A general synthetic route to beta-lactam-fused enediynes by intramolecular Kinugasa reaction has been successfully developed. The method has widened the scope of Kinugasa reaction in the synthesis of sensitive systems like the one described in this communication.
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http://dx.doi.org/10.1039/b605743h | DOI Listing |
Chemistry
November 2024
School of Chemistry and Chemical Engineering, Shandong University, Jinan, 250100, China.
The β-lactam scaffolds are the prevalent structural units in antibiotics and natural products. Herein, three-component asymmetric Kinugasa/aldol and Kinugasa/Mannich cascade reactions have been developed for constructing α-quaternary chiral β-lactams. This method involved the tandem reaction of alkynes, nitrones and aldehydes (or imines), resulting in the formation of three sequential stereocenters controlled by copper(I) catalysts and chiral bis(oxazolidine) ligands.
View Article and Find Full Text PDFOrg Lett
June 2024
College of Pharmacy, Jinan University, No. 601 Huangpu Avenue West, Guangzhou, 510632, P. R. China.
A mild copper-catalyzed asymmetric Kinugasa/Michael addition cascade process is developed. The reaction of α, β-unsaturated ester-tethered propiolamides with nitrones provides an efficient protocol for the construction of functionalized chiral 2,6-diazaspiro[3.4]octane-1,5-dione products in satisfactory yields and with high enantio- and diastereoselectivities.
View Article and Find Full Text PDFOrg Lett
December 2023
Davenport Research Laboratories, Department of Chemistry, University of Toronto, 80 St. George Street, Toronto, Ontario M5S 3H6, Canada.
We report an enantioselective copper-catalyzed Kinugasa/aldol domino reaction. This strategy enables access to a range of spirocyclic β-lactam pyrrolidinones in a stereoselective fashion. Under mild reaction conditions, prochiral alkyne-tethered ketones are coupled with nitrones to enable the facile construction of two spirofused ring systems containing three continuous stereocenters with excellent enantioselectivity.
View Article and Find Full Text PDFAnaerobe
December 2023
Department of Gastrointestinal Surgery, Tokyo Medical and Dental University Graduate School of Medical and Dental Sciences, 1-5-45 Yushima, Bunkyo-ku, Tokyo, Japan. Electronic address:
Introduction: Bacteroides fragilis (B. fragilis) is considered to act in an anti-inflammatory manner on the intestinal tract. On the contrary, enterotoxigenic B.
View Article and Find Full Text PDFHum Vaccin Immunother
August 2023
Clinical Epidemiology Research Center, SOUSEIKAI Medical Group (Medical Co. LTA), Fukuoka, Japan.
Although mRNA coronavirus disease 2019 (COVID-19) vaccines have been reported for high effectiveness against symptoms, it remains unclear whether post-vaccination infections are less symptomatic than infections in vaccine-naive individuals. We included patients with COVID-19 diagnosed by polymerase chain reaction tests during Japan's alpha and delta variant epidemics. COVID-19 symptoms at approximately 4 weeks were compared based on COVID-19 vaccination status.
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