1-methoxybutan-2-one

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 2-Methyl-7-(2,4,6-trimethyl-phenyl)-4,5,6,7-tetrahydro-2H-pyrazolo[3,4-b]pyridin-3-ylamine (5-44; 101 mg, 0.373 mmol) was dissolved in CH2Cl2 (2 mL). Et3N (0.25 mL, 1.79 mmol) and the 1-methoxy-butan-2-one (65 mg, 0.636 mmol) were added at room temperature. A solution of TiCl4 in toluene (1 M; 0.35 mL, 0.35 mmol) was added dropwise via syringe. The mixture was then stirred at room temperature overnight. NaCNBH3 (120 mg, 1.9 mmol) in methanol (1 mL) was added slowly. The stirring continued at room temperature for 0.5 h and the reaction was quenched by the addition of 2 N NaOH (2 mL). EtOAc was added and the layers were separated. The organic layer was washed with water, brine and dried over MgSO4. The solvent was removed and the residue purified by chromatography on SiO2 (gradient elution: 2% MeOH in CH2Cl2 containing 0.1% NH4OH to 3% MeOH in CH2Cl2 containing 0.15% NH4OH over 20 minutes) to yield 102 mg of 5-40 (0.286 mmol; 77%). The stirring continued at room temperature for 0.5 h the reaction was quenched by the addition of 2 N NaOH (2 mL) EtOAc was added the layers were separated The organic layer was washed with water, brine dried over MgSO4 The solvent was removed the residue purified by chromatography on SiO2 (gradient elution: 2% MeOH in CH2Cl2 containing 0.1% NH4OH to 3% MeOH in CH2Cl2 containing 0.15% NH4OH over 20 minutes)