Showing papers on "Enone published in 1991"
202 citations
TL;DR: In the presence of the co-catalyst NaOH (2.4 mol%), RuCl2(PPh3)3(0.1 mol%) catalyses efficient transfer hydrogenation of both aliphatic and aromatic ketones by propan-2-ol with rates up to 900 turnovers per hour at 82 °C; no hydrogenation occurs in the absence of sodium hydroxide as discussed by the authors.
Abstract: In the presence of the co-catalyst NaOH (2. 4 mol%), RuCl2(PPh3)3(0.1 mol%) catalyses efficient transfer hydrogenation of both aliphatic and aromatic ketones by propan-2-ol with rates up to 900 turnovers per hour at 82 °C; no hydrogenation occurs in the absence of sodium hydroxide.
154 citations
TL;DR: In this article, the convergent synthesis of substituted phenols is possible by nickel(0)-catalyzed ring opening and cycloaddition of cyclobutenones with alkynes.
Abstract: The results above show that the convergent synthesis of substituted phenols is possible by nickel(0)-catalyzed ring opening and cycloaddition of cyclobutenones with alkynes. Future efforts will explore application of this method to intramolecular reactions
130 citations
TL;DR: In this paper, the synthesis of epoxides 3a-r is achieved in excellent yields by reaction of the α,β-unsaturated ketones 1a-c, 4,4-disubstituted (E)-chalcones 1d-o, and 2'-hydroxy-4-substitized (E) chalcone 1p-r with isolated dimethyldioxirane (2a) (as acetone solution) and/or in situ generated ethyl(methyl) dioxiranes (2b).
Abstract: The synthesis of epoxides 3a-r is achieved in excellent yields by reaction of the α,β-unsaturated ketones 1a-c, 4,4'-disubstituted (E)-chalcones 1d-o, and 2'-hydroxy-4-substituted (E)-chalcones 1p-r with isolated dimethyldioxirane (2a) (as acetone solution) and/or in situ generated ethyl(methyl) dioxirane (2b). This method constitutes a useful alternative to the Weitz-Scheffer epoxidation (alkaline H 2 O 2 ) of such electron-poor substrates
110 citations
TL;DR: Methyl propargyl ethers, obtained from carbonyl compounds by successive treatment with an acetylide and MeI, were easily converted to the corresponding α,β-unsaturated ketone by regioselective hydration of acetylenic moiety followed by elimination of methanol under the catalytic action of Au(III) as discussed by the authors.
Abstract: Methyl propargyl ethers, obtained from carbonyl compounds by successive treatment with an acetylide and MeI, were easily converted to the corresponding α,β-unsaturated ketone by regioselective hydration of acetylenic moiety followed by elimination of methanol under the catalytic action of Au(III).
102 citations
TL;DR: The reaction cle de cette synthese totale est l'application de la reaction Becker-Alder au 5bromo-6methoxy-8-oxo-1-oxaspiro [25] octa-4,6-diene-4-carbaldehyde as discussed by the authors.
Abstract: La reaction cle de cette synthese totale est l'application de la reaction Becker-Alder au 5-bromo-6-methoxy-8-oxo-1-oxaspiro [25] octa-4,6-diene-4-carbaldehyde
96 citations
86 citations
83 citations
79 citations
TL;DR: In this paper, a rhodium-stabilized carbenoid was added to a neighboring alkene tethered on the side chain to give an indenyl-substituted bicyclo[3.1.0]hexane derivative.
Abstract: Treatment of several o-alkynyl-substituted α-diazoacetophenone derivatives with rhodium(II) carboxylates results in the formation of substituted indenones. The simplest mechanism accounting for the results involves addition of a rhodium-stabilized carbenoid onto the acetylenic π-bond to generate a vinyl carbenoid directly or possibly a highly strained cyclopropene derivative. The vinyl carbenoid was found to undergo addition to a neighboring alkene tethered on the side chain to give an indenyl-substituted bicyclo[3.1.0]hexane derivative. A number of related systems were examined so as to probe the scope and generality of the process
79 citations
TL;DR: In this article, the potential of the chiral SAr*-anion as a non-transferable group was investigated and it was shown that in the presence of a catalvtic amount of CuSAr* (9 mol%) conjugate addition with 57% e.g.
Abstract: Selective conjugate addition (0 % enantiomeric excess (e.e.)) of organo- arenethiolatocuprates (from methyl lithium and 23 l-(R)-(dimethylamino)ethyl)phenyl- thiolatocopper(I), CuSAr*) to benzylideneacetone (BA) is found up to a LiMe/CuSAr* ratio of 2/l indicating the potential of the chiral SAr*-anion as non-transferable group; at higher ratios only 1,2-addition occurs. Reactions of methyl magnesium iodide with BA in the presence of a catalvtic amount of CuSAr* (9 mol%) result in exclusive conjugate addition with 57% e.e..
TL;DR: In the presence of a catalytic amount of a palladium-phosphine complex, such as Pd(PPh3)4 or Cl2Pd(PCP3)2 treated with n-BuLi (2 equiv), cyclic α-iodoenones and α-triflyloxyenones can be conjugately reduced to the corresponding α-alkenyl ketones with complete retention of both enone regiochemistry and alkenyl stereochemistry.
TL;DR: In the presence of zinc, 3-bromo-3-3,3-difluoropropene or 3-iodo-1,1-dIFFLOROPropene reacted with carbonyl compounds to give the corresponding α,α-difi-fluorohomoallylic alcohols in good yields at 0°C to room temperature as discussed by the authors.
Abstract: In the presence of zinc, 3-bromo-3,3-difluoropropene or 3-iodo-1,1-difluoropropene reacted with carbonyl compounds to give the corresponding α,α-difluorohomoallylic alcohols in good yields at 0°C to room temperature. The reaction is applicable to aliphatic and aromatic aldehydes, dialkyl ketones, and alkyl aryl ketones. Reaction with α,β-unsaturated aldehydes and ketones yielded 1,2-adducts exclusively. However, the reaction could not be extended to esters and acyl chlorides. Other metals such as cadmium and tin could also be used to mediate gem-difluoroallylation. The regiochemistry of this reaction could be rationalized in terms of the more nucleophilic α-carbon of the gem-difluoroallyl intermediate
TL;DR: O-Silylated ketene acetals undergo 1,4 conjugate addition to hindered α,β-unsaturated carbonyl systems at atmospheric pressure in the presence of lithium perchlorate as mentioned in this paper.
TL;DR: A 16-step synthesis of (±)-14-deoxisoamijiol is reported in this article featuring an intramolecular addition of an allylsilane to a conjugated dienone to construct stereospecifically the dolastane skeleton.
Abstract: A 16-step synthesis of (±)-14-deoxisoamijiol is reported featuring an intramolecular addition of an allylsilane to a conjugated dienone to construct stereospecifically the dolastane skeleton
TL;DR: In this article, a careful reinvestigation was carried out on the reaction of chalcone (1,3-diphenyl-2-propne-1-one) with malononitrile.
TL;DR: Aldol and Michael as mentioned in this paper added fluorinated nitroalkanes to aldehydes, ketones, esters, and α,β-unsaturated carbonyl derivatives.
Abstract: Aldol and Michael Additions of Fluorinated Nitroalkanes to Aldehydes, Ketones, and α,β-Unsaturated Carbonyl Compounds1,2)
2,2,2-Trifluoronitroethane (1) and 3,3,3-trifluoro-2-nitropropane (2), despite their great propensity to undergo HF elimination with base, can be added to aldehydes with KF or neutral alumina (nitroaldol products 7–15). With basic alumina (neat components) they even add to α,β-unsaturated aldehydes, ketones, esters, and nitriles (γ-nitro carbonyl derivatives and nitrile 27–35). Doubly lithiated difluoro and trifluoro nitro derivatives (H, L) can be generated from the corresponding nitroethanes and -propanes (1–3) with butyllithium (THF, — 100 to −70°C) and added to aldehydes and ketones to give nitroaldols (nitroethanols 11, 12, 16–21) and “homonitroaldols” (nitropropanols 36–38). In essentially all cases, mixtures of diastereoisomers are formed. Through O-silyltrifluoronitroaldols (22–26) it is possible to enrich one of the diastereoisomers by 3:1 (Scheme 4). Some transformations of the nitro compounds obtained lead to CF3-substituted aminoethanols (39–46, by catalytic hydrogenation on Raney nickel), a nitrobutanol (30 48, with Et3SiH), and a ketone (30 49, with Bu3SnH).
TL;DR: A stereocontrolled synthesis of (±)-pumiliotoxin C from 4methoxypyridine in seven steps was reported in this paper, where the synthesis was carried out in the same year.
TL;DR: The Michael additions of activated nitriles to methyl acrylate (MA) and methyl vinyl ketone (MVK) proceeds with fair to high yields (46–92%) in the presence of catalytic amount of HRh(CO)(PPh3)3 1 under mild eaction conditions.
TL;DR: Cyanohydrin diethyl phosphates, readily obtained from various ketones and aldehydes, react chemoselectively with samarium(II) iodide in THF to give the corresponding nitriles in excellent yields as mentioned in this paper.
Abstract: Cyanohydrin diethyl phosphates, readily obtained from various ketones and aldehydes by reaction with diethyl phosphorocyanidate and lithium cyanide, reacted chemoselectively with samarium(II) iodide in THF to give the corresponding nitriles in excellent yields. This method was also found applicable to α,β-unsaturated carbonyl compounds via cyano phosphates to give β,γ-unsaturated nitriles, not obtainable by standard methods, without isomerization of the double bonds
TL;DR: The Michael reaction of several β-dicarbonyl compounds, such as methyl vinyl ketone, acrolein and methyl acrylate as acceptors, was carried out in this paper without any solvent.
TL;DR: In the presence of a catalytic amount of bismuth(III) trichloride (5 mol%), silyl enol ethers react with aldehydes at room temperature in dichloromethane to give the corresponding aldols in good yields.
Abstract: In the presence of a catalytic amount of bismuth(III) trichloride (5 mol%), silyl enol ethers react with aldehydes at room temperature in dichloromethane to give the corresponding aldols in good yields. Silyl enol ethers also have been found to react with α,β-unsaturated ketones at room temperature in dichloromethane to afford the corresponding 1,5-dicarbonyl compounds, the Michael adducts in good yields. The intermediate adducts of the aldol reaction (the silyl ethers) and the Michael reaction (the silyl enol ethers) were also obtained in good yields.