1122-25-4Relevant academic research and scientific papers
Base-promoted ring expansion of 3-aminopyrimidine-2-thiones into 1,2,4-triazepine-3-thiones
Fesenko, Anastasia A.,Shutalev, Anatoly D.
, p. 2560 - 2573 (2016/04/26)
A base-promoted ring expansion of 3-amino-4-hydroxyhexahydropyrimidine-2-thiones into 2,4,5,6-tetrahydro-3H-1,2,4-triazepine-3-thiones has been developed. Experimental data and DFT calculations showed that the reaction proceeded through fast formation of intermediate acyclic isomers of pyrimidines followed by their slow cyclization into triazepines. The starting hydroxypyrimidines were prepared by reaction of α,β-unsaturated ketones or β-alkoxy ketones with HNCS followed by treatment of the obtained β-isothiocyanato ketones with hydrazine. Triazepine-3-thiones were transformed into their 3-oxo analogs by oxidation with H2O2 under basic conditions.
SOME ASPECTS OF THE REACTIONS OF SILYL ENOL ETHERS WITH 1,3-DIOXACYCLOALKANES
Amerkhanov, R. R.,Gal'chenko, E. P.,Musavirov, R. S.,Rakhmankulov, D. L.
, p. 468 - 470 (2007/10/02)
1,3-Dioxacycloalkanes react with silyl enol ethers like linear acetals. The yield of the unsaturated ketone is influenced by the type and size of the substituent in the second position of the ring. Formals do not undergo the above-mentioned reaction.
NEW DEVELOPMENTS OF THE WHARTON TRANSPOSITION
Dupuy, C.,Luche, J. L.
, p. 3437 - 3444 (2007/10/02)
The synthetically useful Wharton transposition can be improved by using a more adequate procedure in the critical step of the intermediate α-epoxyhydrazone cleavage.Either for stable hydrazones or unstable ones, the yield of the transposed allylic alcohol is increased by treatment under anhydrous conditions with highly basic reagents (KDA in the former case, NEt3 in the latter).
α-Haloalkanesulfonyl Bromides in Organic Synthesis. 3. α-Alkylidene Ketones and 1,3-Oxathiole 3,3-Dioxides from Trimethylsilyl Enol Ethers
Block, Eric,Aslam, Mohammad,Iyer, Rajeshwari,Hutchinson, John
, p. 3664 - 3666 (2007/10/02)
α-Alkylidene ketones and 1,3-oxathiole 3,3-dioxides can be conveniently prepared by treatment of trimethylsilyl enol ethers with α-haloalkanesulfonyl bromides followed by an amine base such as 1,5-diazabicyclonon-5-ene (DBN).
Reaction of Enamines with Acetals or Trialkyl Orthoformates Activated by Lewis Acids
Takazawa, Osamu,Kogami, Kunio,Hayashi, Kazuo
, p. 1876 - 1881 (2007/10/02)
Enamines, prepared readily from various carbonyl compounds, react with acetals or trialkyl orthoformates in the presence of Lewis acids such as BF3.OEt2 to give corresponding β-alkoxy carbonyl compounds or α-dialkoxymethyl carbonyl compounds in good yields.The reaction of dienamines with acetals or trialkyl orthoformates also selectively gives corresponding β,χ-unsaturated α-(α-alkoxyalkyl) carbonyl compounds or β,χ-unsatureted α-dialkoxymethyl carbonyl compounds in good yields.
CHEMISTRY OF ENOL ETHERS. LXVIII. SILYL ENOL ETHERS IN A MODIFIED ALDOL-CROTONIC CONDENSATION. PRODUCTION OF α,β-UNSATURATED KETONES
Makin, S. M.,Kruglikova, R. I.,Tagirov, T. K.,Kharitonova, O. V.
, p. 1075 - 1078 (2007/10/02)
By the condensation of the acetals of acetaldehyde, butyraldehyde, isobutyraldehyde, and acetone with the trimethylsilyl ethers of the enolic forms of cyclohexanone, cyclopentanone, and acetone in the presence of zinc chloride as catalyst and subsequent treatment of the reaction products with dilute hydrochloric acid the following α,β-unsaturated ketones were obtained: Ethylidene-, butylidene-, and isobutylidenecyclohexanones, the corresponding cyclopentanones, and methyl propenyl ketone.
A CONVENIENT METHOD FOR THE SYNTHESIS OF α,β-UNSATURATED CARBONYL COMPOUNDS
Mukaiyama, Teruaki,Ohsumi, Tadashi
, p. 875 - 878 (2007/10/02)
A variety of α,β-unsaturated ketones are conveniently synthesized from enaminoketones and organolithium compounds especially when the reaction is carried out in petroleum ether; this reaction provides a facile method for the synthesis of α,β,γ-trisubstituted 2-cyclopentenones in combination with the regioselective alkylation of enaminoketones.
α-Alkylation and α-alkylidenation of carbonyl compounds: Lewis acid-promoted phenylthioalkylation of o-silylated enolates
Paterson, Ian,Fleming, Ian
, p. 2179 - 2182 (2007/10/11)
The O-silylated enolates of ketones, aldehydes, esters, and lactones can be phenylthioalkylated in the presence of Lewis acids; reductive or oxidative sulphur-removal gives the regiospecifically α-alkylated or alkylidenated carbonyl compounds.
