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

Participants

Reaction Conditions

Reaction Steps

A mixture of (2-benzyloxy-ethyl)-phenyl-amine (21, prepared according to Example 3(c)) (8.0 g, 26 mmol) and 3-bromo-2-hydroxy-cyclohex-1-enecarboxylic acid ethyl ester (4; prepared according to Example 1(d)) (3.2 g, 13 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 (30 mL) and dry zinc chloride (10.6 g, 78 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 (300 mL) and washed with 2 N HCl (100 mL), water (2×100 mL) and aqueous potassium carbonate solution (2×100 mL) then dried and concentrated in vacuo. The crude material was purified by silica gel chromatography eluting with petrol (A) and ethyl acetate (B) (2.5-40% B, 17 CV, 330 g, 100 mL/min) to give 3.49 g (72%) of 9-(2-benzyloxy-ethyl)-2,3,4,9-tetrahydro-1H-carbazole-4-carboxylic acid ethyl ester (25) as an oil. The structure was confirmed by 13C NMR (75 MHz, CDCl3) δC 14.2, 20.5, 21.8, 26.5, 38.6, 42.9, 60.4, 68.7, 73.2, 106.4, 108.8, 118.7, 120.7, 127.4, 127.5, 128.3, 136.2, 136.9, 137.8, 175.0.

Provenance & Evidence