A highly adaptable method targeting the ubiquitous and very important pyrrolizidine and indolizidine scaffolds is presented. The general synthetic utility of the method is underscored by its application to the rapid and easy synthesis of five natural products starting from readily accessible alkylfuran precursors. These unprotected primary furylalkylamines are subjected to photooxygenation conditions, which initiate a complex cascade reaction sequence concluding with the production of high value motifs. This sequence can be tailored to need by varying the choice of both photosensitizer and base additive.
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http://dx.doi.org/10.1002/anie.201600988 | DOI Listing |
RSC Chem Biol
September 2024
Department of Chemistry, School of Natural and Computing Sciences, University of Aberdeen Aberdeen AB24 3UE UK
The Baeyer-Villiger monooxygenase (BVMO), LgnC, plays a crucial role in the biosynthesis of bacterial pyrrolizidine alkaloids, legonmycins. It processes bicyclic indolizidine substrates generated from the coordinative action of two non-ribosomal peptide synthetases (LgnB and LgnD) and the standalone type II thioesterase-like enzyme (LgnA). It has been demonstrated that the enzyme selectively inserts molecular oxygen into the carbon-carbon bond adjacent to the carbonyl group in legonindolizidines to form bicyclic 1,3-oxazepine carbamate intermediates.
View Article and Find Full Text PDFOrg Biomol Chem
March 2023
Department of Inorganic Chemistry and Catalysis, Shahid Beheshti University, G.C., Tehran 19839 69411, Iran.
In the present study, a library of important enantiopure dispirooxindole [indolizidine, pyrrolizidine, and pyrrolidine] derivatives with three or four contiguous and two quaternary stereogenic centers using different amino acids (pipecolic acid, sarcosine, proline and hydroxyproline) were synthesized in high yields (up to 96%) through a regio- and diastereoselective (up to 99 : 1) multicomponent 1,3-dipolar cycloaddition strategy. Based on the results, the alteration of amino acids led to a change in the regioselectivity and unusual regioisomers (pyrrolizidine indolizidine/pyrrolidine) were obtained to construct a novel enantiopure 1,3-dispirooxindole skeleton. The stereochemical outcome of the cycloaddition was determined by single crystal X-ray diffraction analysis and the self-disproportionation of enantiomers (SDE) test confirmed the enantiomeric purity of the desired products.
View Article and Find Full Text PDFMolecules
February 2023
Natural Product Laboratory, Institute of Biology, Leiden University, Sylviusweg 72, 2333 AG Leiden, The Netherlands.
The presence of endophytes in plants is undeniable, but how significant their involvement is in the host plant biosynthetic pathways is still unclear. The results reported from fungicide treatments in plants varied. Fungicide treatment in was found to decrease the taxol content.
View Article and Find Full Text PDFJ Org Chem
March 2022
Tianjin Key Laboratory of Molecular Optoelectronic Science, Department of Chemistry, School of Science, Tianjin University, Tianjin 300072, P. R. China.
A novel tetrahydroxydiboron and nickel chloride cocatalyzed radical cyclization cascade with a broad substrate scope and an ultrashort reaction time was developed. The mechanistic investigation indicated that the reaction might involve a homocleavage of tetrahydroxydiboron and nickel hydride intermediates. This approach enables the simple and efficient synthesis of a series of heteropolycycles.
View Article and Find Full Text PDFOrg Biomol Chem
August 2021
Institute of Organic Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
An efficient method for the synthesis of bicyclic iminosugars has been developed. The strategy is based on the partial reduction of sugar-derived lactams by Schwartz's reagent and tandem stereoselective nucleophile addition dictated by Woerpel's model which affords polyhydroxylated cyclic amines as key intermediates. Introduction of a vinyl or allyl group to the iminosugar produces diene derivatives that can be subjected to the ring-closing metathesis reaction (RCM) to furnish polyhydroxylated pyrrolizidine, indolizidine and quinozilidine derivatives in good to excellent yields.
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