- Mohangic Acids A-E, p-Aminoacetophenonic Acids from a Marine-Mudflat-Derived Streptomyces sp.
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Mohangic acids A-E (1-5) were isolated from a marine Streptomyces sp. collected from a mudflat in Buan, Republic of Korea. Comprehensive spectroscopic analysis revealed that the mohangic acids are new members of the p-aminoacetophenonic acid class. The re
- Bae, Munhyung,Moon, Kyuho,Kim, Jihye,Park, Hyen Joo,Lee, Sang Kook,Shin, Jongheon,Oh, Dong-Chan
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- Structures and Biosynthetic Pathway of Pulvomycins B-D: 22-Membered Macrolides from an Estuarine Streptomyces sp.
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Pulvomycins B-D (1-3) were discovered from an estuarine Streptomyces strain along with the known pulvomycin (4). The 22-membered macrocyclic lactone structures of 1-3 were determined based on the interpretation of NMR, UV, and MS data, the modified Mosher's method, and Kishi's bidentate chiral solvent NMR spectroscopy. Genomic analysis of the bacterial strain revealed the biosynthetic gene cluster of pulvomycin and enabled us to propose the trans-acyltransferase polyketide biosynthetic pathway. Pulvomycin D displayed potent cytotoxic activity against various cancer cell lines.
- Byun, Woong Sub,Cha, Sangwon,Cui, Jinsheng,Hwang, Sunghoon,Kal, Youngju,Kim, Eunji,Lee, Sang Kook,Moon, Kyuho,Oh, Dong-Chan,Oh, Ki-Bong,Park, Jun Young,Park, So Hyun,Riandi, Evan Setiawan,Shin, Daniel,Shin, Jongheon,Sun, Jeongyoon,Yoon, Yeo Joon
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- FACTOR XIa INHIBITORS
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The present invention provides a compound of Formula (I) and pharmaceutical compositions comprising one or more said compounds, and methods for using said compounds for treating or preventing thromboses, embolisms, hypercoagulability or fibrotic changes. The compounds are selective Factor XIa inhibitors or dual inhibitors of Factor XIa and plasma Kallikrein.
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Page/Page column 53
(2017/05/21)
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- Process intensification-assisted conversion of α,ω-alkanediols to dibromides
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The increasingly widespread applications of α,ω-dibromides motivated development of a scalable, inexpensive process to rapidly convert selected α,ω-alkanediols to the corresponding dibromides. Diols were heated with only 48% aq HBr and an organic solvent, using a Dean-Stark apparatus modified to fractionate the azeotropic distillate, thereby maintaining a higher HBr concentration and reaction rate in the pot. Intensified distillation also increased the reaction rate. Various other substrate, solvent, and parameter effects have been discovered and rationalized.
- Mekala, Shekar,Hahn, Roger C.
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supporting information
p. 630 - 632
(2015/03/03)
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- A scalable, Nonenzymatic synthesis of highly stereopure difunctional C4 secondary methyl linchpin synthons
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In response to the continuing widespread use of heterodifunctional C4 secondary methyl building blocks in asymmetric synthesis, we have developed a mole-scale, two-step synthesis of a 1:1 mixture of the diastereomers of 3-bromo-2-methyl-1-propyl camphorsulfonate (casylate). One isomer (2S) has been crystallized to >99:1 dr in ~25% yield. Equilibration of the mother liquor (enriched in 2R) to a 1:1 mixture and recrystallization significantly raises the overall yield of 2S. Applications of 2S include chemoselective Grignard coupling, enabling the very short synthesis of highly stereopure long-chain natural products containing remote, methyl-bearing stereogenic centers [e.g., (R)-tuberculostearic acid], with complete control of configuration. Also, Ag-mediated, completely chemoselective Br displacement from 2S leads to a range of >99:1 er difunctional synthons. Both applications incorporate concurrent recovery of CasO. The enantiomer of 2S can be made from commercial (1R)-10-CasOH.
- Mekala, Shekar,Hahn, Roger C.
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p. 1610 - 1617
(2015/02/19)
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- Haloalkane dehalogenase catalysed desymmetrisation and tandem kinetic resolution for the preparation of chiral haloalcohols
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Six different bacterial haloalkane dehalogenases were recombinantly produced in Escherichia coli, purified, and used to catalyse the conversion of prochiral short-chain dihaloalkanes and a meso dihaloalkane, yielding enantioenriched haloalcohols. A two-reaction one-enzyme process was established in which the desymmetrisation of a dihaloalkane is followed by kinetic resolution of the chiral haloalcohol that is produced in the first step. In case of 1,3-dibromo-2-methylpropane and 1,3-dibromo-2-phenylpropane, an increase of the enantiomeric excess of the respective haloalcohol was observed in time, leading to ee values of >97%, with analytical yields of 24 and 52%, respectively. The results show that haloalkane dehalogenases can be used for the production of highly enantioenriched haloalcohols and that in some cases product enantiopurity can be improved by allowing a two-step one-enzyme tandem reaction.
- Westerbeek, Alja,Van Leeuwen, Jan G.E.,Szymański, Wiktor,Feringa, Ben L.,Janssen, Dick B.
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experimental part
p. 7645 - 7650
(2012/09/21)
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- General Synthesis of Methyl- and Dimethyl-cyclobutanes from Simple 1,3-Diols by Phase Transfer Catalysis
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A general method is described for the preparation of methyl- and dimethyl-cyclobutanes from simple 1,3-diols.The key steps of the procedure are a phase transfer catalysed ring closure and the transformation of a carboxyl group to a methyl group.Phase transfer catalysis provides good yields in the synthesis of the cyclobutane skeleton.
- Toeroek, Bela,Molnar, Arpad
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p. 801 - 804
(2007/10/02)
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