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Yongjia Shang - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Isocoumarins from cyclic 2 diazo 1 3 diketones and benzoic acids via rh iii catalyzed c h activation and esterification
Journal of Organic Chemistry, 2017Co-Authors: Cheng Yang, Lanlan Zhang, Guang Han, Youpeng Zuo, Yongjia ShangAbstract:A mild and efficient Rh(III)-catalyzed C–H activation/esterification reaction for the synthesis of Isocoumarins has been developed. This procedure uses readily available benzoic acids and cyclic diazo-1,3-diketones as starting materials and involves domino intermolecular C–H activation in combination with intramolecular esterification to give the corresponding Isocoumarins in moderate to excellent yields. This process provides a facile approach for the construction of Isocoumarins containing various functional groups that does not require any additives.
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Synthesis of Isocoumarins from Cyclic 2‑Diazo-1,3-diketones and Benzoic Acids via Rh(III)-Catalyzed C–H Activation and Esterification
2017Co-Authors: Cheng Yang, Lanlan Zhang, Guang Han, Youpeng Zuo, Yongjia ShangAbstract:A mild and efficient Rh(III)-catalyzed C–H activation/esterification reaction for the synthesis of Isocoumarins has been developed. This procedure uses readily available benzoic acids and cyclic diazo-1,3-diketones as starting materials and involves domino intermolecular C–H activation in combination with intramolecular esterification to give the corresponding Isocoumarins in moderate to excellent yields. This process provides a facile approach for the construction of Isocoumarins containing various functional groups that does not require any additives
James C. Powers - One of the best experts on this subject based on the ideXlab platform.
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Mechanism-Based Isocoumarin Inhibitors for Blood Coagulation Serine Proteases. Effect of the 7-Substituent in 7-Amino-4-chloro-3-(isothioureidoalkoxy)Isocoumarins on Inhibitory and Anticoagulant Potency
Journal of medicinal chemistry, 1994Co-Authors: Chih-min Kam, John E. Kerrigan, R. Richard Plaskon, Edward J. Duffy, Pete Lollar, F. L. Suddath, James C. PowersAbstract:A series of 7-amino-4-chloro-3-(3-isothioureidopropoxy)Isocoumarin (NH2-CiTPrOIC) derivatives with various substituents at the 7- and 3-positions have been synthesized as inhibitors of several blood coagulation enzymes. Isocoumarins substituted with basic groups such as guanidino or isothioureidoalkoxy groups were previously shown to be potent irreversible inhibitors of blood coagulation enzymes [Kam et al. Biochemistry 1988, 27, 2547-2557]. Substituted Isocoumarins with an isothioureidoethoxy group at the 3-position and a large hydrophobic group at the 7-position are better inhibitors for thrombin, factor VIIa, factor Xa, factor XIa, factor IIa, and factor IXa than NH2-CiTPrOIC (4). PhNHCONH-CiTEtOIC (14), (S)-Ph(CH3)CHNHCONH-CiTEtOIC (25), and (R)-Ph(CH3)CHNHCONH-CiTEtOIC (26) inhibit thrombin quite potently and have kobs/[I] values of (1-4) x 10(4) M-1 s-1. Modeled structures of several Isocoumarins noncovalently complexed with human alpha-thrombin suggest that H-bonding between the 7-substituent and the Lys-60F NH3+ relates to the inhibitory potency. Thrombin inhibited by 14, 25, or 26 is quite stable, and only 4-16% of enzymatic activity is regained after incubation for 20 days in 0.1 M Hepes, pH 7.5 buffer. However, 100, 67, and 65% of enzyme activity, respectively, is regained with the addition of 0.38 M hydroxylamine. With normal citrated pig or human plasma, these Isocoumarin derivatives prolong the prothrombin time ca. 1.3-3.1-fold and also prolong the activated partial thromboplastin time more than 3-7-fold at 32 microM. Thus, these compounds are effective anticoagulants in vitro and may be useful in vivo.
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[31] Isocoumarin inhibitors of serine peptidases
Methods in enzymology, 1994Co-Authors: James C. Powers, Chin-min KamAbstract:Publisher Summary This chapter describes Isocoumarin inhibitors of serine peptidases. Isocoumarins are mechanism-based or “suicide” inhibitors wherein the Isocoumarin ring is opened by the active site serine residue of a serine peptidase to form an acyl-enzyme derivative. A new reactive structure is unmasked, which can react further with an active site nucleophile to form an alkylated acyl-enzyme derivative, a doubly covalent enzyme-inhibitor complex. 3, 4-dichloroiscoumarin (DCI) is a general serine peptidase inhibitor that inhibits most serine peptidases and many esterases. DCI is quite specific and will not inhibit metalloexopeptidases such as leucine aminopeptidase or β-lactamase. DCI is prepared by cyclization of homophthalic acid with PCl 5 in POCl 3 to give 3-chloroIsocoumarin, which is then converted to 3, 3, 4-trichloro-3, 4-dihydroIsocoumarin by reaction with Cl 2 . Elimination of HCl from the trichloro derivative gives 3,4-dichloroIsocoumarin. Substituted Isocoumarins inhibit serine peptidases irreversibly and the inhibition rates can be measured by the incubation method under pseudo-first-order conditions or by the progress curve method in the presence of the substrate.
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structural study of porcine pancreatic elastase complexed with 7 amino 3 2 bromoethoxy 4 chloroIsocoumarin as a nonreactivatable doubly covalent enzyme inhibitor complex
Biochemistry, 1991Co-Authors: J. Vijayalakshmi, Edgar F Meyer, James C. PowersAbstract:: The complex of porcine pancreatic elastase (PPE) with 7-amino-3-(2-bromoethoxy)-4-chloroIsocoumarin, a potent mechanism-based inhibitor, was crystallized and the crystal structure determined at 1.9-A resolution with a final R factor of 17.1%. The unbiased difference Fourier electron density map showed continuous density from O gamma of Ser 195 to the benzoyl carbonyl carbon atom and from N epsilon 2 of His 57 to the carbon atom at the 4-position of the Isocoumarin ring in the inhibitor. This suggested unambiguously that the inhibitor was doubly covalently bound to the enzyme. It represents the first structural evidence for irreversible binding of an Isocoumarin inhibitor to PPE through both Ser 195 and His 57 in the active site. The PPE-inhibitor complex is only partially activated in solution by hydroxylamine and confirms the existence of the doubly covalently bound complex along with the acyl enzyme. The benzoyl carbonyl oxygen atom of the inhibitor is not situated in the oxyanion hole formed by the amide (greater than NH) groups of Gly 193 and Ser 195. The complex is stabilized by the hydrogen-bonding interactions in the active site (from the N epsilon 2 of Gln 192 to the bromine atom in the inhibitor and the amino group at the 7-position of the Isocoumarin ring to the carbonyl oxygen of Thr 41) and by van der Waals interactions. The inhibition rates of several 7-substituted 4-chloro-3-(bromoalkoxy)Isocoumarins toward PPE were measured.(ABSTRACT TRUNCATED AT 250 WORDS)
Wei Dong - One of the best experts on this subject based on the ideXlab platform.
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versicolols a and b two new prenylated Isocoumarins from endophytic fungus aspergillus versicolor and their cytotoxic activity
Archives of Pharmacal Research, 2017Co-Authors: Min Zhou, Kun Zhou, Yuede Wang, Wei Dong, Jie Lou, Xuemei GaoAbstract:Versicolols A and B (1 and 2), two rare prenylated Isocoumarin derivatives, along with five known Isocoumarins (3–7) were isolated from the fermentation products of an endophytic fungus Aspergillus versicolor. Their structures were elucidated on the basis of extensive spectroscopic analysis, including 1D- and 2D-NMR techniques. Compounds 1 and 2 were evaluated for their cytotoxicity against five human tumor cell lines. The results showed that compounds 1 exhibited weak cytotoxicity against A549 and MCF7 cells with IC50 values of 9.4 and 8.8 μm, and compound 2 exhibited weak cytotoxicity against SHSY5Y and MCF7 cells with IC50 values of 8.2 and 6.8 μm, respectively.
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antiviral and cytotoxic Isocoumarin derivatives from an endophytic fungus aspergillus oryzae
Planta Medica, 2016Co-Authors: Min Zhou, Kun Zhou, Kunmiao Wang, Ruizhi Zhu, Yuede Wang, Wei DongAbstract:Oryzaeins A–D ( 1 - 4 ), four new Isocoumarin derivatives, along with five known ones ( 5 - 9 ) were isolated from solid cultures of an endophytic fungus Aspergillus oryzae . Their structures were elucidated by detailed spectroscopic analysis and by comparison with reported data of related derivatives. Among them, compounds 1 and 2 represent the first examples of Isocoumarins possessing an unusual 2-oxopropyl group and a rare 3-hydroxypropyl group. Compounds 1 and 2 displayed moderate anti-tobacco mosaic virus activities with inhibition rates of 28.4 % and 30.6 %, respectively, at the concentration of 20 µM. The new compounds showed moderate inhibitory activities against several human tumor cell lines with IC 50 values in the range of 2.8–8.8 µM. Supporting information available online at http://www.thieme-connect.de/products
Takao Tanahashi - One of the best experts on this subject based on the ideXlab platform.
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A 14-Membered Macrolide and Isocoumarin Derivatives from the Cultured Lichen Mycobionts of Graphis vestitoides.
ChemInform, 2013Co-Authors: Hoang Hoang, Yukiko Takenaka, Nobuo Hamada, Hiromi Miyawaki, Takao TanahashiAbstract:Isocoumarin (I) and the 14-membered macrolide ((S)-II) are isolated along with five known Isocoumarin derivatives.
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A 14-membered macrolide and Isocoumarin derivatives from the cultured lichen mycobionts of Graphis vestitoides.
Chemical & pharmaceutical bulletin, 2012Co-Authors: Yukiko Takenaka, Nobuo Hamada, Hiromi Miyawaki, Takao TanahashiAbstract:Spore-derived mycobionts of the crustose lichen Graphis vestitoides collected in Vietnam were cultivated on a malt-yeast extract medium supplemented with 10% sucrose. The investigation of their metabolites resulted in isolation of a novel 14-membered macrolide and a new Isocoumarin, together with five known Isocoumarin derivatives. Their structures were determined by spectroscopic and chemical means. This is the first instance of isolation of a 14-membered macrolide from a lichen mycobiont.
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Phenolic compounds from the cultured mycobionts of Graphis proserpens.
Phytochemistry, 2011Co-Authors: Yukiko Takenaka, Nobuo Hamada, Natsuko Morimoto, Takao TanahashiAbstract:Spore-derived mycobionts of the lichen Graphis proserpens were cultivated on a malt-yeast extract medium supplemented with 10% sucrose and their metabolites were investigated. Isocoumarin derivatives 1-3 and 7-oxo-5,7-dihydrooxepino[4,3,2-de]isochromene derivatives, proserins A-C (4-6), were isolated along with three known Isocoumarin derivatives and three benzoic acid derivatives. Their structures were determined by spectroscopic methods.
Cheng Yang - One of the best experts on this subject based on the ideXlab platform.
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synthesis of Isocoumarins from cyclic 2 diazo 1 3 diketones and benzoic acids via rh iii catalyzed c h activation and esterification
Journal of Organic Chemistry, 2017Co-Authors: Cheng Yang, Lanlan Zhang, Guang Han, Youpeng Zuo, Yongjia ShangAbstract:A mild and efficient Rh(III)-catalyzed C–H activation/esterification reaction for the synthesis of Isocoumarins has been developed. This procedure uses readily available benzoic acids and cyclic diazo-1,3-diketones as starting materials and involves domino intermolecular C–H activation in combination with intramolecular esterification to give the corresponding Isocoumarins in moderate to excellent yields. This process provides a facile approach for the construction of Isocoumarins containing various functional groups that does not require any additives.
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Synthesis of Isocoumarins from Cyclic 2‑Diazo-1,3-diketones and Benzoic Acids via Rh(III)-Catalyzed C–H Activation and Esterification
2017Co-Authors: Cheng Yang, Lanlan Zhang, Guang Han, Youpeng Zuo, Yongjia ShangAbstract:A mild and efficient Rh(III)-catalyzed C–H activation/esterification reaction for the synthesis of Isocoumarins has been developed. This procedure uses readily available benzoic acids and cyclic diazo-1,3-diketones as starting materials and involves domino intermolecular C–H activation in combination with intramolecular esterification to give the corresponding Isocoumarins in moderate to excellent yields. This process provides a facile approach for the construction of Isocoumarins containing various functional groups that does not require any additives
