Nitrogen → 5-Methoxy-1-methylindazole

関与物質

反応条件

反応手順

A solution of 6-methoxy indazole (1t) (5 g, 33.75 mmol; see Tet Lett., 43(15): 2695 (2002)) in DMF (200 mL) was treated with potassium carbonate (6.06 g, 43.87 mmol) at room temperature. After stirring at for 15 minutes, methyl iodide (2.33 mL, 37.12 mmol) was added. The resulting mixture was heated at 110° C. for 18 hours. LC showed minor starting material left. Additional methyl iodide was added (2.33 mL) and stirring continued for an additional 18 hours. LC showed a 2:1 mixture of the N1 to N2 alkylated isomers. The solvent was evaporated in vacuo and the residue taken up in DCM and washed with 1N HCl. The organic layer was filtered through 1PS paper, evaporated in vacuo and purified on the Biotage eluting with 4:3, 3:1 hexane/Et2O. The desired combined fractions (N1 isomer) were evaporated in vacuo to provide the desired product (2t) as a yellow oil (2.57 g; 47%). 1H NMR (400 MHz, CDCl3) 7.38 (d, J=7.8 Hz, 1H), 7.17 (dd, J=7.8, 1.6 Hz, 1H), 7.13 (d, J=1.6 Hz, 1H), 5.19-5.18 (m, 1H), 4.51-4.44 (m, 1H), 4.43-4.36 (m, 1H), 2.53-2.45 (m, 1H), 2.36-2.30 (m, 1H); MS (ESI+) m/z 163 (M+H) detected.

情報源と証拠