Showing papers on "Enone published in 1978"
TL;DR: In the presence of palladium complexes as catalysts, fluorinated disilanes add to 1,3-dienes, metehyl vinyl ketone and p -benzoquinone to give mainly 1,4-addition products as mentioned in this paper.
68 citations
TL;DR: In this paper, a biogenetic-type asymmetric synthesis of optically active galanthamine ((+)-4 and (-)-4) is described, and the synthesis of (-)-galanthamine from L-tyrosine via enantiomeric interconversion of narwedine derivative (12) is also described.
Abstract: A biogenetic-type asymmetric synthesis of optically active galanthamine ((+)-4 and (-)-4) is described. Norbelladine derivative (10), having C2 symmetry in the aromatic moiety of C6-C1-N part, was prepared from L-tyrosine, and was converted to narwedinetype enone (11) by oxidation and highly specific asymmetric cyclization. Phosphorylation of phenolic hydroxyl group followed by sodium borohydride reduction afforded 14 having galanthamine skeleton. N-Methylation followed by removal of the methoxycarbonyl and phosphate moieties afforded (+)-galanthamine ((+)-4). Formal total synthesis of (-)-galanthamine ((-)-4) from L-tyrosine via enantiomeric interconversion of narwedine derivative (12) is also described.
38 citations
35 citations
TL;DR: Silyl-lithium reagents add to the β-position of αβ-unsaturated enones in the presence of copper(I) iodide, and the enone can be regenerated by treatment with copper(II) bromide.
Abstract: Silyl-lithium reagents add to the β-position of αβ-unsaturated enones in the presence of copper(I) iodide, and the enone can be regenerated by treatment with copper(II) bromide.
32 citations
31 citations
TL;DR: In this paper, an AB→ABC approach was used to construct a tricyclic enone 3 for taxodione synthesis, but this approach was flawed by a low yield in the penultimate closure of the C ring.
21 citations
TL;DR: In this article, reaction of phosphononitrile 2 with a series of a-enones in THF- n -BuLi gives different results according to the enone nature.
21 citations
16 citations
TL;DR: In this article, the carboxyl group was removed by photolysis in abs ethanol or with zinc-acetic acid, and the removal of the p -methoxyphenacyl group can be achieved either upon photo-lysis or by zinc acetic acid.
12 citations
TL;DR: In this paper, the authors considered the Robinson annulation of a bicyclic β-ketoester and methyl vinyl ketone to obtain the tricyclic enone, and the major obstacle in such an approach involved the Aldol condensation step in the annulation process in which an enolate at C-11 must condense with a highly substituted carbonyl group at C -9.
11 citations
TL;DR: In this paper, a comparison of dipole moments and the calculation of π-electronic charges on the interacting orbitals of both enone and substrate leads to the conclusion that the regioselectivity of enone-alkyne photoannelation may be controlled by the dipole-dipole interactions between the 3π, π*) state of the Enone and the ground state of substrate.
TL;DR: In this paper, the chemistry of 1,6-dihydro-3(2H)-pyridinones was investigated and the synthesis of ethyl 1,b-dhydro3 (2∼)pyridisinone-l-carboxylate (3∼ R=CO2Et).
TL;DR: In this paper, anhydrous hydrogen fluoride in pyridine (70% solution) at 55° and yielded the corresponding 4-en-4-ols e.g. 4-hydroxy-5-fluoro-5α-4α-ol derivative of the parent enone.
TL;DR: The Michael acceptor 5a is a useful synthon for the two-step synthesis of 2,3-disubstituted pyridines from Δ 2 -pyrrolines as discussed by the authors.
TL;DR: In this paper, a Diels Alder reaction was used to test 2,3,4,4-cyclopent-2-enone (I) as a dienophile for pinguisone.
Patent•
22 Mar 1978
TL;DR: The preparation and use as odorant and/or flavorant of compounds having the formula: "STR1" where R represents a butyl, but-2-enyl or 1,3-butadienyl group as discussed by the authors.
Abstract: The preparation and use as odorant and/or flavorant of compounds having the formula: ##STR1## wherein R represents a butyl, but-2-en-yl or 1,3-butadienyl group.
TL;DR: The 2-methyl ketone (2a, b) as mentioned in this paper is derived from the ketones and can afford the cis-imines and trans-imine by the Leuckart and Bischler-Napieralski reactions.
Abstract: The 2-methyl ketone (2a, b), which are derived from the ketones (1a, b), afford the cis-imines (7a, b) and trans-imines (8a, b) by the Leuckart and Bischler-Napieralski reactions. Their methiodies (9a, b and 10b) are converted into the cis-lactams (15a, b) and trans-lactam (17b) via oxidation of the pseudo cyanides (14a, b and 16b). Bromination and successive dehydrobromination of 2a give the enone (20) which affords the cis-imine (23) and trans-imine (24) by the same procedure as above. The cis-methiodide (25) of 23 is reduced to give the cis-amine (26). The cis-lactams (15a, b) and cis-amine (26) can be connected with the synthetic methods of corynoline analogues, which were already known.
TL;DR: In this paper, the double Michael reaction of 3-methyl, 2,3-dimethyl-, and 3-5dimethyl-4-methylenecyclohex-2-enone with dimethyl 3-oxoglutarate in dimethyl sulphoxide in the presence of potassium fluoride as a catalyst gave stereoselectively 9.
Abstract: Double Michael reaction of 3-methyl-, 2,3-dimethyl-, and 3,5-dimethyl-4-methylenecyclohex-2-enone with dimethyl 3-oxoglutarate in dimethyl sulphoxide in the presence of potassium fluoride as a catalyst gave stereoselectively 9-methyl-, 1,9-dimethyl-, and 4,9-dimethyl-6,8-dimethoxycarbonyl-2,7-dioxo-cis-decalin, respectively.
TL;DR: In this paper, photolysis of 7-syn-isobutylnorborn-2-en-2yl methyl ketone (7) and its deuteriated isomer (8) are described.
Abstract: Preparation and photolysis of 7-syn-isobutylnorborn-2-en-2-yl methyl ketone (7) and its deuteriated isomer (8) are described Irradiation of (7) in its n,π* band (λ > 3 400 A) leads to two volatile isomers (11)(55%) and (13)(10%), whilst (8) gives (11d) and (13d) The same products were obtained on irradiation of (7) and (8) in the π,π* band (λ > 2 500 A), along with two additional ketones, the photoreduction product (16) and the dienone (25) These results indicate that isomerization of (7) occurs through hydrogen abstraction by the β-carbon atom of the enone system, but not the α-carbon atom Thus minimization of stereochemical and geometric differences between α and β carbons relative to the abstractable hydrogen does not suffice to elicit abstraction at both centres The structure of the brexane photoproduct (13) was secured through independent synthesis from olefinic ester (38a) Synthesis of (7), (8), and (13) made use of the novel reaction of a norbornene with trichloroacetyl isocyanate to form an unsaturated nitrile [as (31)→(34) and (38)→(39)]
Patent•
11 Sep 1978TL;DR: In this paper, an improved process for the preparation of 2-(7-hydroxyalkyl)-4R, 4S or 4RS -hydroxy-cyclopent-2enone corresponding to the formula ##STR1## wherein m is an integer from 2 to 4.
Abstract: Disclosed is an improved process for the preparation of 2-(7-hydroxyalkyl)-4R, 4S or 4RS -hydroxy-cyclopent-2-enone corresponding to the formula ##STR1## wherein m is an integer from 2 to 4. The compounds prepared by this process are useful as precursors in the preparation of carbinol PGE 1 analogues having utility as bronchodilators and inhibitors of gastric secretion.
TL;DR: In this paper, the cyclization of N-acrylyl-trans-and-cis-octahydro-7 (1H)-quinolones (IXa and IXb) was examined under both acidic and basic conditions.
Abstract: The cyclization of N-acrylyl-trans-and-cis-octahydro-7 (1H)-quinolones (IXa and IXb) was examined under both acidic and basic conditions. Under kinetic conditions, the trans-isomer (IXa) gave two isomeric tricyclic lactams (X and XI) while the cis-isomer (IXb) gave no cyclized compounds. Under thermodynamic conditions, the cis-isomer (IXb) as well as the trans-isomer (IXa) gave the same lactams (X and XI). In the former case with kinetic conditions, the difference in behavior toward cyclization between IXa and IXb was interpreted by taking a stereoelectronic requirement for the Michael addition into consideration, and in the latter case with thermodynamic ones, unexpected formation of the lactams (X and XI) from the cis-isomer (IXb) was rationalized by assuming a reaction pathway via the intermediate enone (XXII) of which we succeeded in isolation from the reaction mixture.
Patent•
01 Sep 1978TL;DR: In this paper, a large batch of 2,6-dimethyl-2,5-heptadiene-4-one was cyclized without isolation to high yields of 3bromo-2-hydroxy-4,4,5, 5,5 -tetramethylcyclopenta-2enone.
Abstract: Bromination of large batches of 2,6-dimethyl-2,5-heptadiene-4-one below -20° C. followed by dehydrobromination without intermediate isolation and recrystallization to produce 3,5-dibromo-2,6-dimethyl-2,5-heptadiene-4-one which can be cyclized without isolation to high yields of 3-bromo-2-hydroxy-4,4,5,5-tetramethylcyclopenta-2-enone is disclosed.
TL;DR: In this paper, the triplet-state enone on the triple bond is characterized by a constantρ of 1.554, which excludes a concerted mechanism, and the increased enone ring size reduces the rate of reaction in comparison with 2-cyclopentenone.
Abstract: 1.
Photocycloaddition of 1-hexyne to six-membered cyclicα, β-enones involves electrophilic attack of the triplet-state enone on the triple bond; the reaction is characterized by a constantρ of 1.554, which excludes a concerted mechanism.
2.
The increased enone ring size reduces the rate of reaction in comparison with 2-cyclopentenone.
3.
We cannot unequivocally attribute the orientation of the reaction to any one electronic or steric effect of the enone substituent.
TL;DR: In this paper, the cyclization of N-acrylyl-trans-and-cis-octahydro-7 (1H)-quinolones (IXa and IXb) was examined under both acidic and basic conditions.
Abstract: The cyclization of N-acrylyl-trans-and-cis-octahydro-7 (1H)-quinolones (IXa and IXb) was examined under both acidic and basic conditions. Under kinetic conditions, the trans-isomer (IXa) gave two isomeric tricyclic lactams (X and XI) while the cis-isomer (IXb) gave no cyclized compounds. Under thermodynamic conditions, the cis-isomer (IXb) as well as the trans-isomer (IXa) gave the same lactams (X and XI). In the former case with kinetic conditions, the difference in behavior toward cyclization between IXa and IXb was interpreted by taking a stereoelectronic requirement for the Michael addition into consideration, and in the latter case with thermodynamic ones, unexpected formation of the lactams (X and XI) from the cis-isomer (IXb) was rationalized by assuming a reaction pathway via the intermediate enone (XXII) of which we succeeded in isolation from the reaction mixture.
TL;DR: Silyl-lithium reagents add to the β-position of αβ-unsaturated enones in the presence of copper(I) iodide, and the enone can be regenerated by treatment with copper(II) bromide.
Abstract: Silyl-lithium reagents add to the β-position of αβ-unsaturated enones in the presence of copper(I) iodide, and the enone can be regenerated by treatment with copper(II) bromide.