Acetic Acid → 1-Methyl-2,3-dihydro-1H-indole

To a solution of the resulting indoline(180 mg, 0.603 mmol) and acetic acid (0.1 mL) in methanol (5 mL), 37% aqueous formaldehyde (0.054 mL, 0.723 mmol) was added dropwise at 0° C. The reaction mixture was stirred at room temperature under nitrogen for 1 h, and then was cooled to 0° C. again. Sodium cyanoborohydride (95 mg, 1.5 mmol) was added in portions at 0 ° C. The mixture was stirred at room temperature under nitrogen for 3 h and then quenched with 2 N NaOH and extracted (3×) with methylene chloride. The combined organic layers were washed with brine, dried over Na2SO4, filtered and concentrated in vacuo. The residue was purified by chromatography (SiO2, EtOAc/methanol, 10:1) to afford the N-methyl indoline product, Example 53 as a white solid (140 mg, 74%): mp 63-65° C.; 1H NMR (300 MHz, CDCl3) δ 7.07-7.20 (m, 4H), 6.59 (d, J=8.0 Hz, 1H), 6.28 (d, J=8.0 Hz, 1H), 4.14(t, J=7.9, 5.0 Hz, 1H), 3.58 (d, J=15.0 Hz, 1H), 3.46 (d, J=15.0 Hz, 1H), 3.33 (t, J=8.2 Hz, 2H), 2.93 (dd, J=11.3, 5.0 Hz, 1H), 2.82 (t, J=8.2 Hz, 2H), 2.72 (s, 3H), 2.54 (dd, J=11.3, 7.9 Hz, 1H), 2.42 (s, 3H); CI MS m/z=313 [C19H2iClN2+H]+; IR (KBr) 2940, 2796, 1611, 1594, 1489, 1372, 1286 cm−1; Anal. Calcd for C19H21ClN2: C, 72.95; H, 6.77; N, 8.95. Found: C, 72.70; H, 6.83; N, 8.78.

1. temperaturewas cooled to 0° C. again
2. stirringThe mixture was stirred at room temperature under nitrogen for 3 h
3. customquenched with 2 N NaOH
4. extractionextracted (3×) with methylene chloride
5. washThe combined organic layers were washed with brine
6. dry with materialdried over Na2SO4
7. filtrationfiltered
8. concentrationconcentrated in vacuo
9. customThe residue was purified by chromatography (SiO2, EtOAc/methanol, 10:1)

ORD record

ord-81bfe9d130b04b9b973e875432af5744

Source dataset

uspto-grants-2006_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US07084152B2