4 h. The bomb was then vented and solvent was evaporated. The

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four h. The bomb was then vented and solvent was evaporated. The crude item was passed through a quick silica plug applying 10 30 EtOAc/hexanes as the eluent. The enantiomeric ratio was then measured through chiral GC evaluation. Methyl (S)-4-Hydroxy-3-methylbutanoate (three) Colorless oil, 15.2 g (95 isolated yield); 1H NMR (400 MHz, CDCl3) four.05 (s, 3H), three.35 (dd, J = six.6, 12 Hz, 2H), two.48 (m, 2H), 2.07 (m, 1H), 0.92 (d, J = 6.six Hz, 3H); 13C NMR (one hundred MHz, CDCl3) 171.0, 68.5, 62,1, 37.eight, 32.5, 14.7. HRMS (ESI, TOF): m/z = 133.0864, calcd For C6H13O3 [M+H]+ 133.0865.Preparation of (S)-4-Methyldihydrofuran-2(3H)-one (four)To a answer of methyl (S)-4-hydroxy-3-methylbutanoate (12 g, 90 mmol) in 30 mL of CH2Cl2, TsOH (0.95 equiv) was added at space temperature. The mixture was stirred for 6 h, then the organic layer was washed with H2O (three 30 mL), brine and dried more than Na2SO4. Solvent was removed under decreased pressure to yield solution as colorless oil (9.eight g, 98 ).J Org Chem. Author manuscript; available in PMC 2014 December 06.Khumsubdee et al.PageProcedure for Recrystallization(S)-4-Methyldihydrofuran-2(3H)-one 4 was dissolved in EtOAc and hexane and the mixture was cooled to -20 . After obtaining precipitation, solvent was decanted in low temperature and washed with cold hexane.NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author ManuscriptPreparation of Methyl (S)-4-((tert-Butyldiphenylsilyl)oxy)-3-methylbutanoate (five)To a resolution of methyl (S)-4-hydroxy-3-methylbutanoate 3 (5.5 g, 42 mmol) in 30 mL of DMF, TBDPSCl (0.95 equiv) was added at area temperature. The mixture was stirred for 4 h, then solvent was removed beneath reduced stress. The residue was dissolved in CH2Cl2. The organic layer was washed with H2O (3 30 mL), brine and dried over Na2SO4. Solvent was removed under reduced stress along with the crude was purified by chromatography making use of 5 EtOAc/hexane as eluent to acquire item five as a clear oil (15 g, 99 ). 1H NMR (400 MHz, CDCl3) 7.79 7.30 (m, 10H), 3.69 (s, 3H), 3.59 (dd, J = three.three, 12 Hz, 2H), two.63-2.60 (m, 2H), 2.32-2.20 (m, 1H), 1.09 (s, 9H), 1.02 (d, J = 6.6 Hz, 3H); 13C NMR (one hundred MHz, CDCl3) 173.5, 137.eight, 133.eight, 129.7, 126.9, 68.7, 51.9, 38.7, 26.eight, 19.7, 16.1. HRMS (ESI, TOF): m/z = 371.0222, calcd for C22H31O3Si [M+H]+ 371.0242.Preparation of (S)-4-(tert-Butyldiphenylsilyloxy)-3-methylbutanal (six)A modification of reported procedure20 was applied.Fraxetin Epigenetics Below an atmosphere of argon, to an oven dried flask was added [Ir(COD)Cl]2 (10.Lasalocid Technical Information 1 mg, 0.PMID:23910527 015 mmol) and 1.5 mL of CH2Cl2. Then diethyl silane (529 mg, six.0 mmol) was added plus the resulting mixture was stirred at 23 for 1 minute. Following addition of methyl (S)-4-((tert-butyldiphenylsilyl)oxy)-3methylbutanoate 5 (three.0 mmol), the mixture was stirred at 23 for 1 h. Then add one more portion of [Ir(COD)Cl]2 (10.1 mg, 0.015 mmol) and diethyl silane (265 mg, 3.0 mmol) for the mixture and let it to stir 23 for two h. The reaction was diluted with diethyl ether and quenched by 0.1 M HCl. Following stirring for 20 minutes, the layers have been separated along with the aqueous layer was extracted with CH2Cl2. The combined organic layers have been dried with MgSO4, and concentrated below vacuum. Purification on the residue by flash chromatography on silica gel, eluting with 10 15 CH2Cl2/hexanes gave the preferred aldehyde 6 as colorless oil (766 mg, 75 ). 1H NMR (400 MHz, CDCl3) 9.86 (t, J = 2.1 Hz, 1H), 7.81 7.74 (m, 4H), 7.54 7.47 (m, 6H), three.70 (dd, J = 9.9, five.1 Hz, 1H), 3.57 (dd, J = 9.9, six.9 Hz,.