- Stereoselective Cyclopropanation of (-)-Levoglucosenone Derivatives Using Sulfonium and Sulfoxonium Ylides
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The synthesis of tri- and tetrasubstituted cyclopropanes from 3-aryl-substituted levoglucosenones (LGO) has been developed. In contrast to the unstabilised ylide dimethylsulfonium methylide which gives epoxides from LGO via 1,2-addition, we have found that the soft nucleophile dimethylsulfoxonium methylide affords cyclopropanes in moderate yields from LGO and in excellent yields and stereoselectivity with 3-aryl LGO derivatives. The use of 1,1,3,3-tetramethylguanidine as base in DMSO to generate the ylide provided the best yields and shortest reaction times. Ester stabilised sulfonium ylides could also be used to generate tetrasubstituted cyclopropane derivatives. One of the products was converted into a cyclopropyl lactone via Baeyer-Villiger oxidation to demonstrate the utility of applying cyclopropanation chemistry to LGO. Georg Thieme Verlag Stuttgart.New York.
- Ledingham, Edward T.,Merritt, Christopher J.,Sumby, Christopher J.,Taylor, Michelle K.,Greatrex, Ben W.
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p. 2652 - 2662
(2017/06/13)
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- On the thermal Pummerer rearrangement of substituted sulfoxides
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Sulfoxides bearing thioester and ester groups at the position under heating at ca. 140C undergo Pummerer thermal rearrangement. However, for sulfonyl sulfoxide, a complex mixture of products is formed. Plausible mechanism is advanced(equation presented. 2013
- Marzorati, Liliana,Yoshikawa, Eduardo K.C.,Braga, Ataualpa A.C.,Di Vitta, Claudio
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p. 248 - 260
(2014/04/03)
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- Combinatorial synthesis of 3,5-Dimethylene substituted 1,2,4-Triazoles
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Combinatorial cyclizations of imidates and hydrazides with methylene linked R groups, generated from the corresponding nitriles and carboxylic acids, respectively, provided a large library of 3,5-dimethylene substituted 1,2,4- trizoles. 2011 Bentham Science Publishers Ltd.
- Woodard, Scott S.,Jerome, Kevin D.
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experimental part
p. 132 - 137
(2012/04/18)
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- 3-Thiolated 2-azetidinones: Synthesis and in vitro antibacterial and antifungal activities
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A series of 3-thiolated β-lactams were synthesized by [2+2] ketene-imine cycloaddition reaction from S-substituted mercaptoacetic acids and Schiff bases. Then, some of the 3-methylthio β-lactams were converted to 3-(methylsulfinyl) β-lactams and 3-(methylsulfonyl) β-lactams using m-CPBA under different reaction conditions. All the compounds were characterized by spectral data and elemental analyses and were evaluated for their in vitro antibacterial and antifungal activities against pathogenic strains including Staphylococcus aureus (Methicillin resistant strain). The preliminary screening results indicated that some of these compounds demonstrated moderate to very good antibacterial and antifungal activities.
- Zarei, Maaroof,Mohamadzadeh, Masoud
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experimental part
p. 5832 - 5840
(2011/08/10)
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- PROCESS FOR PRODUCING ESTER COMPOUND
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PROBLEM To provide an environmentally-friendly method for producing industrially an ester compound. SOLUTION The present invention is a method for producing an ester compound which comprises subjecting a carboxylic acid and an alcohol to dehydration-condensation reaction using an involatile acid catalyst and then removing the residual acid catalyst by bringing a weak basic substance into contact with the residual acid catalyst.
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Page/Page column 15-16
(2010/12/31)
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- Homolytic Alkyl Group Transfer Reaction of Photoactivated Alkylcobaloximes into Thiols
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Alkyl groups of alkylcobaloximes were transferred to alkylthiols by irradiation of alkylcobaloxime and thiol under anaerobic conditions; a radical route via homolytic substitution between alkylcobaloxime and disulfide, formed during the reaction, is proposed.
- Kijima, Masashi,Miyamori, Kiyokatsu,Sato, Takeo
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p. 4147 - 4148
(2007/10/02)
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- Synthesis of Ethyl Arylacetates by Means of Friedel-Crafts Reaction of Aromatic Compounds with Ethyl α-Chloro-α-(methylthio)acetate
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Friedel-Crafts reaction of aromatic compounds with ethyl α-chloro-α-(methylthio)acetate (1) gave ethyl α-(methylthio)arylacetates (2), which were readily converted into ethyl arylacetates (3) by reductive desulfurization with Raney nickel or zinc dust-acetic acid.The reactions were applied to the syntheses of ibufenac (5) and alclofenac (6), which are anti-inflammatory agents.
- Tamura, Yasumitsu,Choi, Hong Dae,Shindo, Hirohisa,Ishibashi, Hiroyuki
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p. 915 - 921
(2007/10/02)
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