- Microwave assisted intramolecular wittig reaction: A facile method for the synthesis of conjugated acetylenes
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A rapid and efficient synthesis of acetylenic compounds by the microwave assisted intramolecular Wittig reaction of β-oxo-alkylidene-triphenylphosphoranes is reported.
- Rao, V. V. V. N. Rama,Ravikanth,Reddy, G. Venkat,Maitraie,Yadla,Rao, P. Shanthan
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p. 1523 - 1529
(2007/10/03)
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- Zinc promoted facile method for the acylation of ylides at α-carbon
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Stabilised triphenylphosphonium ylides are acylated at the α-carbon with different acyl groups using zinc.
- Meshram,Reddy, Gondi Sudershan,Reddy, M. Muratidhar,Yadav
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p. 4107 - 4110
(2007/10/03)
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- Flash Vacuum Pyrolysis of Stabilised Phosphorus Ylides. Part 2. Two-step Conversion of Acid Chlorides into Acetylenic Esters and Terminal Alkynes
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The known thermal extrusion of Ph3PO from α-acyl-α-ethoxycarbonyl ylides 1 to give acetylenic esters 2 can be accomplished in excellent yield by using flash vacuum (FVP) at 500 deg C.Upon rasing the furnace temperature to 750 deg C, this reaction is accompanied by unexpected loss of the ethoxycarbonyl group to give the terminal alkynes 7 in moderate yield.A mechanism is proposed for this reaction based on isotopic labelling studies.Ten new examples of ylides 1 have been prepared for the first time.
- Aitken, R. Alan,Horsburg, Caroline E. R.,McCreadie, J. Graeme,Seth, Shirley
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p. 1727 - 1732
(2007/10/02)
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- Reaction of Triphenylphosphine Radical Cation with 1,3-Dicarbonyl Compounds: Electrochemical One-Step Preparation of Dioxomethylenetriphenylphosphoranes
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Electrochemical oxidation of Ph3P (1) in MeCN in the presence of 1,3-dicarbonyl compounds, R1COCH2COR2 (3), with HClO4 as the supporting electrolyte resulted in the formation of the phosphonium salts, Ph3P+ -CH(COR1)COR2 ClO4- (4), provided that R1 and/or R2 is a phenyl group.On the other hand, electrolysis in CH2Cl2 with 2,6-lutidinium perchlorate gave the phosphoranes, Ph3P=C(COR1)COR2 (5), directly from 1 and 3 in fair to excellent yields: in this case, R1 or R2 need not necessarily be a phenyl group.Thus, the electrolysis is shown to be a convenient method to prepare 5 in a single step.Plausible processes for the formation of 4 and 5 are proposed, involving the reaction of electrochemically generated Ph3P+. with the enol form of 3 as the keystep.Keywords - triphenylphosphine; 1,3-dicarbonyl compound; dioxomethyltriphenylphosphonium perchlorate; dioxomethylenetriphenylphosphorane; electrochemical oxidation; constant current electrolysis
- Ohmori, Hidenobu,Maeda, Hatsuo,Tamaoka, Mie,Masui, Masaichiro
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p. 613 - 620
(2007/10/02)
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