However, the properties of heterobimetallic complexes built upon acyclic polyethers have received less attention than they deserve. Here, the synthesis and characterization of a family of eight redox-active heterobimetallic complexes that pair a nickel center with secondary redox-inactive cations (K, Na, Li, Sr, Ca, Zn, La, and Lu) bound in acyclic polyether "tiara" moieties are reported.
View Article and Find Full Text PDFTetrahedron Lett
March 2024
Department of Chemistry, University of California, Berkeley, CA 94720, United States.
In this manuscript, an oxidative carbon-carbon bond forming reaction to construct the framework of alkaloids such as scholarinine A is explored using a constrained substrate. Instead of the desired carbon-carbon bond formation between an indole C3 position and a malonate group, a competing carbon-nitrogen bond between the malonate and indole C3 position was observed to form. This work adds to the growing body of substrates for oxidative carbon-carbon bond formation and importantly, demonstrates that these reactions are challenging for some conformationally constrained substrates.
View Article and Find Full Text PDFBottlebrush polymers are complex architectures with densely grafted polymer side chains along polymeric backbones. The dense and conformationally extended chains in bottlebrush polymers give rise to unique properties, including low chain entanglement, low critical aggregation concentrations, and elastomeric properties in the bulk phase. Conjugated polymers have garnered attention as lightweight, processible, and flexible semi-conducting materials.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!