Benzene → Gramine

Participants

Reaction Conditions

Reaction Steps

To a solution of N-benzylideneisopropylamine (7.5 g, 51 mmol) in benzene (10 mL) at 0° C. under a nitrogen blanket was added a solution of indole (5.0 g, 43 mmol) AcOH (30 mL) over a 3-hour period, after which the stirring was continued at 0° C. for an additional 3 hours. The bulk of the solvent was removed under reduced pressure and the remaining reaction mixture was poured into 400 mL of ice water. The mixture was extracted with Et2O (3×75 mL), and the aqueous layer was cooled to 0° C. and made basic with 30% aqueous NaOH to a pH 11–12 range. The precipitate was extracted with CH2Cl2 (2×75 mL) and the combined organic extracts were dried over Na2SO4, filtered, and the solvent was removed under reduced pressure to provide gramine Intermediate 6 as a yellow semisolid (3.06 g, 27%): TLC Rf (1:1 CH2Cl2/EtOAC)=0.45.

Provenance & Evidence