We have successfully improved the fluorescence quantum yield of isoindolo[2,1-a]quinoline derivatives by suppressing the rotation of the phenyl groups at positions 5 and 11 (or 13). Additionally, we found that the planarity of these phenyl groups at positions 5 and 11 (or 13) of isoindolo[2,1-a]quinoline derivatives is crucial for two-photon absorption properties.
View Article and Find Full Text PDFThis contribution describes the development of chemoenzymatic one-pot processes, which combine an oxidative rearrangement and a biotransformation catalyzed by an imine reductase (IRED), for the synthesis of highly enantiomerically enriched secondary amines, such as an aryl-substituted pyrrolidine and a benzazepine. The benefits of this chemoenzymatic one-pot approach include high overall conversions (up to >99%), high enantiomeric excesses (up to >99% ), and a straightforward synthetic approach toward secondary amines without the need to isolate the formed intermediate. For the initial chemical reaction, namely, the oxidative rearrangement, PhI(OAc) in methanol is used as a non-natural reagent, whereas the enzymatic step requires only stoichiometric amounts of d-glucose along with catalytic amounts of IRED, glucose dehydrogenase (GDH), and the cofactor NADPH.
View Article and Find Full Text PDFWe report a perchloric acid-catalyzed heteroannulation for the synthesis of spirocyclobutanes using vinyloxyphenylbicyclobutanes with water. This metal-free reaction yields high product outputs and is consistent with the formation of a cyclobutene intermediate originating from an isomerization of a bicyclobutane.
View Article and Find Full Text PDFBis-indole alkaloids from marine sponges are an intriguing class of natural products with a variety of activities. However, only a preliminary biological study of tulongicin A (), a related previously isolated marine tris-indole alkaloid, has been conducted. In this study, we accomplished the first asymmetric total synthesis of via the construction of an imidazoline-linked bis-indolylmethane skeleton using a Friedel-Crafts-type reaction.
View Article and Find Full Text PDFThe fungal genus is a rich source of structurally diverse secondary metabolites with remarkable pharmaceutical properties. The chemical constituents and anticancer activities of the marine-derived fungus have never been investigated. In this study, a bioactivity-guided investigation led to the isolation of eleven compounds, including trichodermamide A (), trichodermamide B (), aspergillazine A (), DC1149B (), ergosterol peroxide (), cerebrosides D/C (), 5-hydroxy-2,3-dimethyl-7-methoxychromone (), nafuredin A (), and harzianumols E/F (/).
View Article and Find Full Text PDFThe adjustment of the main helical scaffold in helicenes is a fundamental strategy for modulating their optical features, thereby enhancing their potential for diverse applications. This work explores the influence of helical elongation (n = 5-9) on the structural, photophysical, and chiroptical features of symmetric oxa[n]helicenes. Crystal structure analyses revealed structural variations with helical extension, impacting torsion angles, helical pitch, and packing arrangements.
View Article and Find Full Text PDFA novel chiral borinic acid (CBA), an organocatalyst possessing a binaphthyl skeleton, was designed and synthesized. The synthesis of CBA was achieved with a 72% yield in four steps starting with optically pure 1,1'-bi-2-naphthol. The asymmetric catalytic activity was investigated in the desymmetrization of -1,2-diol.
View Article and Find Full Text PDFSulfonyl indoles were synthesized by migratory cycloisomerization from the allene -tosyl--allenylaniline. 3-Tosyl indoles or 4-tosyl indoles were selectively produced using a Pd catalyst or a Au catalyst, respectively.
View Article and Find Full Text PDFWe report the heteroannulations of bicyclobutane derivatives bearing enol ether groups in the presence of HO under mild conditions. The reaction affords spirocyclobutanes with cyclic acetal groups the Au-catalyzed hydration of the enol ether group and subsequent intramolecular cyclization.
View Article and Find Full Text PDFStructurally simplified analogues of ansellone A, in which the decalin skeleton is replaced with a lipophilic chain, were prepared and their HIV latency-reversing activities biologically evaluated. In particular, two analogues bearing ether and alkenyl side chains, respectively, showed comparable activities to that of ansellone A. Each of the simplified compounds was easily synthesized using Prins cyclisation chemistry.
View Article and Find Full Text PDFWe designed and synthesized novel 4-acetoxypentanamide derivatives of spliceostatin A, whose 4-acetoxypentenamide moiety is reduced (7), isomerized (8), or substituted with methyl at the α-position (9). The results of biological evaluation against AR-V7 and the docking analysis of each derivative suggest that the geometry of the 4-acetoxypentenamide moiety of spliceostatin A is important for its biological activity.
View Article and Find Full Text PDFMigratory cycloisomerization using transition metal catalyst is useful for synthesizing substituted heterocyclic compounds. We achieved palladium-catalyzed migratory cycloisomerization of 3-o-alkynylphenoxy acrylic acid ester derivatives to give 2,3-disubstituted benzofurans. Although there are several reports of benzofuran synthesis with palladium-catalyzed migratory cycloisomerization, migratory groups are limited to allyl and propargyl groups.
View Article and Find Full Text PDFChemical diversification of substances present in natural product extracts can lead to a number of natural product-like compounds with a better chance of desirable bioactivities. The aim of this work was to discover unprecedented chemical conversion and produce new compounds through a one-step reaction of substances present in the extracts of marine sponges. In this report, a new unnatural tetracyclic bromopyrrole-imidazole derivative, -6-Et-cylindradine A (), was created from a chemically diversified extract of the sponge sp.
View Article and Find Full Text PDFThis paper provides the first report of the intramolecular [2+2] cycloaddition of vinylsilane. The [2+2] cycloaddition of allenes is a useful reaction that can synthesize cyclobutanes. However, no previous works have attempted to control the regioselectivity between the two double bonds of allenes only by changing the reaction conditions, although there have been some reports of the regioselective [2+2] cycloaddition of allenes by changing the substrate.
View Article and Find Full Text PDFThe first total synthesis of marine sesterterpenoid ansellone G () was accomplished. This strategy utilizes the Prins cyclization reaction of a chloro-substituted homoallyl alcohol to synthesize the hydrobenzopyran skeleton. The preintroduction of the chloro groups facilitated the functional group transformation for after constructing the carbon framework.
View Article and Find Full Text PDFA double ring expansion strategy for constructing fused 3-benzazepines is described. The oxidative ring expansion of spiroamine compounds with -chlorosuccinimide and subsequent ring expansion of the resulting ketiminium ion intermediates with trimethylsilyldiazomethane afforded fused 3-benzazepines in a one-pot operation. Importantly, the Dolby-Weinreb enamine, which is a key synthetic intermediate for harringtonine alkaloids, cephalotaxines, can be accessed from commercial materials in only two steps using our developed method.
View Article and Find Full Text PDFMonoamine oxidase B (MAO-B) metabolizes monoamines such as dopamine regarding neural transmission and controls its level in the mammalian's brain. When MAO-B metabolizes dopamine abnormally, normal neurotransmission does not occur, and central nervous system disorders such as Parkinson's disease may develop. Although several MAO inhibitors have been developed, most of them have no selectivity between monoamine oxidase A (MAO-A) and MAO-B, or they work irreversibly against the enzyme.
View Article and Find Full Text PDFMultitasking single-catalyst systems that allow multiple chemical transformations within a single reaction vessel are important for the development of eco-compatible chemistry. Here, we have developed a rhodium-catalyzed system that transforms 1-(allyloxy)-2-(cyclopropylmethyl)benzene derivatives to 2-ethyl-3-isopropylbenzofurans double isomerization/cycloisomerization/aromatization.
View Article and Find Full Text PDFThe absolute structure of an indole alkaloid (+)-cinchonaminone by total synthesis of both (+)-cinchonaminone and its enantiomer was determined. The main focus of the study was the enantioselective synthesis of both enantiomers of a chiral -3,4-disubstituted piperidine. We also evaluated monoamine oxidase (MAO) inhibitory activities of these enantiomers.
View Article and Find Full Text PDFThe aim of this study was to evaluate bitterness by using "CCDP; Change in concentration-dependent potential" considering dose-dependency of active pharmaceutical ingredients (APIs) as new and useful bitterness evaluation index compared with bitter sensor output value which is conventional bitterness evaluation index for 48 pediatric medicines from the recent edition of the WHO model list of essential medicines for children (7th edn, 2019). Solutions (0.01, 0.
View Article and Find Full Text PDFWe have developed a one-iridium-catalyst system that transforms -allyl--sulfonyl-2-(silylalkynyl)aniline derivatives, which are 1,7-enynes in which both multiple bonds have a heteroatom, to the corresponding substituted indole derivatives via isomerization/cycloisomerization/aromatization. This strategy provides an atom-economical and straightforward synthetic approach to a series of valuable indoles having vinyl and silylmethyl groups at the 2- and 3-positions.
View Article and Find Full Text PDFBackground/aim: Indoleamine 2,3-dioxygenase (IDO) is regarded as an important molecular target for cancer immune therapy. This study aimed to examine the IDO1 inhibitory activity of newly synthesized indomethacin derivatives to develop an IDO1 inhibitor.
Materials And Methods: The inhibitory effects of indole-containing compounds against recombinant human IDO1 (rhIDO1) were evaluated.
The total synthesis and biological evaluation of the marine sesterterpenoid ansellone A (), an HIV latency-reversing agent, and its analogues are reported. The key to the success of this synthetic route is a Prins cyclization reaction enabled by the strategic use of the TfO group for stabilization of the acid-labile tertiary allylic alcohol. The SAR study found the alcohol analogue to exhibit more potent activity than .
View Article and Find Full Text PDFα,β-Unsaturated esters were selectively protected in situ in the presence of α,β-unsaturated Weinreb amides using PEt and trimethylsilyl trifluoromethanesulfonate (TMSOTf) in toluene under reflux. Diisobutylaluminium hydride (DIBAL-H) reduction of the mixture followed by tetra-n-butylammonium fluoride (TBAF) treatment produced α,β-unsaturated aldehydes in good yields along with the recovered α,β-unsaturated esters.
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