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18th October 2011 @ 02:47
=== Repeat of [url=]PMY 15-1[/url]: Reduction of pyrrole-3-ester [url=]PMY 6-1[/url] using [url=]LiAlH4[/url]. [b]Reaction start time: 08.50 18/10/11[/b] [url=]LiAlH4[/url] (72 mg, 1.91 mmol, 1 equiv, 4 hydride equiv.) was stirred in Et2O (5 mL) at room temperature (water bath). [url=]PMY 6-1[/url] (500 mg, 1.91 mmol, 1 equiv.) in Et2O (10 mL) was added dropwise over 5 minutes. After 6 hours, a saturated solution of [url=]Rochelle's salt[/url] (approx 10 mL) was added, shaken and left to separate. Diluted with EtOAc (30 mL). Separated and aqueous extracted with EtOAc (3 × 20 mL), dried (MgSO4) and concentrated under reduced pressure. The residue was then purified by chromatography (2-30% EtOAc/hexane) to obtain an off-white solid (264 mg, 63%). [i]Emulsion did not break fully, potentially cause of poor yield. Also suspect product is slightly unstable on silica, requires 2D TLC to check. Undeveloped TLC spots turn blue over time.[/i] 25/10/11 Sample has turned very dark with some purple precipitate over the weekend. Sample was stored in the dark at room temperature. 19F NMR shows mostly new product. 1H shows 2 peaks at 4.53 and 4.40 compared to 4.50 on original sample. TLC shows 3 spots. [b]TLC (25% EtOAc/hexane) visualised with UV and vanillin:[/b] [data]550[/data] [b]NMR:[/b] [data]586[/data] [data]600[/data] [b]Risk and Hazard Assessment:[/b] See:[blog]704[/blog] See also: [blog]403[/blog] InChI=1S/C13H14FNO/c1-9-7-11(8-16)10(2)15(9)13-5-3-12(14)4-6-13/h3-7,16H,8H2,1-2H3
Attached Files
TLC 5 hours
1H, 19F, 13C NMR
1H, 19F NMR after 3 days