- α-Methylene Cyclic Carbonate as a Conjunctive Agent for Aromatic Aldehydes
-
α-Methylene cyclic carbonate undervent dacarboxylative cycliaddition to aromatic aldehydes to yield dihydrofuranone derivatives in the presence of a dicationic palladium complex.
- Inoue, Yoshio,Matsushita, Koichi,Yen, I-Fang,Imaizumi, Shin
-
p. 1377 - 1378
(2007/10/02)
-
- A radical cyclisation route to bullatenone, a natural 3(2H)-furanone
-
A simple route to bullatenone (3) starting from styrene, via the radical cyclisation of the bromoalkyne 6 to 3-methylenetetrahydrofuran 7, is described.
- Srikrishna
-
p. 479 - 480
(2007/10/02)
-
- Stereoelectronic effects in ring closure reactions: the 2'-hydroxychalcone-flavanone equilibrium, and related systems
-
The 2'-hydroxychalcone (2-HOC6H4COCH=CHC6H4X)-flavanone equilibrium in trifluoroacetic acid (TFA) has been examined.The influence of substituents X on the rate of attainment of equilibrium shows that the 6-endo-trig mode of ring closure by Michael addition is disallowed, by demonstrating a negative ρ value for the reaction rate when X is varied.Reaction therefore proceeds either on the carbonyl-protonated form, which allows twisting about the 2,3 double bond, its double bond character being reduced by resonance, or through direct rate-limiting protonation on the 2,3-double bond.Either pathway permits the allowed 6-exo-trig mode of ring closure to be followed.Alternative mechanism involving intermolecular Michael addition of trifluoroacetate, followed by intramolecular 6-exo-tet displacement are considered.Such Michael adducts can be detected in the ring closures of 2-crotonyl-4-methylphenol and 4,4-dimethyl-1-(2-hydroxyphenyl)-2-penten-1-one in TFA, but they do not appear to lie on the main pathway, because the reaction proceed with equal facility in methanesulphonic acid/chloroform medium, which does not contain a suitable nucleophile for such a mechanism.Further important mechanistic information is given by studying the reactions in TFA-d, together with measurements on the (E)-2-methyl-3-oxo-5-arylpent-4-en-2-ol and flight during the rate-limiting step, and provide evidence against the mechanism involving a preequilibrium carbonyl protonation, such as in the Nazarov rearrangement of 3'-methoxychalcones, where KH/kD is ca. 0.7.Some results are also reported for ring closure of the 2-aminochalcones in TFA.
- Brennan, Colin M.,Hunt, Ian,Jarvis, Terence C.,Johnson, C. David,McDonnell, Peter D.
-
p. 1780 - 1785
(2007/10/02)
-
- Rhodium Acetate Catalyzes the Addition of Carbenoids α- to Ether Oxygens
-
Diazo-carbonyl compounds, when catalyzed by rhodium acetate, insert preferentially adjacent to ether oxygens.This phenomenon was exploited to develop a synthesis of 3(2H)-furanones.
- Adams, Julian,Poupart, Marc-Andre,Grenier, Louis,Schaller, Chris,Ouimet, Nathalie,Frenette, Richard
-
p. 1749 - 1752
(2007/10/02)
-
- Regiocontrolled Formation of 4,5-Dihydro-3(2H)-furanones from 2-Butyne-1,4-diol Derivatives. Synthesis of Bullatenone and Geiparvarin
-
Two new methods for selective hydration of 1,1,4-trisubstituted 2-butyne-1,4-diols (1) to give 4,5-dihydro-3(2H)-furanone derivatives are reported.The first involves selective monoacetylation of the less hindered hydroxyl group of 1 followed by Ag(I)-cata
- Saimoto, Hiroyuki,Hiyama, Tamejiro,Nozaki, Hitosi
-
p. 3078 - 3087
(2007/10/02)
-
- Reversal of Electronic Effects between Inter- and Intra-molecular Michael Addition Reactions
-
Measurement of the rates of cyclisation of (E)-2-methyl-3-oxo-5-phenylpent-4-en-2-ol and its p-methoxy-derivative in trifluoroacetic acid, together with the rates of the reverse reaction, indicates an influence of stereoelectronic origin which is not present in intermolecular Michael additions.
- Ellis, Graham W. L.,Johnson, C. David,Rogers, David N.
-
-
- Synthesis and Reactions of Simple 3(2H)-Furanones
-
Interest in the total synthesis of natural product antitumor agents which have as a central structural element the 3(2H)-furanone ring system has led to the development of an efficient general synthesis of a variety of simple 3(2H)-furanones.The strategy
- Smith, Amos B.,Levenberg, Patricia A.,Jerris, Paula J.,Scarborough, Robert M.,Wovkulich, Peter M.
-
p. 1501 - 1513
(2007/10/02)
-
- Synthesis of functionalized tetrahydrofurans
-
A novel cyclization reaction is described which affords readily manipulable 3(2H)-dihydrofuranone ethylene ketals, useful in the total synthesis of an ascofuranone model, bullatenone, and muscarine analogs.
- Semple, J.Edward,Guthrie, Anne E.,Joullie, Madeleine M.
-
p. 4561 - 4564
(2007/10/02)
-