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Phosphorus Ylides (phosphorus + ylide)
Selected AbstractsHighly Regioselective Wittig Reactions of Cyclic Ketones with a Stabilized Phosphorus Ylide under Controlled Microwave Heating.CHEMINFORM, Issue 36 2004Jinlong Wu Abstract For Abstract see ChemInform Abstract in Full Text. [source] Chemistry of phosphorus ylides 21 new route for the synthesis of azetidinones.HETEROATOM CHEMISTRY, Issue 6 2005Reaction of phosphonium ylides with benzil-, o -naphthoquinone-, triketonemonoanils Active vinylidenetriphenylphosphoranes are nucleophilic reagents which can be con- sidered as versatile synthons for the synthesis of new heterocycles. The active phosphacumulene ylides, namely N -phenylimino- 2a, 2-oxo- 2b or 2-thioxo-vinylidenetriphenylphosphoranes (2c), react with benzil- (1a,b), o -naphthoquinone- (8), or triketone-monoanils (11), to give the corresponding phenylimino- (3a, d, 9a, 12a), oxo- (3b, e, 9b, 12b), or thioxoazetidinones (3c, f, 9c, 12c), respectively, which constitute an important class of organic compounds with medicinal and biological importance. On the other hand, quinone monoanils 1a, 8, 11 can be converted by reaction with the stabilized alkylidenephosphoranes (5a,d), namely acetylmethylene- 5a, methoxycarbonylmethylene- 5b, ethoxycarbonylmethylene- 5c, and benzoylmethylene-triphenylphosphorane 5d, into the phosphoranylidenes (7a,d, 10a,d, 13a,d). No reaction was observed between iminophosphorane (14) and the monoanil (11). The structures of the new products were assigned according to consistent analytical and spectroscopic data. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:476,483, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20144 [source] Kinetic and mechanistic study on the thermal reactivity of stabilized phosphorus ylides, part 3: [(Acetyl)(arylcarbamoyl)methylene]triphenylphosphoranes and [(alkoxycarbonyl)(arylcarbamoyl)methylene]triphenylphosphoranes and their thiocarbamoyl analoguesINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 1 2007R. Alan Aitken A series of five [(acetyl)(arylcarbabmoyl)methylene]triphenyl-phosphoranes 1a,e and their thiocarbamoyl analogues 2a,e, [(alkoxycarbonyl)(arylcarbamoyl)methylene]triphenylphosphoranes 3a,e and their thiocarbamoyl analogues 4a,e were prepared and fully characterized. All ylides are found under conditions of flash vacuum pyrolysis to fragment giving arylisocyanate or isothiocyanate and acetyl ylides or alkoxy ylides which undergo thermal extrusion of Ph3PO. A kinetic study shows that these reactions are unimolecular and are of first-order nature with no significant substituent effect. The thiocarbamoyl ylides 2 react from 4.6 to 42 times faster than their carbamoyl ylides 1, while the thiocarbamoyl ylides 4 react from 6.6 to 20.9 times faster than their carbamoyl ylides 3. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 39: 6,16, 2007 [source] Synthesis, thermal reactivity, and kinetics of stabilized phosphorus ylides, part 2: [(Arylcarbamoyl)(cyano)methylene]triphenylphosphoranes and their thiocarbamoyl analoguesINTERNATIONAL JOURNAL OF CHEMICAL KINETICS, Issue 8 2006R. Alan Aitken A series of five cyano(arylcarbamoyl) phosphorus ylides 2 and five cyano(arylthiocarbamoyl) phosphorus ylides 3 are prepared and fully characterized. Pyrolytic reaction products of a representative example of each type obtained by flash vacuum pyrolysis technique show that they undergo thermal extrusion of Ph3PO or Ph3PS. Kinetic study of the gas-phase pyrolysis of each ylide by static method shows that these reactions are unimolecular and first order with no significant substituent effect, but the thiocarbamoyl ylides 3 react 40,65 times more rapidly than their carbamoyl analogues 2. © 2006 Wiley Periodicals, Inc. Int J Chem Kinet 38: 496,502, 2006 [source] Synthesis of 5-substituted uracils and 2,4-dimethoxypyrimidines by wittig olefinationJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 6 2005Evdoxia Coutouli-Argyropoulou A variety of new 5-alkenyluracils has been prepared in high yields by Wittig olefination of 5-formyl-1-octy-luracil, 5-formyl-1,3-dioctyluracil and 5-formyl-2,4-dimethoxy pyrimidine with stabilized and semistabi-lized phosphorus ylides. The conformation of the products is discussed on the basis of 1H NMR spectral data. [source] Thermal transformation of arylamidoximes in the presence of phosphorus ylides.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 4 20044-oxadiazoles, Unexpected formation of 3-aryl-5-arylamino- The unexpected formation of 3-aryl-5-arylamino-1,2,4-oxadiazoles took place, when arylamidoximes reacted thermally with ethoxycarbonylmethylene(triphenyl)phosphorane. Furoxans, nitriles, ureas were also isolated suggesting aryl cyanide oxides as intermediates. 3-Aryl-5-arylamino-1,2,4-oxadiazoles were formed via an aryl migration from the carbon atom to the nitrogen atom of the amidoxime, and the structure was further proved from the X-ray crystal structure of the N -(4-bromobenzoyl) derivative. [source] | ||||||||||