3-(3-Methoxy-5,6,7,8-tetrahydronaphthalen-2-yl)-2-azido-2-propenoic acid ethyl ester → 2-Carboethoxy-4-methoxy-6,7,8,9-tetrahydro-1h-benz[g]indole

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Reaction Steps

A solution of 3-(3-methoxy-5,6,7,8-tetrahydronaphthalen-2-yl)-2-azido-2-propenoic acid ethyl ester (34.2 g, 0.113 mmol) in toluene (200 mL) was treated with rhodium(II) acetate dimer (300 mg, 0.679 mmol) at 95° C. for 4 h then at reflux for 1 h. The mixture was cooled to room temperature and the resulting solids were collected via vacuum filtration. The filtrate was concentrated to give a further precipitate that was collected via vacuum filtration. The filtrate was filtered through a silica gel plug and concentrated to provide an additional portion of product to give a total of 25.8 g (83%) of the title compound: mp 202-203° C. 1H NMR (CDCl3) δ 8.65 (bs, 1H, —NH), 7.30 (d, J=2.2 Hz, 1H), 6.24 (s, 1H), 4.38 (q, J=7.0 Hz, 2H), 3.91 (s, 3H), 2.84 (t, J=5.9 Hz, 2H), 2.76 (t, J=5.5 Hz, 2H), 1.90 (m, 4H), 1.40 (t, J=7.0 Hz, 3H); MS ES+ m/e 274 (p+1); IR (CHCl3, cm−1) 3459, 2937, 1698.

Provenance & Evidence