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17th February 2011 @ 08:19
Attempts to the acid-mediated cyclization of the [url=http://www.ourexperiment.org/racemic_pzq/1555]N-benzoyl-protected Ugi intermediate [b]MW51-1[/b][/url] with methanesulfonic acid See also: [*] [url=http://www.ourexperiment.org/racemic_pzq/464]Attempts to the Bronstedt-acid catalysed Pictet-Spengler cyclization using BINOL-N-triflyl phosphoramide (MW41)[/url] [*] [url=http://www.ourexperiment.org/racemic_pzq/470]Cleavage of the dimethoxy acetal of 2-((2,2-dimethoxyethyl)amino)-N-phenethylacetamide hydrochloride MW7(MW42)[/url] [data=size:500x150]797[/data] [b]Hazard and Risk Assessment:[/b] [data]799[/data] [b]MW53-1:[/b] Start time: 7:30 PM 17/02/2011 End time: 10:10 PM 21/02/2011 [url=http://www.ourexperiment.org/racemic_pzq/1555][b]MW51-1[/b][/url] (31 mg, 83.8 µmol, M.W. 370.4 g/mol) was stirred with methanesulfonic acid (0.5 mL) for 15 h at room temperature. - work-up: neutralized with Na2CO3, extracted with DCM, dried with Na2SO4, evaporated [data=text]809[/data] [b]MW53-2:[/b] Start time: 7:30 PM 17/02/2011 End time: 9:30 PM 21/02/2011 [url=http://www.ourexperiment.org/racemic_pzq/1555][b]MW51-1[/b][/url] (29 mg, 78.4 µmol, M.W. 370.4 g/mol) was stirred with formic acid (0.5 mL) for 4 days at room temperature. - work-up: neutralized with Na2CO3, extracted with DCM, dried with Na2SO4, evaporated [data=text]811[/data] [b]MW53-3:[/b] Start time: 7:15 PM 21/02/2011 End time: 9:30 PM 22/02/2011 [url=http://www.ourexperiment.org/racemic_pzq/1555][b]MW51-1[/b][/url] (31 mg, 83.8 µmol, M.W. 370.4 g/mol) was stirred with methanesulfonic acid (0.5 mL) for 14 h at 60°C. - work-up: neutralized with Na2CO3, extracted with DCM, dried with Na2SO4, evaporated TLC: Rf=0.43 (ethyl acetate, 100%, stain ceric ammonium molybdate)- no starting material [data=text]819[/data]: no specific signals because of rotamers [u]TLC:[/u] (Rf=0.43; ethyl acetate, 100%, stain: potassium permanganate), same Rf for starting material and product, product stains without heating. - Stain: ceric ammonium molybdate: product doesn't stain. [data]945[/data] [b]Results:[/b] MW53-1: still starting material, + side products. (after 12 h - no product visible) MW53-2: colourful reaction, no visible starting material, lots of side product (after 2 d - product and a lot of side product) MW53-3: look like a clean reaction (product - almost clean reaction) [b]References:[/b] [url=http://dx.doi.org/10.1021/jo102058s][1] Polycyclic Compounds by Ugi−Pictet−Spengler Sequence, W. Wang†, S. Ollio†, E. Herdtweck and A. Doemling, J. Org. Chem. 2011, 76 (2), pp 637–644. (DOI: 10.1021/jo102058s)[/url]
Attached Files
Reaction Scheme
HRAF MW53.pdf
1H NMR MW53-1.pdf
1H NMR MW53-2.pdf
1H NMR MW53-3.pdf
TLC MW53.JPG