- A short and effective synthesis of dimethyl 2-methoxycarbonyl-3-methylenesuccinate
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Cycloaddition of ketene dimethyl acetal (7) to dimethyl butynedioate (8) followed by electrocyclic ring opening yields diene 10. This can be hydrolyzed readily to the title compound 1.
- Dehmlow,Veretenov
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- Synthesis of mimosamycin
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Mimosamycin (1) was synthesized in eight steps with an overall yield of 13% from 2-methoxy-3-methyl-1,4-benzoquinone by regioselective introduction of a chloromethyl group at C-6 and a methoxycarbonylmethyl group at C-5 and subsequent reaction of the intermediate methyl (o- (chloromethyl)phenyl)acetate derivative 16 with methylamine. Oxidation of the 5,7,8-trimethoxy-2,6-dimethyl-1,4-dihydroisoquinoline-3(2H)-one 17 thus obtained, using cerium(IV) ammonium nitrate as a selective oxidizing agent, gave mimosamycin (1) in good overall yield.
- Kesteleyn, Bart,De Kimpe, Norbert
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p. 635 - 639
(2007/10/03)
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- An Intramolecular Element Effect in Nucleophilic Vimylic Substitution Reactions
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Fluorochloro- and fluorobromoethenes CHX=CFX (X = Cl, Br) in reactions with sodium alkoxides RONa (R = Me, Et, i-Pr, t-Bu) in the corresponding alcohols afford the products of monosubstitution of both chlorine (bromine) and fluorine, as well as orthoesters XCH2C(OR)3 and esters XCH2COOR. The stereochemistry of the reactions and the intramolecular element effect are discussed.
- Shainyan,Danilevich
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p. 188 - 192
(2007/10/03)
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- NUCLEOPHILIC REACTIONS AT A VINYLIC CENTER. XXVIII. FLUOROCHLOROETHENES AND FLUOROBROMOETHENES IN REACTIONS WITH SODIUM ALCOHOLATES AND ARENETHIOLATES
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During the reaction of halogenoethenes (Z+E)-CHX=CFX with sodium methoxide and with sodium p-thiocresolate in methanol initial attack by the nucleophilic takes place at the carbon atom attached to the fluorine atom.In the reactions with sodium methoxide the intermediate monosubstitution products are more reactive than the initial halogenoethenes, and the main reaction products are the ortho esters CHXYC(OMe)3.An "element effect", i.e., concurrent substitution of F and Cl(Br) in the reaction with sodium methoxide, was discovered.With sodium p-thiocresolate trifluorochloroethene gives the product from substitution of the chlorine atom and a small amount of the addition product as impurity.The other ethenes give substitution, addition, and halogenophilic reduction products and also the products from further transformations (hydrolysis and decarboxylation).
- Shainyan, B. A.,Vereshchagin, A. L.
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p. 1981 - 1988
(2007/10/02)
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