- Diastereoselective photocycloaddition reactions of 2-naphthalenecarboxylates and 2,3-naphthalenedicarboxylates with furans governed by chiral auxiliaries and hydrogen bonding interactions
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By using chiral auxiliaries and hydrogen bonding interactions, we have developed diastereoselective photocycloaddition of 2-naphthalenecarboxylates and 2,3-naphthalenedicarboxylates with furan derivatives. In photoreactions of (?)-menthyl 2-naphthalenecarboxylate with furan and 3-furanmethanol, respective maximum 48% and 40% diastereomeric excesses (d.e.) are observed. In photoreactions of di-8-phenyl-(?)-menthyl 2,3-naphthalenedicarboxylate with 3-furanmethanol, maximum 67% d.e. is obtained. Use of solvents of low polarity, low temperatures and low furan concentration leads to increased diastereoselectivities. Variable-temperature (VT) NMR and fluorescence quenching studies indicate that hydrogen bonding interactions between the carbonyl oxygen of naphthalenecarboxylic acid esters and the OH group in 3-furanmethanol take place in both the ground and excited states. The results of computational studies show that geometries of C2 symmetric naphthalenedicarboxylate reactants are important in governing the high diastereoselectivity in the photoreactions of 2,3-naphthalenedicarboxylates.
- Maeda, Hajime,Koshio, Norihiro,Tachibana, Yuko,Chiyonobu, Kazuhiko,Konishi, Gen-ichi,Mizuno, Kazuhiko
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- METHOD FOR PRODUCING ORGANIC COMPOUND
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PROBLEM TO BE SOLVED: To provide a method of subjecting a compound having on one carbon atom a carbon atom constituting a carbon-carbon double bond and a functional group such as a hydroxyl group to a reductive reaction condition and producing an organic compound having the functional group substituted with a hydrogen atom. SOLUTION: There is provided a method for producing a compound represented by a formula (50) from a raw material compound represented by a formula (10). The method includes a step of irradiating a reaction system with light, the reaction system comprising the raw material compound, a hydrogen source compound, and a catalyst having a palladium component supported by a carrier containing titanium oxide. (R11 to R15 are a hydrogen atom, a hydrocarbon group having 1 to 40 carbon atoms which may have a cyclic structure or a derivative group thereof, or a heteroatom-containing group having 1 to 20 carbon atoms which may have a cyclic structure or a derivative group thereof; and R16 is a hydrogen atom, a hydrocarbon group having 1 to 40 carbon atoms or an acyl group having 1 to 20 carbon atoms which may have a cyclic structure, or -CH(CH2OH)2).) COPYRIGHT: (C)2015,JPO&INPIT
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Paragraph 0084-0087; 0097; 0129; 0134-0135; 0138
(2018/10/16)
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- Cycloaddition of C-3 substituted furans. Stereoselectivity induced by coordination effects
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Several C-3 substituted furans with chelating groups have been reacted with 2,3-dibromo-3-pentanone in the presence of a reducing metal, resulting in the formation of [4+3]-cycloadducts with complete cis-trans and endo-exo diastereoselectivity and in excellent yield. A certain variability of the conversion and reaction yield could be observed, when changing the reaction conditions, but in all cases the stereoselectivity was complete, compared to that of C-3 substituted furans with non-chelating groups. Also, a general method of assignment of stereochemistry of cycloadducts has been established by NMR, considering diagnostic patterns of signals with different multiplicity and chemical shifts depending on the stereochemistry of diastereomeric cycloadducts.
- Montana, Angel M.,Castellvi, Maria,Batalla, Consuelo,Grima, Pedro M.,Font-Bardia, Merce
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p. 9982 - 9998,17
(2012/12/12)
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- Cycloaddition of C-3 substituted furans. Stereoselectivity induced by coordination effects
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Several C-3 substituted furans with chelating groups have been reacted with 2,3-dibromo-3-pentanone in the presence of a reducing metal, resulting in the formation of [4+3]-cycloadducts with complete cis-trans and endo-exo diastereoselectivity and in excellent yield. A certain variability of the conversion and reaction yield could be observed, when changing the reaction conditions, but in all cases the stereoselectivity was complete, compared to that of C-3 substituted furans with non-chelating groups. Also, a general method of assignment of stereochemistry of cycloadducts has been established by NMR, considering diagnostic patterns of signals with different multiplicity and chemical shifts depending on the stereochemistry of diastereomeric cycloadducts.
- Monta?a, ángel M.,Grima, Pedro M.,Castellví, María,Batalla, Consuelo,Font-Bardia, Mercè
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p. 9982 - 9998
(2013/01/14)
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- Cyclization of 2-alkynylallyl alcohols to highly substituted furans by gold(I)-carbene complexes
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Various 2-alkynylallyl alcohols were synthesized by a generally applicable Sonogashira coupling protocol. Subsequent gold-catalyzed transformation was investigated. The use of AuI catalysts bearing carbene ligands, of either the N-heterocyclic carbene or nitrogen acyclic carbene type, delivered the desired products with low catalyst loadings and under very mild reaction conditions. A broad array of substrates was tested, including alkyl-, alkenyl-, and aryl-substituted alkynes, as well as substrates with two alkynyl moieties. The methodology turned out to have a broad scope. Secondary allyl alcohols were also tolerated, and the resulting trisubstituted furans could be isolated in high yields. Easily accessible 2-alkynylallyl alcohols were transformed into highly substituted furans under very mild reaction conditions by the use of gold(I)-carbene catalysts. A broad range of substrates could be transformed in high yields and within short reaction times.
- Hashmi, A. Stephen K.,Rudolph, Matthias,Rominger, Frank
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scheme or table
p. 667 - 671
(2011/03/22)
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- Enantioselective synthesis of (S)- and (R)-fluoxetine hydrochloride
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The enantioselective synthesis of fluoxetine hydrochloride, a potent serotonin-uptake inhibitor, is described. The synthesis of (S)-fluoxetine hydrochloride begins with the asymmetric carbonyl-ene reaction of benzaldehyde with 3-methylene-2,3-dihydrofuran (1) catalyzed by Ti[OCH(CH3)2]4/(S)-BINOL to give (S)-2-(3-furyl)-1-phenyl-1-ethanol (2) in 90% yield and 95% ee. In five steps, alcohol 2 was converted into (S)-fluoxetine hydrochloride (97% ee and 56% overall yield from benzaldehyde). (R)-fluoxetine hydrochloride was prepared by the same sequence except that Ti[OCH(CH3)2]4/(R)-BINOL was used in the first reaction to give the enantiomer of 2.
- Miles, William H,Fialcowitz, Elizabeth J,Scott Halstead
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p. 9925 - 9929
(2007/10/03)
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- Product distributions from the OH radical-induced oxidation of but-1-ene, methyl-substituted but-1-enes and isoprene in NO(x)-free air
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Product distributions resulting from the OH-induced oxidation of but-1-ene, 2-methylbut-1-ene, 3-methylbut-1-ene and isoprene in air were measured in the absence of nitrogen oxides and compared with predictions based on currently accepted oxidation mechanisms. In the case of butenes, the observed distributions of carbonyl compounds, hydroxyketones, hydroxyalkanals and diols were evaluated to obtain probabilities for the initial attack of OH radical on the outer position of the double bond (y = 0.90 ± 0.03 for 2-Me-but-1-ene and y = 0.76 ± 0.05 for both but-1-ene and 3-Me-but-1-ene), for the probability of formation of stable products in the self-reaction of secondary β-hydroxyperoxyl radicals (k(ssb)/k(ss) = 0.29 ± 0.07 for but-1-ene and k(ssb)/k(ss) = 0.19 ± 0.06 for 3-Me-but-1-ene), and for the ratio of the reaction with oxygen vs. decomposition of β-hydroxyalkoxyl radicals, k3[O2]/(k4 + k3[O2]) = 0.25 ± 0.04 for but-1-ene and = 0.38 ± 0.04 for 3-Me-but-1-ene. The last two values disagree with other published data, which suggest a smaller effect of oxygen. The oxidation of isoprene produced methacrolein and methyl vinyl ketone with a ratio 0.93 ± 0.10, the ratio of methyl vinyl ketone and 3-methylfuran was 7.3 ± 1.0. Other products were 1-hydroxy-3-methylbut-3-en-2-one (identified by mass spectrometry) and 3-methyl-3-oxo-butane (tentatively identified). The overall product distribution was complex and could not be fully elucidated. Computer simulations based on several mechanisms applied the relative probabilities for OH addition found for the but-1-enes. Comparison with the experimental data suggests probabilities for OH addition to the methylated double bond of 0.504 ± 0.027 (outer position) and 0.056 ± 0.003 (inner position), and to the non-methylated double bond of 0.335 ± 0.023 (outer position) and 0.105 ± 0.008 (inner position).
- Benkelberg,Boge,Seuwen,Warneck
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p. 4029 - 4039
(2007/10/03)
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- Gas-phase reaction of NO3 radicals with isoprene: A kinetic and mechanistic study
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The gas-phase reaction of NO3 radicals with isoprene was investigated under flow conditions at 298 K in the pressure range 6.8 3 radicals toward isoprene was determined to be (6.86 ± 2.60) × 10-13 cm3 molecule-1 s-1. The formation of the possible oxiranes, 2-methyl-2-vinyl-oxirane and 2-(1-methyl-vinyl)-oxirane, was observed in dependence on total pressure. In the presence of O2 in the carrier gas, the product distribution was found to be strongly dependent on the reaction pathways of formed peroxy radicals, If the peroxy radicals mainly reacted in a self-reaction, the formation of organic nitrates was detected and 4-nitroxy-3-methyl-but-2-enal was identified as a main product. On the other hand, when NO was added to the gas mixture and the peroxy radicals were converted via RO2 + NO → RO + NO2, the formation of methyl vinyl ketone as the main product as well as 3-methylfuran and methacrolein was observed. From the ratio of the product yields if NO was added to the gas mixture it was concluded that the attack of NO3 radicals predominantly takes place in the 1-position. A reaction mechanism is proposed and the application of these results to the troposphere are discussed.
- Berndt, Torsten,Boege, Olaf
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p. 755 - 765
(2007/10/03)
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- Synthesis and ene reactions of 3-methylene-2,3-dihydrofuran
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The unexpected formation of 3-methylene-2,3-dihydrofuran 1 using the Huang-Minlon modification of the Wolff-Kishner reduction of 3-furaldehyde is described. Furan 1 readily undergoes ene reactions with simple electron-deficient alkenes.
- Miles,Berreth,Smiley
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p. 5221 - 5222
(2007/10/02)
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- NMR Studies of Bond Orders in Heteroaromatic Systems
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Fifty-seven for the ortho-benzylic coupling constant 4JMe-C=C-H (henceforth denoted as 4JOB) were obtained for a variety of heteroaromatic systems.It was shown that a good correlation exists between 4JOB when the methyl group is not α to the heteroatom and the SCF-MO bond order.This method can therefore be used as experimental means of determining bond orders in heteroaromatic systems.An examination of bond alternation in thirteen heteroaromatic systems has given a measure of relative "degree of aromaticity" for a larger number of systems than previously r eported by any single method.
- Hatton, Paul M.,Sternhell, Sever
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p. 935 - 946
(2007/10/02)
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- PHOTOCHEMISTRY OF 3,6-DIHYDRO-1,2-OXAZINES: A VERSATILE ROUTE TO SUBSTITUTED PYRROLES
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A high yield pyrrole synthesis which employs a sequence of cycloaddition, photoextrusion of H2O and Birch reduction has been developed.
- Givens, R. S.,Choo, D. J.,Merchant, S. N.,Stitt, R. P.,Matuszewski, B.
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p. 1327 - 1330
(2007/10/02)
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- Gas-Phase Heteroaromatic Substitution. 3. Electrophilic Methylation of Furan and Thiophene by CH3XCH3+ (X = F or Cl) Ions
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A previous radiolytic study on the gas-phase methylation of pyrrole and N-methylpyrrole by CH3XCH3+ (X = F or Cl) ions, from the γ radiolysis of CH3X, is extended to furan (3) and thiophene (4).The mechanism of the susbstitution and of the subsequent isomerization occuring via intramolecular 1,2 methyl-group shift is discussed and the substrate and positional selectivity of the selected electrophilic species evaluated.As for pyrroles, gas-phase CH3FCH3+ methylation of furan and thiophene is characterized by a scarce substrate discrimination (kS/kB = 1.2 (3), 0.8 (4), accompanied by an apprreciable positional selectivity toward those substrate positions with the highest negative net charge (O:α:β = 36percent:35percent:29percent for 3; S:α:β = 19percent:43percent:38percent for 4).On the contrary, CH3ClCH3+ confirm its inherent affinity toward n-type nucleophilic centers by attacking preferently the heteroatom of 3 and 4.In light of the previous results concerning CH3XCH3+ methylation of pyrroles, it is concluded that gas-phase attack of CH3XCH3+ on simple five-membered heteroaromatics is essentially regulated by the electrostatic interaction established within the encounter pair.A close correspondence does exist between this rationalization of the present gas-phase results and recent theoretical predictions.
- Angelini, Giancarlo,Lilla, Gaetano,Speranza, Maurizio
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p. 7091 - 7098
(2007/10/02)
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- Etude des transformations catalytiques sur alumine de β-tetrahydrofurylmethanols
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The products obtained by treatment of β-tetrahydrofurylmethanols at 310-330 deg C, using alumina as catalyst are studied.The nature of the products-furans, tetrahydrofurans, aliphatic and cyclic dienes-shows that beside the simple dehydration side reactions take place leading, as the case may be, to dehydrogenation, raduction, ring opening and fragmentation.
- Infarnet, Yves,Accary, Armand,Huet, Jean
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p. 261 - 266
(2007/10/02)
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