- Use of the Nonionic Superbase P(MeNCH2CH2)3N in the Selective Monoalkylation of Active-Methylene Compounds
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The symmetric active-methylene compounds CH2(CO2Et)2 and CH2[C(O)Me]2 are selectively monoalkylated in the presence of 1.1 equiv of a variety of alkyl halides and 1 equiv of the nonionic Superbase P(MeNCH2CH2)2N in 85-98% yields in 30 min at room temperature. The unsymmetrical active-methylene compound EtO2CCH2C(O)Me is selectively monoalkylated under the same conditions, except for the temperature, which is 0 °C, in 59-88% yields. The observation of selective C- rather than O-alkylation is rationalized in terms of the formation of an enolate whose negatively charged oxygen is sterically protected by a nearby HP(MeNCH2CH2)2N+ counterion in a tight ion pair.
- Arumugam, Subramaniam,McLeod, Dale,Verkade, John G.
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p. 3677 - 3679
(2007/10/03)
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- On Triazoles XIX: The Reaction of 5-Amino-1,2,4-triazoles with Functionalized Acetoacetic Esters
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Different "functionalized" alkyl 3-oxo-butyrates (2) were reacted with 5-amino-3-Q-1H-1,2,4-triazoles (1) to yield 3 and 4 type 1,2,4-triazolopyrimidinones.In case of 2 (R1 = methyl, R2 = 1-ethoxycarbonylethyl, R3 = ethyl) beside the corresponding derivative 4 the unexpected 5,6-dihydro-6,8-dimethyl-7-ethoxycarbonyl-3-methylthio-1,2,4-triazolo-1,3-diazepin-5(9H)-one (7) was isolated, representing a novel ring system.
- Reiter, Jozsef,Pongo, Laszlo,Somorai, Tamas,Pallagi, Istvan
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p. 173 - 187
(2007/10/02)
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- A NEW ROUTE TO 2,3-DIALKYLATED CYCLOPENTENONES. AN EFFICIENT SYNTHESIS OF cis-JASMONE
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An efficient synthesis of 2,3-dialkylated cyclopentenoids, starting from acyclic precursors, is reported.The synthetic approach has been applied to the preparation of cis-jasmone.
- Cainelli, Gianfranco,Panunzio, Mauro,Plessi, Laura,Martelli, Giorgio,Spunta, Giuseppe
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p. 327 - 330
(2007/10/02)
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