反应详情

To a suspension of 6,6-dimethyl-morpholine-3-carboxylic acid (Intermediate 19, 540 mg) in 17 ml of ethanol (under nitrogen) was added 100 mg of 10% Pd on charcoal and 830 ul (3 eq.) of 37% aqueous formaldehyde. The mixture was purged with hydrogen (balloon) and stirred at ambient temperature for 5 hrs. To the resulting gray mixture were added 4 ml of water and 4 ml of methanol to help dissolution. The catalyst was removed by filtration and the filtrate was concentrated to dryness. The residue was triturated with EtOAc. The generated white solid was filtered off and dried under high vacuum to give 574 mg of 4,6,6-trimethyl-morpholine-3-carboxylic acid (97% yield).

1. customThe mixture was purged with hydrogen (balloon)
2. additionTo the resulting gray mixture were added 4 ml of water and 4 ml of methanol
3. dissolutiondissolution
4. customThe catalyst was removed by filtration
5. concentrationthe filtrate was concentrated to dryness
6. customThe residue was triturated with EtOAc
7. filtrationThe generated white solid was filtered off
8. customdried under high vacuum