- Carbene-catalyzed LUMO activation of alkyne esters for access to functional pyridines
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A carbene-catalyzed LUMO activation of α,β-unsaturated alkyne esters is reported. This catalytic process allows for effective reactions of alkyne esters with enamides to synthesize functional pyridines via simple protocols. A previously unexplored unsaturated alkyne acyl azolium intermediate is involved in the key step of the reaction.
- Mou, Chengli,Wu, Jichang,Huang, Zhijian,Sun, Jun,Jin, Zhichao,Chi, Yonggui Robin
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p. 13359 - 13362
(2017/12/26)
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- On the synthesis of arylpropiolic acids and investigations towards the formation of vinyl chlorides by HCl addition during esterification reactions
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The synthesis protocol for the preparation of different arylpropiolic acids using the Negishi reaction and the addition of HCl to the alkyne moiety of these acids in subsequent esterification reactions using SOCl2 was examined. Georg Thieme Verlag Stuttgart New York.
- Hapke, Marko,Kral, Karolin,Spannenberg, Anke
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p. 642 - 652
(2011/04/15)
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- Synthesis of 1,4-diphenylbutadiene derivatives: Novel inducer of tissue-type plasminogen activator (t-PA) in cultured bovine endothelial cells
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(E,E)-1,4-Diphenylbutadiene derivatives were synthesized by utilizing the Stobbe reaction of dimethyl succinate as a key step. Their stereoisomers were also synthesized stereoselectively by means of the cross-coupling reaction of the vinylstannanes and the vinylbromides, which were obtained from the propiolic acid esters by stereoselective hydrostannation, as a key step. To discover novel stimulators of fibrinolysis in vascular endothelial cells, the synthesized compounds were added to cultured bovine endothelial cells to determine the activity of the plasminogen activator in the conditioned medium. Of the synthesized compounds, three compounds were found to stimulate the activity of the plasminogen activator in endothelial cells. In addtition, these compounds inhibited thrombus formation in a rat model of venous thrombosis.
- Sai, Hiroshi,Ogiku, Tsuyoshi,Ohmizu, Hiroshi,Ohtani, Akio
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p. 1686 - 1693
(2007/10/03)
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- Synthesis and antitumour activity of new derivatives of flavone-8-acetic acid (FAA). Part 4: Variation of the basic structure
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A range of 11 derivatives of flavone-8-acetic acid (FAA) in which the structure has been substantially altered in different ways have been prepared and their anti-tumour activity evaluated in vitro against a panel of human and murine tumour cell lines and in vivo against MAC 15A. The generally poor activity observed shows that the basic structure cannot be altered much without destroying the activity.
- Alan Aitken,Bibby, Michael C.,Cooper, Patricia A.,Double, John A.,Laws, Andrea L.,Ritchie, Robert B.,Wilson, David W.J.
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p. 181 - 188
(2007/10/03)
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- Flash Vacuum Pyrolysis of Stabilised Phosphorous Ylides. Part 4. Stepwise Construction of Terminal 1,3-Diynes, Conjugated Diacetylenic Esters and a Triacetylenic Ester
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Thirteen examples of stabilised alkynol ylides 6 have been prepared and are found, upon flash vacuum pyrolysis (FVP) at 500 deg C, to undergo extrusion of Ph3PO to give the diacetylenic esters 7 in moderate yield.At 750 deg C the same ylides afforded terminal 1,3-diynes 8 although often in poor yield.For R = 2-MeSC6H4 both 7 and 8 undergo secondary loss of Me* and cyclisation to give 2-alkynylbenzothiophene derivatives 9 and 10 in low yield.The first example of an alkadiynol ylide 11 has been prepared and is converted by FVP at 500 deg C into the triacetylenic ester 12.
- Aitken, R. Alan,Seth, Shirley
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p. 2461 - 2466
(2007/10/02)
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- Preparation of Arylpropiolate Esters from Trichlorocyclopropenium Cation and Elaboration of the Esters to Unsymmetrical 1,4-Pentadiyn-3-ones and Unsymmetrical Tellurapyranones
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The addition of aromatic compounds including thiophene, naphthalene derivatives, and some benzene derivatives to trichlorocyclopropenium cation gave nearly quantitative yields of 1-aryl-2,3,3-trichlorocyclopropenes.Alcoholysis of the cyclopropene derivatives gave either arylpropiolate esters or arylpropiolate orthoesters (in the presence of added amine base).The arylpropiolates can be converted to unsymmetrical 1,4-pentadiyn-3-ones by two different approaches.The first approach involved reduction of the arylpropiolate esters with diisobutylaluminum hydride to give the corresponding propargyl alcohol.Pyridinium chlorochromate or manganese dioxide oxidation of the alcohol gave the propargyl aldehydes.Addition of a lithium acetylenide gave a 1,4-pentadiyn-3-ol, which could then be oxidized to the 1,4-pentadiyn-3-one with 10percent chromic acid or manganese dioxide.The second pathway used a Lewis acid mediated coupling of a propargylic acid chloride with a (trimethylsilyl)acetylene to give the 1,4-pentadiyn-3-ones directly.The coupling of 2-thiophenepropiolic acid chloride gave the product of HCl addition to the expected 1,4-diynone.The regiochemistry of addition was determined to be chloride addition to the thiophene-bearing triple bond on the basis of 1H NMR studies.The diynones were converted to unsymmetrical 2,6-disubstituted tellura-4H-pyran-4-ones with disodium telluride anion.
- Wadsworth, Donald H.,Geer, Susan M.,Detty, Michael R.
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p. 3662 - 3668
(2007/10/02)
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