反应详情

To 1.15 g (0.005 mol) of (+)-6-methoxy-α-methyl-2-naphthaleneacetic acid, i.e., naproxen, in 50 ml of ethyl acetate was added 0.53 g (0.005 mol) of N-hydroxypiperidine in 20 ml of ethyl acetate and 1.1 g (0.005 mol) of dicyclohexylcarbodiimide. A suspension formed immediately. After 0.5 hour, the suspension was filtered and the residue of dicyclohexylurea (0.6 g) was discarded. The filtrate was concentrated and that residue was suspended in 200 ml of ether and filtered. The ether filtrate was concentrated and that residue was crystallized from 20 ml of cyclohexane. The crystals from cyclohexane were filtered and identified as the acylurea by-product. The cyclohexane solution was concentrated to 5 ml and diluted with 5 ml of heptane to give 0.84 g (mp 95°-97° C., 54% yield) of the desired acylated hydroxylamine (C). The crude product was recrystallized from heptane to give analytically pure product: TLC (silica gel, ether) Rf 0.51; IR (KBr) 1735 cm-1 (s) (C=O), NMR (CDCl3)δ7.8-7.0 (m, 6, aromatic-H), 3.9 (s, 3, CH3 --O), 3.8 (q, 1, J=7 Hz, CH--CH3), 3.5-2.3 (m, 4, CH2N), 1.57 (d, 3, J=7 Hz, CH3 --CH) and 2.0=0.9 (m, 6, CH2).

1. customA suspension formed immediately
2. filtrationthe suspension was filtered
3. concentrationThe filtrate was concentrated and that residue
4. filtrationfiltered
5. concentrationThe ether filtrate was concentrated and that residue
6. customwas crystallized from 20 ml of cyclohexane
7. filtrationThe crystals from cyclohexane were filtered
8. concentrationThe cyclohexane solution was concentrated to 5 ml
9. additiondiluted with 5 ml of heptane