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16th June 2010 @ 06:39
Preparation of starting material for the [url=http://www.thesynapticleap.org/node/317]Ugi reaction[/url] – [url=http://www.ourexperiment.org/racemic_pzq/309]upscaling of reaction [b]MW34-1[/b][/url] [data=size:500x180]196[/data] [data=size:500x150]198[/data] Start time: 10:45 AM 16/06/2010 End time: 9:50 AM 17/06/2010 To a mixture of phenethylamine (5.00 g, 41.3 mmol), benzyltriethylammonium chloride (TEBACl) (470 mg, 2.06 µmol, 5 mol%) and NaOH (3.30 g, 61.9 mmol, 2 eq.) in CH2Cl2 (30 mL) was added chloroform (7.39 g, 5.0 mL, 61.9 mmol, 1.5 eq.) and heated to reflux. - after 12 h the solution was cooled to room temperature and stirred vigorously for another 12 h. TLC (hexane:EA, 4:1, stain: KMnO4): some remaining starting material Work-up: quenched with water, extracted with DCM, washed with 1 N aq. HCl-solution, dried over magnesium sulfate, concentrated. - dark brown oil, crude yield: 3.32 g - purification by column chromatography (silica gel, hexane/EA, 6:1, stain: KMnO4), Rf = 0.28 [b]Result:[/b] Product [b]MW34-2[/b]: 1.72 g (13.1 mmol, 32%) brown liquid; yield reference: 60% [1] -> not engough NaOH? - 2 equivalents used instead of 4 eq. in the previous trial
Attached Files
Reaction Scheme1
Table1