- Efficient preparation of 2-methyl-1,3-dioxolane-2-ethanol and 2-(2-bromoethyl)-2-methyl-1,3-dioxolane from 4-hydroxy-2-butanone
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2-Methyl-1,3-dioxolane-2-ethanol was prepared in 90% isolated yield from 4-hydroxy-2-butanone and ethylene glycol using a weak acid catalyst and ethyl acetate as the reaction solvent. 2-(2-Bromoethyl)-2-methyl-1,3-dioxolane was prepared in 75% isolated yield by bromination of 2-Methyl-1,3-dioxolane-2-ethanol with dibromotriphenylphosphorane. The reagent was prepared in situ by titrating triphenylphosphine with bromine at an ice-ethanol bath temperature. The target compounds are useful methyl vinyl ketone equivalents.
- Petroski, Richard J.
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- Fragmentation of Acylium Ions from Methyl Levulinate. Isomerization Processes Involving Carbon and Oxygen Atoms of Both Carbonyl Groups
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The fragmentations of the acylium ions O=C+-CH2-CH2-CO2CH3 and O=C+-CH2-CH2-COCH3 generated from methyl levulinate are governed extensively by the interaction of the two carbonyl groups.Both species eliminate a molecule of CO unimolecularly and under CID conditions.The results derived from measurements of 13C and 18O labelled precursors, together with kinetic energy release values, have been used to study the mechanisms.In the first of these acylium ions, both carbonyl groups are equivalent; this phenomenon can be the result of a 1,4 methoxy shift.In the second acylium ion, only the oxygen atoms change their positions; this isomerization occurs via the + ion of γ-valerolactone.Some other fragmentation processes also discussed in relation to 2H labelling are the formation of the + ion and the loss of HCOOCH3 in the collision-induced dissociation mass spectra of the first acylium ion, and the formation of the + ion and the loss of H2O for the second one.
- Corval, M.,Harrata, A.,Morizur, J-P.
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Read Online
- Microwave-assisted synthesis of substituted tetrahydropyrans catalyzed by ZrCl4 and its application in the asymmetric synthesis of exo- and endo-brevicomin
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(Chemical Equation Presented) The ZrCl4-catalyzed deprotection of 1,3-dioxane/dioxalane and the simultaneous formation of 6-methoxy-substituted tetrahydropyrans proceeded under microwave irradiation in good yield. This synthetic methodology was
- Singh, Surendra,Guiry, Patrick J.
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supporting information; experimental part
p. 5758 - 5761
(2009/12/08)
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- Stereoselective Synthesis of 14-Azaestra-17-Thia-1,3,5(10)-Triene
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Racemic 14-aza-8-isoestra-17-thia-1,3,5(10)-triene derivatives are obtained by stereoselective addition of thiirane and methylthiirane at the C=N bond of cis-1,2,4a,5,6,10b-hexahydro-8-methoxy-3-methylbenzo[f]quinoline. Configuration in crystal state of unsubstituted in position 16 compound with cis-fusion of C and D rings established by X-ray structural investigation. Attempt to obtain analogs of the compounds with naturally fused B and C rings failed.
- Sokolov,Salfetnikova,Potekhin
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p. 838 - 846
(2007/10/03)
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- AN IMPROVED SYNTHESIS OF 2-(β-BROMOETHYL)-2-METHYL-1,3-DIOXOLANE, A USEFUL METHYL VINYL KETONE EQUIVALENT
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A general method for the formation of β-bromo-ketals, and its application to an improved synthesis of 2-(β-bromoethyl)-2-methyl-1,3-dioxolane, a useful methyl vinyl ketone equivalent, in 82percent yield, are described.
- Hsung, Richard P.
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p. 1175 - 1179
(2007/10/02)
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- 4-(6'-Methoxy-3',4'-dihydronaphthalen-1'-yl)butan-2-one and the Derived Guareschi Imide
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4-(6'-Methoxy-3',4'-dihydronaphthalen-1'-yl)butan-2-one (6b) was condensed with ethyl cyanoacetate to give a mixture of the geometric isomers of the α,β-unsaturated cyano ester (8), reaction of which with the anion derived from cyanoacetamide gave the Guareschi imide (7).Attempts to hydrolyse this to 3--3-methylglutaric acid (4) gave only polymeric material.The preparations of 2,2-ethylenedioxy-4-(6'-methoxynaphthalen-1'-yl)butane (5a) and the corresponding butanone (5b) are also described.
- Collins, David J.,James, Alison M.
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p. 215 - 221
(2007/10/02)
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- 1,2-1,4 addition reaction sequence leading to disubstituted acelylenes
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A method for synthesizing a tri-substituted phenyl compound (I) by using a 1,2-addition followed by a 1,4-addition to 1,4-benzoquinone (II): STR1 wherein X is hydroxy, alkoxy or alkanoyloxy, Ar1 is an organic group and R is an unsubstituted or
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- A General Approach to the Synthesis of C8-Oxygenated Guaianolides
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Preparation of an advanced intermediate for the synthesis of several highly oxygenated members of the guaianolide family of sesquiterpene lactones is described.The key hydroxy lactone species is constructed from the readily available hydroazulene 3 via th
- Rigby, James H.,Wilson, Jo Ann Zbur
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- TRIMETHYLSILYL-HALIDE-MEDIATED CONJUGATED ADDITION TO ALLYLIC ACETALS
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Trimethylsilyl chloride can effect the conjugated addition of NaX (X=Br, I, SCN) to α,β-unsaturated acetals and ketals without deprotection of the carbonyl group.
- Feringa, Ben L.
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- α Chain dienic prostanoic acid derivatives
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α Diene 16-hydroxy prostanoic acid derivatives displaying valuable pharmacological properties, e.g., gastric antisecretory, are described herein.
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- Jasmonoid Synthesis from cis-4-Heptenoic Acid
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Jesmonoids with cis-2-pentenyl side-chain such as cis-jasmone, methyl jasmonate, and jasmolone were easily synthesized from cis-4-heptenoic acid obtained by the ring opening reaction of β-propiolactone with di-cis-butenylcuprate.
- Sato, Toshio,Kawara, Tatsuo,Sakata, Kazumi,Fujisawa, Tamotsu
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p. 505 - 508
(2007/10/02)
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