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20th August 2013 @ 13:28

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Reaction information

*#Reaction file
reactionscheme_42 .cdx
*Reaction file type CDX
*Procedure A 25 mL Schlenk flask containing 2,5-Dibromobenzoic acid (128 mg, 0.46 mmol), (4-Ethynylphenyl)(methyl)sulfane (150 mg, 1.01 mmol, 2.20 eq.), PdCl2 (8 mg, 46 μmol, 10 mol%), PPh3 (24 mg, 0.09 mmol, 20 mol%), CuI (17 mg, 0.09 mmol, 20 mol%) and DABCO (310 mg, 2.76 mmol, 6.00 eq.) was evacuated and refilled with argon before adding distilled DMF (10 mL). The reaction mixture was then heated to 60 °C; after 2 h it was interrupted because of the presence of at least 4 fluorescent compounds (as monitored by TLC and UV lamp at 365 nm; two of these were probably originating from decomposition on silica, see next). After most of the solvent was evaporated (rotating evaporator at 60 °C) the residue was dissolved in DCM, washed with water (the pH was found to be ~ 5 and was not corrected) and brine and dried over anhydrous MgSO4. Evaporation of the solvent afforded the crude product (226 mg) that was column chromatographed on silica gel using (3/1) hexane/DCM; the eluent composition was gradually changed to (3/1) DCM/hexane during the elution. The main fraction containing product (bright yellow solid, Rf 0.54 in DCM; green fluorescence at 365 nm, UV longwave) and impurities (totally 47 mg) was purified again by Chromatotron (eluent DCM) followed by precipitation from DCM/hexane. The product (19 mg, 46 μmol, yield 10 %) was found to decompose on silica, originating two fluorescent byproducts with Rfs 0.00 (green fluorescence) and 0.43 (cyan fluorescence) in DCM. The purity could only be assessed by 1H NMR analysis.
*Yield (%) 10 %
*Type of Yield Isolated pure product
PhD Thesis - 16Sep2010_final p19.pdf
PhD Thesis - 16Sep2010_final p130-131.pdf
Further information Compound 42: 2,5-bis(2-(4-(Methylthio)phenyl)ethynyl)benzoic acid

For multistep reactions (or their steps):

Overall reaction? False
For overall reaction - links to child reaction steps  
For step in multistep reaction - link to previous reaction step

Reaction 41: Oxidation of 2,5-dibromoacetophenone: 2,5-Dibromobenzoic acid

Reaction 39: Deprotection of trimethyl(2-(4-(methylthio)phenyl)ethynyl)silane: (4-ethynylphenyl)(methyl)sulfane

For step in multistep reaction - link to following reaction step  
Attached Files
PhD Thesis - 16Sep2010_final p130-131.pdf
reactionscheme_42 .cdx
PhD Thesis - 16Sep2010_final p19.pdf