- Novel erythromycins from a recombinant Saccharopolyspora erythraea strain NRRL 2338 pIG1: I. Fermentation, isolation and biological activity
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In a previous report, a plasmid, pIG1, which contained the loading domain from the Streptomyces avermitilis polyketide synthase (PKS), promoters from Streptomyces coelicolor and the DEBS1-TE truncated PKS from Saccharopolyspora erythraea, was integrated into the S. erythraea chromosome, effectively replacing the natural erythromycin loading domain with the avermectin loading domain. In this paper, we report the feeding of short-chained fatty acids to this recombinant strain, and its parent, NRRL 2338. Both strains incorporated exogenously supplied fatty acids to produce novel, biologically active, C-13 substituted erythromycins.
- Pacey, Michael S.,Dirlam, John P.,Geldart, Roderick W.,Leadlay, Peter F.,Mcarthur, Hamish A. I.,Mccormick, Ellen L.,Monday, Robert A.,O'Connell, Thomas N.,Staunton, James,Winchester, Toby J.
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- Highly regio- and stereoselective [3+2] cyclopentanone annulation using a 3-(alkylthio)-2-siloxyallyl cationic species
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A new synthetic method for functionalized cyclopentanones was developed on the basis of a [3+2] cycloaddition reaction of a 1-(methylthio)-2-siloxyallyl cationic species and olefins. Allyl acetates 1a and 1b, which are the precursors of the allyl cationic species, are easily prepared in three or four steps from commercially available compounds. Under the influence of EtAlCl2 or AlCl3, 1a or 1b reacted with various kinds of olefins such as enol ethers, vinyl sulfides, styrenes, and trialkylolefins to afford the corresponding cyclopentanones in good yields. It is noteworthy that the sterically more hindered regioisomer was predominantly formed in every case. Furthermore, the reactions of 1b with vinyl sulfides exhibited surprisingly high stereoselectivity, which can be rationalized by the six-membered transition state models involving an orbital interaction between the sulfur atom of the vinyl sulfate and the α-carbon of the allyl cation.
- Masuya, Keiichi,Domon, Kei,Tanino, Keiji,Kuwajima, Isao
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Read Online
- SUBSTITUTED AZACYLES AS TRMP8 MODULATORS
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Disclosed are TRPM8 modulators as defined by formula (I) for achieving a cooling effect on skin and mucousa.
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Page/Page column 88; 89
(2021/04/23)
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- Ni/Ir-Catalyzed Photoredox Decarboxylative Coupling of S-Substituted Thiolactic Acids with Heteroaryl Bromides: Short Synthesis of Sulfoxaflor and Its SF5 Analog
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Metallaphotoredox cross-coupling reactions have recently emerged as a powerful tool for the construction of C(sp2)?C(sp3) bonds between alkyl chains and aromatic systems, including electron-deficient heteroaryls, which are known to be challenging coupling partners. In this article, we disclose the Ni/Ir-catalyzed photoredox decarboxylative coupling of readily available S-substituted thiolactic acids with electron-deficient heteroaryl bromides, which resulted in the formation of simple but otherwise not easily accessible heteroarenes with alkylsulfide side chains. To demonstrate a practical use of this coupling reaction, we have shown its efficiency in the one-step synthesis of a key intermediate in the synthesis of the recently marketed insecticide Sulfoxaflor, and for the short synthesis of SF5-Sulfoxaflor.
- Kanishchev, Oleksandr S.,Dolbier, William R.
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supporting information
p. 7677 - 7681
(2017/06/06)
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- Investigation of the synthetic and mechanistic aspects of the highly stereoselective transformation of α-thioamides to α-thio-β- chloroacrylamides
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Treatment of a series of α-thioamides with N-chlorosuccinimide results in efficient transformation to the analogous α-thio-β- chloroacrylamides. The mechanistic pathway has been established through isolation and characterisation of intermediate compounds. The scope of the transformation has been explored - aryl and alkylthio substituents, primary, secondary and tertiary amides can be employed. In most instances, the chloroacrylamides are formed exclusively as the Z-stereoisomer; however, with tertiary propanamides or with amides derived from butanoic or pentanoic acid a mixture of E- and Z-stereoisomers is formed. The Royal Society of Chemistry.
- Murphy, Maureen,Lynch, Denis,Schaeffer, Marcel,Kissane, Marie,Chopra, Jay,O'Brien, Elisabeth,Ford, Alan,Ferguson, George,Maguire, Anita R.
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p. 1228 - 1241
(2008/02/03)
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- Synthesis of some sulfur-containing acylferrocenes
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Acylferrocenes containing a sulfur atom within their side chain were synthesized in good yields by Friedel-Crafts acylation of ferrocene with in situ generated acyl halides from the corresponding carboxylic acids (S-protected derivatives of thioglicolic and α- and β-mercaptopropionic acids).
- Vuki?evi?, Rastko D.,Ili?, Danijela,Ratkovi?, Zoran,Vuki?evi?, Mirjana
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p. 625 - 631
(2007/10/03)
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- MgBr2-Promoted Addition of Heterosubstituted Methylketene Silyl Acetals to Alkoxy Aldehydes. Diastereoselective Synthesis of 3,4-Syn 2-Methylene- and 2-(Alkoxymethyl)-3-hydroxy-4-alkoxy Esters
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The MgBr2-mediated addition of 2- or 3-(methylthio)-substituted ketene silyl acetals 3 and 4 to α-alkoxy and α,β-dialkoxy aldehydes, followed by oxidation and elimination of methanesulfenic acid, gave 3,4-syn 2-methylene-3-hydroxy-4-alkoxy esters 9 and 11 with very high stereoselectivity (up to 100:1) and in good chemical yields.The same diastereofacial selection is at work in the analogous additions of ketene methyl silyl acetal 5, which affords 3,4-syn 2--3-hydroxy-4-alkoxy esters 12-15.
- Bernardi, Anna,Cardani, Silvia,Colombo, Lino,Poli, Giovanni,Schimperna, Giuliana,Scolastico, Carlo
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p. 888 - 891
(2007/10/02)
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- Mass Spectrometry of 2-Alkylthio-2-methylpropanoic Acids and Their Esters and Amides. Structural and Steric Effects on the McLafferty Rearrangement
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The electron ionization mass spectra (MS) of S-methylated derivatives of N-(2-mercapto-2-methylpropanoyl)-L-cysteine and 2-alkylthio-2-methylpropanoic acids, as well as their esters and amides, were examined.Use of the deuterium labeling technique and accurate mass measurement supported the proposed fragmentation pathways.Extensive loss of CH2S from a molecular ion by the McLafferty rearrangementof a primary hydrogen is important in the MS of S-methyl compounds of amide derivatives.It was demonstrated that the intensity of the rearrangement ion decreases in the order of amide, ester, and acid, and in the case if amides the reaarangement is suppressed by the nonbonded interaction between methyl groups on the α carbon and the amide nitrogen.Keywords-N-(2-mercapto-2-methylpropanoyl)-L-cysteine; 2-alkylthio-2-methylpropanoic acid and methyl ester; 2-alkylthio-2-methylpropanamide; electron impact mass spectrometry; McLafferty rearrangement; steric interaction
- Mori, Yuji,Fujiwara, Shigeru,Miyachi, Toshiko,Kitanishi, Hiroyuki,Oya, Masayuki,et al.
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p. 1505 - 1517
(2007/10/02)
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- O,O-diethyl-O-carboxamidophosphate esters
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Mites and insects, particularly aphids, are combated by applying as pest control agents one or more compounds of the structural formula EQU1 in which R is tert.butylphenyl; tert.butyl; 3,5-dimethylphenyl; 1-methyl-1-phenylthioethyl; 1-methyl-1-methylthioethyl; 1-cyclohexylthio-1-methylethyl; 1-cyclohexylthiopropyl; 1-ethylthio-1-methylethyl; 1-ethylthiopropyl or 1-ethylthioethyl.
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