反应详情

A mixture of (S)-2-isopropylamino-4-methyl-pentanoic acid (70.86 g, 0.41 mol, Example 19, Step A) and aqueous HCHO (94 mL of 37.2%) was agitated in an atmosphere of hydrogen (pressure, 47-52 psi) at 50° C. in absolute ethanol (1.5 L) in the presence of Pd/C (20%, 5 g) until the absorption of hydrogen almost ceased. The catalyst was removed by filtration. The filtrate was concentrated in vacuo to dryness. One hundred milliliters of water was added and concentrated to dryness, and this operation was repeated twice to remove most of HCHO. Absolute ethanol (100 mL) was then added and concentrated to dryness to remove residual water. The white solid collected was triturated with acetone. Filtration and drying under vacuum gave 69.39 g (89%) of the desired product as a white solid; mp 159-160° C. APCI-MS m/z 188.2 (MH+).

1. customThe catalyst was removed by filtration
2. concentrationThe filtrate was concentrated in vacuo to dryness
3. additionOne hundred milliliters of water was added
4. concentrationconcentrated to dryness
5. customto remove most of HCHO
6. additionAbsolute ethanol (100 mL) was then added
7. concentrationconcentrated to dryness
8. customto remove residual water
9. customThe white solid collected
10. customwas triturated with acetone
11. filtrationFiltration
12. customdrying under vacuum