- Preparation method of high-purity alpha-pyranone
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The invention discloses a preparation method of high-purity alpha-pyranone. The method is characterized in that a reaction of vinyl acetate and paraformaldehyde is carried out; sodium acetate is addedto the reaction solution, concentration is carried out after stirring, a solvent is removed, then a target product is extracted, and a compound I crude product is obtained; the compound I crude product is distilled under reduced pressure to obtain the compound I; a reaction of the compound I and N-bromosuccinimide is carried out; vacuum filtration is carried out after cooling to room temperature,a filter cake is discarded, and a filtrate is concentrated to obtain a red black liquid, namely a compound II; under water bath conditions, the compound II is added to toluene, triethylamine is addeddropwise, and a reaction is further carried out; the reaction is carried out by heating in the water bath, cooling to room temperature is performed after the reaction is completed, vacuum filtrationis carried out, a filter cake is discarded, and a filtrate is concentrated to obtain a target product crude product; and the target product crude product is subjected to distillation under reduced pressure to obtain the high-purity alpha-pyranone. The GC purity of the high-purity alpha-pyranone prepared by the method can be up to 99% or more, and a total yield is 75% or more.
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Paragraph 0027-0028; 0034-0042; 0048-0055
(2019/11/21)
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- Preparation method of furanone
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The invention discloses a preparation method of furanone. The preparation method includes the steps that an acetone aldehyde solution is prepared, a 3,4-dihydroxy-2,5-hexanedione solution is prepared,3,4-dihydroxy-2,5-hexanedione is purified, semi-finished furanone is prepared, and finished furanone is prepared. The preparation method has the advantages that 1, the yield of the intermediate 3,4-dihydroxy-2,5-hexanedione and the total yield of the furanone can be increased through composite catalyst zinc powder, iron powder and manganese powder, 2, purity of the intermediate 3,4-dihydroxy-2,5-hexanedione is obviously increased by adding anhydrous sodium sulphate and sodium chloride composite powder, and 3, purity of the furanone can be obviously improved by combining extractant ethanol andethyl acetate.
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Paragraph 00178; 0020-0022; 0025-0027; 0030-0031
(2019/11/12)
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- Method for the preparation of (+)-calanolide A and analogues thereof
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A method of preparing (+)-calanolide A, 1, a potent HIV reverse transcriptase inhibitor, from chromene 4 is provided. According to the disclosed method, chromene 4 intermediate was subjected to a chlorotitanium-mediated aldol reaction with acetaldehyde to selectively produce (±)-8a. Separation and enzyme-mediated resolution of (±)-8a produced (+)-8a. Cyclization of (+)-8a under neutral Mitsunobu conditions followed by Luche reduction of (+)-7 produced (+)-calanolide A in high yield and enantiomeric purity. The method of the invention has been extended to produce potent antiviral calanolide A analogues.
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- Ultraviolet and Polarized Infrared Spectroscopy of Matrix-Isolated Cyclobutadiene and Its Isotopomers
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The UV and polarized IR spectra of argon matrix isolated cyclobutadiene and its 1-d-, 1,2-d2-, 1,4-d2-, 1-13C-, 1,2-13C2-, and 1,4-13C2- labeled derivatives are reported.Above 250 nm, the UV spectrum contains no peaks with an extinction coefficient larger than 10 L M-1 cm-1, but a weak absorption tail extends throughout the UV region.The absorption rises abruptly below 250 nm.The IR peak positions mostly agree with previous reports where these are available.Photoalignment studies support the symmetry assignment of fundamental vibrations and prove that the two Kekule forms interconvert rapidly even at 10 K.The spectral and photochemical effe ts of the presence of an adjacent CO2 molecule in the cyclobutadiene matrix site are elucidated.Its presence causes a substantial retardation of the photofragmentation of cyclobutadiene into two acetylenes.This is attributed to accelerated vibrational energy loss from the cyclobutadiene absorber.
- Arnold, Bradley R.,Michl, Josef
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p. 13348 - 13354
(2007/10/02)
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- NITROGEN-CONTAINING SPIROCYCLES
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Spirocycles of general structural formula: STR1 are Class III antiarrhythmic agents.
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- Compounds active as inhibitors of the cholesterol biosynthesis
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The compounds of formula wherein R, R1, R2, R3, and R4 have the meanings given in the specification, are described. The compounds of formula I are active as inhibitors of the enzyme HMG-CoA reductase and can be used in therapy as anti-hypercholesterolemics.
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- BEAZIMIDAZOLE COMPOUNDS ACTIVE AS INHIBITORS OF THE CHOLESTEROL BIOSYNTHESIS
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The compounds of formula wherein R, R1, R2, R3, and R4 have the meanings given in the specification, are described. The compounds of formula I are active as inhibitors of the enzyme HMG-CoA reductase and can be used in therapy as anti-hypercholesterolemics.
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- A GENERAL APPROACH TO THE SYNTHESIS OF 5,6-DIHYDRO-2(2H)PYRANONES; SIMPLE SYNTHESIS OF α-PYRONE, (+/-)-ARGENTILACTONE AND (+/-)-GONIOTHALAMIN
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Easily accessible dihydropyrans undergo oxidation with PDC/t-BuOOH to yield the corresponding 5,6-dihydro-2-(2H)-pyranones in good yield.The methodology is exemplified with the synthesis of α-pyrone, (+/-)-argentilactone and (+/-)-goniothalamin.
- Chidambaram, N.,Satyanarayana, K.,Chandrasekaran, S.
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p. 2429 - 2432
(2007/10/02)
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- The Photo-isomerization of Cyclopentadienone O-Oxide Isolated in Low Temperature Matrices
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Discrepancies in recent reports from different laboratories on the i.r. spectrum of matrix-isolated cyclopentadienone O-oxide have now been reconciled by showing that two distinct isomers may be formed from cyclopentadienylidene and O2, and that one, a carbonyl oxide, may be converted photolytically into the other, a dioxirane.
- Dunkin, Ian R.,Shields, Charles J.
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p. 154 - 156
(2007/10/02)
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- Small Rings, 54. Cyclopentadienone
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Cyclopentadienone (1) can be generated by photolysis or pyrolysis of several precursors and isolated in an argon matrix.It dimerizes even on thawing of the matrix (38 K).The IR and UV spectroscopic properties of 1 are discussed.
- Maier, Guenther,Franz, Lothar Hermann,Hartan, Hans-Georg,Lanz, Klaus,Reisenauer, Hans Peter
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p. 3196 - 3204
(2007/10/02)
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- AN ORGANOMETALLIC ROUTE TO (+/-)-3-p-TOLUENESULFINYL-2-PYRONE
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3-Bromo-2-pyrone reacts with dimethylcopperlithium and then with p-tolyl p-toluenethiosulfonate to form 3-p-toluenethio-2-pyrone.Organocopper species are likely intermediates in this reaction.Oxidation of the sulfide produces (+/-)-3-p-toluenesulfinyl-2-pyrone.The overall process involves an important and useful umpolung, a reversal of reactivity at C(3) of the pyrone ring from an electrophilic center to a nucleophilic center.
- Posner, Gary H.,Harrison, Wayne
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p. C27 - C30
(2007/10/02)
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- NEUE WEGE ZUM CYCLOBUTADIEN UND METHYLENCYCLOPROPEN
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New routes to cyclobutadiene (2) and methylenecyclopropene (4) are described.Matrix irradiation of cyclopropenylketene (9) gives cyclobutadiene.Flash pyrolysis of 8, 11, 16, 17 and 18 also generates cyclobutadiene, which can be deposited from the gas phase onto a window cooled to 10 K.Methylenecyclopropene is one of he products in the thermal fragmentation of 8 or 14.
- Maier, Guenther,Hoppe, Manfred,Lanz, Klaus,Reisenauer, Hans Peter
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p. 5645 - 5648
(2007/10/02)
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- Propanolamine derivatives
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Propanolamine derivatives of the formula: STR1 wherein R2 is CH3 SO or CH3 SO2 ; R3 is hydrogen, methyl or methoxy; or R2 and R3 are together --S(O)m (CH2)4 --when S is attached at R2 or --(CH2)n S(O)m -- when S is attached at R3 (where m=1 or 2 and n=3 or 4); R4 is hydrogen or alkyl C1-4 ; Z is --(CH2)2 -- or STR2 and their non-toxic salts. Processes for the preparation and pharmaceutical compositions thereof. The compounds exhibit both β-adrenoreceptor antagonist activity and vasodilator activity and are indicated for use in the treatment of hypertension.
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- Cyclopentadienone O-Oxide: A Highly Labile Intermediate in the Matrix Reaction between Cyclopentadienylidene and Oxygen
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Cyclopentadienylidene reacts with oxygen in low-temperature matrices, giving a photolabile intermediate, the i.r. spectrum of which suggests that it is the carbonyl oxide, cyclopentadienone O-oxide.
- Bell, Gordon A.,Dunkin, Ian R.
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p. 1213 - 1215
(2007/10/02)
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