Synthesis and Antifungal Activity of Chromones and Benzoxepines from the Leaves of Ptaeroxylon obliquum

Abstract

This study reports the first total synthesis of the bioactive oxepinochromones 12-O-acetyleranthin (8) (angular isomer) and 12-Oacetylptaeroxylinol (9) (linear isomer). The antifungal activity of these compounds and their derivatives was determined against Candida albicans and Cryptococcus neoformans. Most compounds had good selectivity between the two fungi and showed moderate to good activity. 12-O-Acetyleranthin ( 8) had the highest activity against C. albicans, with an MIC value of 9.9 μM, while 12-O-acetylptaeroxylinol ( 9), the compound present in Ptaeroxylon obliquum, had the highest activity against C. neoformans, with an MIC value of 4.9 μM.

8‐Prenylflavanones through Microwave Promoted Tandem Claisen Rearrangement/6‐endo‐trig Cyclization and Cross Metathesis

“…[ 68 ] The compound has previously been synthesized through oxa‐Michael cyclization of a prenylated chalcone [ 17 ] and via regioselective enzyme catalyzed prenylation of eriodictyol. [ 69 ] Our synthesis started with the known compounds 9c [ 70 ] and 10e , [ 71 ] which were reacted in a Claisen‐Schmidt condensation under the previously established conditions to furnish 11ce . Microwave promoted tandem Claisen‐rearrangement/6‐endo‐cyclization of 11ce gave a separable mixture of MOM‐protected flavanone 12ce and uncyclized chalcone 13ce in a combined yield of 67 %.…”

“…Microwave reactions were carried out in an Anton‐Paar‐monowave‐300 or an Anton‐Paar‐monowave‐400 reactor (monowave, maximum power 850 W, temperature control by IR‐sensor, vial volume 20 mL). These starting materials were synthesized following literature procedures: 9a , [ 20 ] 9b , [ 22 ] 9c [ 70 ] and 10e . [ 71 ]…”

Solvent‐Free Microwave‐Assisted Multicomponent Synthesis of 4H‐Chromenes Using Fe3O4‐Based Hydrotalcites as Bifunctional Catalysts

“…Generally, these procedures involve a high atom economy and in most of the cases allow multiple‐bond forming transformations (MBFTs) under mild reaction conditions [2] . In particular, 4 H ‐chromenes are oxa‐heterocyclic compounds with a remarkable role in medicinal chemistry and drug discovery due to their broad spectrum of biological activities, including antimicrobial, [3] anti‐inflammatory, [4] antibacterial, [5] anticancer, [6] antifungal, [7] among others [8] . In this regard, MCRs have gained considerable attention for assembling structurally diverse 4 H ‐chromenes in a rapid, step‐economic, and eco‐friendly manner [9] .…”

Novel Thiochromanone Derivatives Containing a Sulfonyl Hydrazone Moiety: Design, Synthesis, and Bioactivity Evaluation

“…As early as the late 19th century, Khellin was extracted from the fruit of the Umbellifera, which was widely distributed in eastern Mediterranean countries, and was used as the first chromone drug in clinical applications [ 5 ]. Meanwhile, biological activity results showed that both natural and synthetic chromone compounds had a wide range of biological activities, such as antifungal [ 6 , 7 ], antibacterial [ 6 ], anticancer [ 8 ], and antiviral [ 9 ] activity. Thiochromanone, a kind of chromone compound, is an important substance in the synthesis of various active molecules that are extensively used in the intermediate skeleton of drugs and has attracted more and more attention due to their extensive biological activities, including antiviral [ 10 ], antibacterial [ 11 , 12 ], antifungal [ 11 , 13 , 14 , 15 ], herbicidal [ 16 , 17 ], and insecticidal [ 18 ] activity.…”