Phenylhydrazine → Indole

Temperature

50 °C

To a solution of 1 (90 mg, 0.27 mmol) in acetic acid (2 mL) was added a solution of phenylhydrazine (0.026 mL, 0.27 mmol) in acetic acid (1 mL) and the mixture heated at 50° C. for 1 hour. The reaction was cooled to room temperature then boron trifluoride etherate (0.060 mL, 0.46 mmol) added and the reaction heated at 80° C. for 16 hours. The mixture was diluted with CH2Cl2 (25 mL) and washed with satd NaHCO3 (3×15 mL, caution: vigorous gas evolution). The organic layer was dried (Na2SO4), filtered, and concentrated in vacuo. The residue was chromatographed on silica gel, eluted with 40% EtOAc/hexanes, to give 2 (87 mg, 78% yield) as an off-white solid. Rt=1.96 min using Phenomenex 30×4.6 5u column with flow rate of 5 mL/min over 2 min gradient. 0 to 100% B. Solvent A=10/90/0.1% MeOH/H2O/TFA. Solvent B=90/10/0.1%. [M+H]=411.

1. temperatureThe reaction was cooled to room temperature
2. temperaturethe reaction heated at 80° C. for 16 hours
3. washwashed with satd NaHCO3 (3×15 mL, caution: vigorous gas evolution)
4. dry with materialThe organic layer was dried (Na2SO4)
5. filtrationfiltered
6. concentrationconcentrated in vacuo
7. customThe residue was chromatographed on silica gel
8. washeluted with 40% EtOAc/hexanes

ORD record

ord-78e60672125a4baa8390456387d4d030

Source dataset

uspto-grants-2013_01

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US08357704B2