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5th August 2013 @ 02:29
Coupling of Boc-protected glycine and 4-aminoantipyrine using T3P. Repeat of PMY 29-2. AEW63-1 ([blog=7555]Resynthesis of tert-butyl (2-((1,5-dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)amino)-2-oxoethyl)carbamate, OSM-S-17 (AEW 63-1)[/blog]) didn't proceed as well as Paul Ylioja's reaction. Procedure:Boc-Gly-OH (500 mg, 2.85 mmol, 1 equiv.) and 4-aminoantipyrine (638 mg, 3.14 mmol, 1.1 equiv.) were dissolved in DMF (2.5 mL) and pyridine (1.30 mL, 16.14 mmol, 5.65 equiv.). The mixture was cooled in an ice/bath and T3P (50 wt.% in EtOAc, 3.1 mL, 4.9 mmol, 1.7 equiv.) was added. The mixture was allowed to warm to room temperature and the mixture stirred overnight. No SM present. Water (30 mL) was added and the mixture stirred for 20 minutes. 10% NaHCO3 was added until pH 8 and then the mixture was extracted with EtOAc, water, brine then dried (MgSO4) and concentrated under reduced pressure to give a yellow/white solid (555 mg, ~1.54 mmol, ~54% yield), used directly in next step. Data: TLC (10% MeOH/DCM): [data]7236[/data] Mini-work up:Drop of reaction mixture quenched with water and partitioned with EtOAc. Potential for SM to have remained in aqueous. NMR: [data]7244[/data][data]7246[/data] Risk and Hazard Assessment:As for, [blog]1170[/blog] See also:[blog]1400[/blog][blog]1346[/blog][blog]1296[/blog][blog]1270[/blog] InChI=1S/C18H24N4O4/c1-12-15(20-14(23)11-19-17(25)26-18(2,3)4)16(24)22(21(12)5)13-9-7-6-8-10-13/h6-10H,11H2,1-5H3,(H,19,25)(H,20,23)
Attached Files
AEW 72-1.jpg
AEW 72-1 crude NMR.pdf