N-Phenyl-2-benzyloxyethylamine → 9-(2-Benzyloxy-ethyl)-2-methyl-2,3,4,9-tetrahydro-1H-carbazole-4-carboxylic acid diethylamide

Participants

Reaction Conditions

Reaction Steps

A mixture of 3-bromo-2-hydroxy-5-methyl-cyclohex-1-enecarboxylic acid diethylamide (47) (4.0 g, 14 mmol) and (2-benzyloxy-ethyl)-phenyl-amine (21; prepared according to Example 3(c)) (6.3 g, 28 mmol) was stirred under N2 at 50° C. for 3 h and the reaction turned brown. The resulting mixture was dissolved in propan-2-ol (14 mL) and dry zinc chloride (5.72 g, 42 mmol) was added. The mixture was heated to reflux under N2 for 16 h and then concentrated in vacuo. The residue was dissolved in ethyl acetate (200 mL) and washed with 2 N HCl (50 mL), water (2×50 mL) and aqueous potassium carbonate solution (2×50 mL) then dried and concentrated in vacuo. The crude mixture was purified by SCX cartridge (40 mL) and then silica gel chromatography eluting with petrol (A) and ethyl acetate (B) (10-50% B, 100 g, 12 CV, 85 mL/min) to afford 467 mg (8%) of 9-(2-Benzyloxy-ethyl)-2-methyl-2,3,4,9-tetrahydro-1H-carbazole-4-carboxylic acid diethylamide (48) as a white solid. The structure was confirmed by 1H NMR (300 MHz, CDCl3) δH 1.20-1.40 (9H, m, CH3 and N(CH2CH3)2), 1.90-2.20 (3H, m, 2-CH and 3-CH2), 2.35-2.45 (1H, m, 1-CH2), 2.85-2.95 (1H, m, 1-CH2), 3.40-3.70 (4H, m, N(CH2CH3)2), 3.70-3.80 (1H, m, 4-CH), 4.10-4.30 (4H, m, NCH2CH2OBn), 4.43 (2H, s, OCH2Ph), and 7.00-7.30 (9H, m, CHCHCHCH and Ph).

Provenance & Evidence