(±)-Pratenone A (1), the first representative of natural 3-(1-naphthyl)-2-benzofuran-1(3H)-one polyketides, was isolated from a marine-derived Streptomyces pratensis strain KCB-132 together with three other new analogues (2-4). Its structure was assigned by spectroscopic analysis, and the absolute configurations of the two enantiomers separated by high-performance liquid chromatography were determined by single-crystal X-ray diffraction and electronic circular dichroism calculations. The solvent-induced racemization of 1 and a proposed biogenetic pathway to 1-4 from the co-isolated angucyclinone precursor, as well as their biological activity, are also discussed.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1002/chir.23178 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Cobalt-Catalyzed Enantioselective Reductive Coupling of Imines and Internal Alkynes.
Angew Chem Int Ed Engl
January 2025
IISER Kolkata: Indian Institute of Science Education and Research Kolkata, Department of Chemical Sciences, Mohanpur, 741246, Nadia, INDIA.
Chiral allyl amines are important structural components in natural products, pharmaceuticals, and chiral catalysts. Herein, we report a cobalt-catalyzed enantioselective reductive coupling of imines with internal alkynes to synthesize chiral allyl amines. The reaction is catalyzed by a cobalt complex derived from commercially available bisphosphine ligand utilizing zinc as the electron donor.
View Article and Find Full Text PDFDiastereoselective Substitution Reactions of Acyclic Acetals Controlled by Remote Participation of an Acyloxy Group.
Org Lett
December 2024
Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, United States.
A remote carbonyl group up to six atoms away from the acetal group can induce 1,2-asymmetric induction in nucleophilic substitution reactions of acyclic acetals. Isolation of a cyclic carbonate under Lewis acidic conditions and computational studies suggested that the remote carbonyl group participated through the formation of a cyclic dioxocarbenium ion intermediate. The stereochemical outcomes depended on the size of the alkyl substituent and that of the nucleophile employed.
View Article and Find Full Text PDFConcise Asymmetric Total Syntheses of (+)-Dihydropleurotinic Acid and (-)-Pleurotin, Enabling Rapid Late-Stage Diversification.
JACS Au
November 2024
Laboratory of Medicinal Chemical Biology, Department of Medicinal Chemistry, College of Pharmaceutical Sciences, Soochow University, 199 Ren'ai Road, Suzhou 215123, China.
(-)-Pleurotin () and (+)-dihydropleurotinic acid () are benzoquinone meroterpenoids isolated from fungal sources with powerful antitumor and antibiotic activities. Concise asymmetric total syntheses of the stereochemically pure (+)-dihydropleurotinic acid () and (-)-pleurotin () from the chiral pool ()-Roche ester-derived vinyl bromide have been achieved in 12 and 13 longest linear steps, respectively. The key transformations feature a Michael addition/alkylation cascade reaction to forge three contiguous stereocenters matched with the natural products, a PtO-catalyzed stereoselective reduction of olefin to generate the correct stereocenter at C3, a palladium-catalyzed Negishi cross-coupling between triflate and zinc reagent to introduce the redox-sensitive para-quinone moiety, and a hydroboration/copper-catalyzed carboxylation sequence to incorporate the vital carboxyl group.
View Article and Find Full Text PDFBrønsted Acid-Catalyzed, Asymmetric Allenoate Claisen Reaction.
J Org Chem
December 2024
Keck Science Department, Scripps, Claremont McKenna, and Pitzer Colleges, Claremont, California 91711, United States.
An auxiliary-based protocol is described for an asymmetric allenoate Claisen rearrangement. Silicated tosic acid (10 mol %) was used as an inexpensive, user-friendly catalyst. Stereochemical analysis revealed a preferential attack at the face of prostereogenic olefin.
View Article and Find Full Text PDFMultiwavelength Optical Rotation Detection: An Effective Approach for the Recognition of Analytical and Semi-Preparative HPLC Enantioseparation of the Chiral Pheromone Olean and Its Stereochemical Characterization.
Chirality
November 2024
Centre for the Control and Evaluation of Medicines, Istituto Superiore di Sanità, Rome, Italy.
Olean is the chiral spiroacetal sex pheromone of the female olive fruit fly Bactrocera oleae. Laboratory tests have demonstrated that the (R)-(-)-olean enantiomer is active on males, whereas females respond to (S)-(+)-olean. Here we present the first HPLC enantioseparation of olean using polysaccharide derivatives as chiral stationary phases and a polarimetric detector equipped with a micro-flow cell capable of detecting optical rotation at six different wavelengths.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!