Nitrogen → 6,7-dihydro-8(5H)-quinolinone oxime

Participants

Reaction Steps

A solution of 5,6,7,8-tetrahydroquinoline (10.83 g, 81.3 mmol) and lithium diisopropylamide (LDA) (22.80 mL, 163 mmol) in dry MTBE (tert-butyl methyl ether) (100 mL was stirred for 10 min while dry N2 (nitrogen) was purged through the system. The solution was then cooled in an acetone-dry ice bath to between −30° C. and −20° C. A 2.5 M solution of nBuLi (n-butyllithium) in hexanes (101.0 mL, 253 mmol) was then added over a period of 5 min. The temperature of the cooling bath was maintained below −20° C. throughout the addition. The thus obtained orange/red mixture was then transferred via cannula to a pre-cooled solution of isoamyl nitrite (38.40 mL, 285 mmol) in dry MTBE (100 mL) at −30° C.; the transfer took about 10 min. The resulting mixture was stirred at −30° C. for 40 min at which time water (4.80 mL) was added in one portion. The quenched mixture was slowly warmed to ambient temperature. A brown solid precipitated from the crude mixture and was collected via filtration. The solid isolate was redissolved in CH2Cl2 (300 mL) and then filtered to remove any insoluble material. The solvent was removed in vacuo and the residue was recrystallized from 1:1 MTBE-hexanes to provide 10.05 g (75%) of the title compound as a beige solid. 1H NMR (CDCl3) δ 1.87–1.96 (m, 2H), 2.81 (t, 2H, J=6 Hz), 2.93 (t, 2H, J=8 Hz), 7.18 (dd, 1H, J=9, 6 Hz), 7.48 (dd, 1H, J=9, 1 Hz), 8.52 (dd, 1H, J=6, 1 Hz), 9.63 (br s, 1H); 13C NMR (CDCl3) δ 20.8, 23.8, 28.9, 123.4, 134.5, 136.7, 148.2, 148.9, 152.7. ES-MS m/z 163 (M+H).

Provenance & Evidence