Showing papers on "Enone published in 1980"
TL;DR: An efficient organocopper conjugate addition based on the use of equimolar amounts of an enone and an entering group is described in this article, where the enone is added to the conjugates.
43 citations
38 citations
TL;DR: Asymmetric coordination of prochiral 1,3-dienes to form optically active (diene)Fe(CO)3 complexes has been achieved by direct transfer of the Fe(CO)-3 group from chiral enone complexes as mentioned in this paper.
33 citations
TL;DR: Photocycloadditions of 3-butylcyclopent-2-en-one to alkenes and alkenyl acetates in potassium dodecanoate micelles give [2 + 2] cycloadducts: the regioselectivity of the addition is different from that obtained in homogeneous solution in organic solvents.
Abstract: Photocycloadditions of 3-butylcyclopent-2-en-one to alkenes and alkenyl acetates in potassium dodecanoate micelles give [2 + 2] cycloadducts: the regioselectivity of the addition is different from that obtained in homogeneous solution in organic solvents.
24 citations
TL;DR: Anhydrous lithium iodide in ether, tetrahydrofuran, or benzene is an effective reagent for the formation of αβ-unsaturated ketones by condensation of alkyl ketones with enolisable and non-enolisable aldehydes as mentioned in this paper.
Abstract: Anhydrous lithium iodide in ether, tetrahydrofuran, or benzene is an effective reagent for the formation of αβ-unsaturated ketones by condensation of alkyl ketones with enolisable and non-enolisable aldehydes; in the presence of trimethylchlorosilane–triethylamine enone formation is suppressed and high yields of 1,3-hydroxy-ketones are obtained as their trimethylsilyl ether derivatives
21 citations
TL;DR: Robinson annelation of thujone with methyl and ethyl vinyl ketones proceeds stereospecifically to afford the tricyclic enones 6 and 4 respectively as discussed by the authors.
Abstract: Robinson annelation of thujone (1) with methyl and ethyl vinyl ketones proceeds stereospecifically to afford the tricyclic enones 6 and 4 respectively. Enone 4 was converted to the glycol 13 which ...
12 citations
TL;DR: In this article, the synthesis of 11-deoxy-8, 10-diazaprostaglandin E1 (1a) starting from methyl 3-benzyloxycarbonyl-2-oxo-4-imidazolidinecarboxylate (3a) is reported.
Abstract: The synthesis of 11-deoxy-8, 10-diazaprostaglandin E1 (1a) starting from methyl 3-benzyloxycarbonyl-2-oxo-4-imidazolidinecarboxylate (3a) is reported. Alkylation of 3a with methyl 7-bromoheptanoate and NaH gave methyl 1-benzyloxycarbonyl-3-(6-methoxycarbonyl) hexyl-2-oxo-4-imidazolidinecarboxylate (9), which was converted into the 4-hydroxymethyl-imidazolidine derivative (10). The Moffatt oxidation of 10, and the Wittig reaction of the resulting aldehyde (11) with dimethyl 2-oxoheptylphosphonate provided an enone (12). Reduction of 12, and hydrolysis of a mixture of C15-epimeric alcohols (15) followed by re-esterification afforded 11-deoxy-8, 10-diazaprostaglandin E1 methyl ester (17a). Alkaline hydrolysis of 17a gave 1a as crystals in a good yield. The 10-methyl derivative (2a) was also synthesized. Methylation of 3a with methyl iodide and K2CO3 gave the 1-methylimidazolidine analog (7a), which was converted into methyl 3-(6-methoxycarbonyl) hexyl-1-methyl-2-oxo-4-imidazolidinecarboxylate (20) after debenzyloxycarbonylation and alkylation with methyl 7-bromoheptanoate. Conversion of 20 into 2a was carried out by a synthetic sequence similar to that used for the elaboration of 1a.
11 citations
TL;DR: In this article, it was shown that 2-methyl-5-phenylfuran gives cis-1,4,2-dioxazolylbutenones (5), the structures of which have been confirmed by the synthesis of the dihydro-derivative from the reaction of benzonitrile oxide with hexane-2,5-dione.
Abstract: Oxidation of hydroxamic acids at room temperature in the presence of 2,5-dimethylfuran gives cis-1,4,2-dioxazolylbutenones (5), the structures of which have been confirmed by the synthesis of the dihydro-derivative (12) from the reaction of benzonitrile oxide with hexane-2,5-dione. If the oxidation is carried out at 0 °C good yields of the unstable furo[1,4,2]dioxazines (7), the formal products of the addition of the furan to the nitrosocarbonyl-arene or -alkane, can be isolated. Compounds (7) are the precursors to (5) and this isomerisation in the oxidation medium is essentially quantitative. It is probably catalysed by an unidentified component, since when pre-isolated (7) is heated the reaction is solvent-dependent and sometimes complex, the amounts of (5) formed being very variable. Nitrosocarbonylbenzene adds to the unsymmetrical compound 2-methyl-5-phenylfuran only at the 2,3-bond, giving the dioxazine (17) and thence the dioxazole (15) exclusively. Secondary amines add readily to the β-carbon of the enone group in (5) while tertiary amines, or more efficiently iodine, convert (5) into the trans-isomers (11)The retro-reaction of (5c) at 80 °C to dimethylfuran and p-nitronitrosocarbonylbenzene has been demonstrated by trapping the latter, with 1,4-dimethyl-2,3-diphenylcyclopentadiene, as the adduct (21).
11 citations
10 citations
TL;DR: The photo-induced alkylation of enone 6 with ethylene glycol gave an adduct from which the α-D-threo (16) and α- D-erythro (17) modifications of structure 2 have been elaborated.
Abstract: The photo-induced alkylation of enone 6 with ethylene glycol gave an adduct from which the α-D-threo (16) and α-D-erythro (17) modifications of structure 2 have been elaborated. It was thereby show...
10 citations
TL;DR: This article described a new sequence of old reactions to make desired enones that doesn't appear in the recent compilations of synthetic methods, which involves the Reformatsky condensation of propargyl bromide with a ketone or aldehyde, followed by an acid catalyzed rearrangement to the enone.
TL;DR: In this paper, the isomerization of methano-methano-α-enones was shown to be a singulet process, and the tripartite reaction was found to be triplet.
Abstract: Photochemistry of γ,δ-Methano-α-enones
Direct excitation (λ = 254 or ≥ 347 nm) converts the γ,δ-methano-α-enone (E)-10 into the isomeric ether 23 and the isomeric diene-ketone 24. Furthermore, on 1π,π*-excitation (λ = 254 nm) (E)-10 undergoes an 1,3-homosigmatropic rearrangement yielding the enone (E)-25. In addition (E Z)-isomerization of (E)-10 and conversion of 10 to the isomeric furan 28 is observed.
The isomerization (E)-10 23, 24 and (E)-25 proceeds by photocleavage of the C(γ), C(δ)-bond, whereas the formation of 28 occurs by photocleavage the C(γ), C(δ)-bond together with that of the C(γ), C(δ′)-bond of 10.
On direct excitation the bicyclic diene-ether 23 yields the methano-enone 10, the dieneketone 24 and the tricyclic ether 29. Evidence is given, that the conversion 23 10 is a singulet process. On the other hand, the isomerization 23 24 and the intramolecular [2 + 2]-photocycloaddition 23 29 are shown to be triplet reactions.
Irradiation (λ = 254 nm) of the homoconjugated ketone 24 yields the isomeric ketone 27 by an 1,3-acyl shift. The excitation of the (E)-enone 25 induces (E Z)-isomerization and photoenolization to give the homoconjugated ketone 26.
TL;DR: In this paper, the behavior of metallated imines and hydrazones toward α,β-unsaturated ketones was studied, using different reaction times and temperatures, and the functional group (imine or hydrazone) in the adducts and regioselectivity in their condensation reactions were discussed.
TL;DR: In this article, the synthesis of sugar derivatives bearing a spiro Heterocycle via nucleophilic cyclization was studied and the reaction was stereospecific leading to the isomer bearing the N-atom on the endo face of the bicyclic starting material.
Abstract: Synthesis of Sugar Derivatives Bearing a Spiro Heterocycle via Nucleophilic Cyclization
Treated with the 1,4-binucleophiles 1,2-diaminoethane, 2-aminoethanol, 2-aminoethanethiol, L-cysteine, o-phenylenediamine, o-aminophenol or o-aminothiophenol the ketosugar derivative 1 gave in good yields the corresponding spiro derivatives 2–8. In each case, the reaction was stereospecific leading to the isomer bearing the N-atom on the endo face of the bicyclic starting material. Starting from the sugar enone 9, the aromatic 1,4-binucleophiles led stereospecifically to the spirobenzo [b]-diazepine 10, -oxazepine 11 or -thiazepine 12. In one case, an imine (13) was isolated. As 13 cyclized to 6, the intermediate formation of these kind of derivatives could be considered as a common step for all these reactions.
TL;DR: In this paper, the influence of diene structure and enone substituent on the dissociative pathway of the Fe(CO)4 (PhCHCH2) intermediate is discussed.
Abstract: Exchange of various mono-olefins with styrene in [Fe(CO)4(PhCHCH2)] proceeds via a dissociative process, involving an Fe(CO)4 intermediate. Ligand exchange in system (i)(enone = benzylideneacetone, cinnamaldehyde, chalcone, or dypnone; polyene = cyclohexa- and cyclohepta-1,3-diene, cycloheptatriene, cycle-octatetraene, [Fe(CO)3(η4-enone)]+ polyene ⇌[Fe(CO)3(η4-polyene)]+ enone (i) or 1,4-diphenylbuta-1,3-diene) is stepwise, involving a rate-determining dechelation of the π-bound CO moiety. Both associative and dissociative pathways are found. The influence of diene structure and enone substituent is discussed.
TL;DR: In this article, the crystal and molecular structure of the methylester 1b has been determined by X-ray analysis, and the lattice parameters are a = b = 9.848 A and c = 35.955 A: the space group is P4 1 2 1 2.
TL;DR: Three 3-sulphonylcyclohex-2-enones have been prepared as potential C−H analogues of carboxylic acid dimers, the molecules being designed to associate as doubly bridged hydrogen-bonded dimers via their alkene C-H groups as discussed by the authors.
Abstract: Three 3-sulphonylcyclohex-2-enones have been prepared as potential C–H analogues of carboxylic acid dimers, the molecules being designed to associate as doubly bridged hydrogen-bonded dimers via their alkene C–H groups. 1H N.m.r. and i.r. spectra show no evidence of such an association. The crystal and molecular structure of the title compound has been determined from X-ray diffraction data by direct methods and refined to R 0.034 for 2 008 independent reflections. The crystals are monoclinic, a= 10.243(1), b= 8.755(2), c= 11.672(2)A, β= 102.94(1)°(at 153 K), space group P21/c, and Z= 4. Although the molecules associate as dimers, the H ⋯ O distance (2.63 A) is too long to be described as a hydrogen bond. The association probably arises from dipole–dipole attractions between the polarised C–H groups and the carbonyl oxygen atoms of the two molecules.
TL;DR: The decarboxylation of various 1-substituted-3, 7-dioxabicyclo[3.3.0] octane-2, 8-diones (2b-j) was in vestigated.
Abstract: The decarboxylation of various 1-substituted-3, 7-dioxabicyclo[3.3.0]octane-2, 8-diones (2b-j) was in vestigated. On treatment with potassium acetate in aqueous pyridine under reflux, all the compounds (2b-j) examined were decarboxylated in high yields to give the corresponding trans-3-hydroxymethyl-4-butanolides (3b-j). The synthesis of 10-oxa-11-deoxyprostaglandin E2 (1a) from the compounds 3i and 3j is also described. The Moffatt oxidation of 3i and the Wittig reaction of the resulting aldehyde (6a) with dimethyl 2-oxoheptylphosphonate gave an enone (7a), which was converted into 10-oxa-11-deoxyprostaglandin E2 methyl ester (8a) and the C15-epimer (9a) by NaBH4 reduction. Hydrolysis and subsequent relactonization of 8a gave 1a in 88% yield. A similar treatment of 9a gave 1b in 87% yield. Using a similar sequence of reactions, 1a and 1b were also prepared from the nitrile analog 3j via 8b and 9b.
TL;DR: In this article, it was shown that strict stereo-electronic requirements are necessary for enone ring closure and that these conditions are not met in base-catalysed 5-Endo- and 6-endo-trigonal ring closures of the phenols of general type.
Abstract: The phenolic enones (4), (5), (8), (9), and (13) cyclise readily under acidic conditions. However, neither these nor the thin-substituted phenols (11a), (13a), (14a), and (15a) closed under basic conditions. Involvement of unfavourable equilibria is disproved. Comparison is made with related successful cyclisations of the saturated ketone (38) and aldehyde (39). Preliminary results suggest that strict stereo-electronic requirements are necessary for enone ring closure and that these conditions are not met in base-catalysed 5-Endo- and 6-Endo-Trigonal ring closures of the phenols of general type (2; n= 0 and n= 1).
TL;DR: In this paper, the synthesis of 11-deoxy-8, 10-diazaprostaglandin E1 (1a) starting from methyl 3-benzyloxycarbonyl-2-oxo-4-imidazolidinecarboxylate (3a) is reported.
Abstract: The synthesis of 11-deoxy-8, 10-diazaprostaglandin E1 (1a) starting from methyl 3-benzyloxycarbonyl-2-oxo-4-imidazolidinecarboxylate (3a) is reported. Alkylation of 3a with methyl 7-bromoheptanoate and NaH gave methyl 1-benzyloxycarbonyl-3-(6-methoxycarbonyl) hexyl-2-oxo-4-imidazolidinecarboxylate (9), which was converted into the 4-hydroxymethyl-imidazolidine derivative (10). The Moffatt oxidation of 10, and the Wittig reaction of the resulting aldehyde (11) with dimethyl 2-oxoheptylphosphonate provided an enone (12). Reduction of 12, and hydrolysis of a mixture of C15-epimeric alcohols (15) followed by re-esterification afforded 11-deoxy-8, 10-diazaprostaglandin E1 methyl ester (17a). Alkaline hydrolysis of 17a gave 1a as crystals in a good yield. The 10-methyl derivative (2a) was also synthesized. Methylation of 3a with methyl iodide and K2CO3 gave the 1-methylimidazolidine analog (7a), which was converted into methyl 3-(6-methoxycarbonyl) hexyl-1-methyl-2-oxo-4-imidazolidinecarboxylate (20) after debenzyloxycarbonylation and alkylation with methyl 7-bromoheptanoate. Conversion of 20 into 2a was carried out by a synthetic sequence similar to that used for the elaboration of 1a.
TL;DR: The decarboxylation of various 1-substituted-3, 7-dioxabicyclo[3.3.0] octane-2, 8-diones (2b-j) was in vestigated as mentioned in this paper.
Abstract: The decarboxylation of various 1-substituted-3, 7-dioxabicyclo[3.3.0]octane-2, 8-diones (2b-j) was in vestigated. On treatment with potassium acetate in aqueous pyridine under reflux, all the compounds (2b-j) examined were decarboxylated in high yields to give the corresponding trans-3-hydroxymethyl-4-butanolides (3b-j). The synthesis of 10-oxa-11-deoxyprostaglandin E2 (1a) from the compounds 3i and 3j is also described. The Moffatt oxidation of 3i and the Wittig reaction of the resulting aldehyde (6a) with dimethyl 2-oxoheptylphosphonate gave an enone (7a), which was converted into 10-oxa-11-deoxyprostaglandin E2 methyl ester (8a) and the C15-epimer (9a) by NaBH4 reduction. Hydrolysis and subsequent relactonization of 8a gave 1a in 88% yield. A similar treatment of 9a gave 1b in 87% yield. Using a similar sequence of reactions, 1a and 1b were also prepared from the nitrile analog 3j via 8b and 9b.
TL;DR: In this article, the ring opening reactions of acetoxydifluorocyclopropanes with various nucleophiles were investigated and shown to yield α-fluoro-β-methoxy ketone.
Abstract: Ring opening reactions of acetoxydifluorocyclopropanes with various nucleophiles were investigated. Alkaline hydrolysis of acetoxydifluorocyclopropane afforded the α, α-difluoro ketone, α-fluoro enone and, in the case of 4, α-fluoro-β-methoxy ketone (8), while reactions with CH3Li, Grignard reagent and LiAlH4 gave the corresponding fluoro allyl alcohol derivatives (15) exclusively, in good yields. The reaction of 3 with CH3MgI in the presence of CuBr afforded 2-fluoro-3-methylcyclotridecanone (21).
Patent•
08 Jan 1980
TL;DR: A process for the preparation of compounds of the general formula I: wherein R represents hydrogen or a protecting group, which comprises selective reduction of a compound of the generic formula II, wherein R is as defined above, and Hal represents halogen; with optional total or partial inversion of the hydroxyl or protected hydroxym substituent; and, when R is a protecting groups, optional removal of the protecting group from the compound of general formula 1.
Abstract: A process for the preparation of compounds of the general formula I: wherein R represents hydrogen or a protecting group, which comprises selective reduction of a compound of the general formula II: wherein R is as defined above, and Hal represents halogen; with optional total or partial inversion of the hydroxyl or protected hydroxyl substituent; and, when R is a protecting group, optional removal of the protecting group from the compound of general formula 1