[O:1]1[CH:5]=[CH:4][CH:3]=[C:2]1[CH:6]([CH2:12][CH2:13][CH2:14][CH3:15])[O:7][CH2:8][C:9]([OH:11])=[O:10].[N+](=[CH2:18])=[N-].CN(N=O)C(N[N+]([O-])=O)=N.[OH-].[K+]>CCOCC>[O:1]1[CH:5]=[CH:4][CH:3]=[C:2]1[CH:6]([CH2:12][CH2:13][CH2:14][CH3:15])[O:7][CH2:8][C:9]([O:11][CH3:18])=[O:10]Crude acid from example 84 (25 g, 118 mmol) was dissolved in ether and treated with excess diazomethane (generated by adding 1-methyl-3-nitro-1-nitrosoguanidine (MNNG) to a mixture of 40% KOH (aq) and ether at 0° C.). Excess diazomethane was quenched with acetic acid after 30 m. Vacuum distillation gave 18.8 g (70%): [α]25D -100°; bp 100°-109° C. (0.5 mmHg); 1H NMR (300 MHz, CDCl3) δ7.40 (1H, dd, J=1 Hz), 6.34 (1H, dd, J=1 Hz), 6.29 (1H, dd, J=1 Hz), 4.43 (1H, t, J=7 Hz), 4.00 (2H, q, J=16 Hz), 3.72 (3H, s), 1.92 (2H, m), 1.33 (4H, m), 0.89 (3H, t, J=7 Hz); mass spectrum (FAB): 244 (M+NH4).
Wird geladen…
