Br[CH:2]([CH3:4])[CH3:3].[Mg].[CH:6](NC(C)C)([CH3:8])[CH3:7].[CH3:13][N:14]1[CH2:20][CH2:19][CH2:18][CH2:17][CH2:16][C:15]1=[O:21].CC[O:24]CC>>[CH3:13][N:14]1[CH2:20][CH2:19][CH2:18][CH2:17][CH:16]([C:2]2[CH2:4][CH2:8][CH2:6][C:7](=[O:24])[CH:3]=2)[C:15]1=[O:21]2-Bromopropane (12.3 g) was added to suspension of magnesium (2.43 g) in ether (50 ml) at such a rate to maintain gentle reflux and the mixture was stirred 30 minutes after addition was complete. Diisopropylamine (14 ml) was then added dropwise and the mixture stirred until the Gilman test showed negative (about 1 hour). N-methylcaprolactam (12.7 g) was added dropwise (exothermic). After addition of the N-methylcaprolactam, stirring became difficult due to separation of a sticky solid, which however redissolved on addition of THF (50 ml). After the addition was complete the reaction mixture was stirred for 30 minutes then treated dropwise with 3-isopropoxy-2-cyclohexenone (16.4 g) (exothermic) and stirred overnight. The reaction mixture was poured onto 2 N aq HCl (250 ml) and stirred for 30 minutes. Dichloromethane (300 ml) was added and the layers separated. The aqueous layer was extracted with dichloromethane (2×300 ml) and the combined organic phases dried (MgSO4). Removal of the solvents under reduced pressure followed by recrystallisation of the residue from ethyl acetate gave the title compound (13.2 g) identical with the product of Example 3.
Wird geladen…
