Benzaldehyde → 8-Benzylidene-2-methyl-5,6,7,8-tetrahydro-quinoline

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Reaction Steps

A solution of Intermediate 200A1 (27.5 g, 187 mmol), benzaldehyde (18.4 mL, 181 mmol) and acetic anhydride (32.5 mL, 290 mmol) was heated at 155° C. for 4 h. The mixture was cooled to room temperature, mixed with crushed ice, basified with 2M NaOH to pH>8. The aqueous layer was extracted with hexane/ethyl acetate. The pooled organic layers were dried over MgSO4, filtered, evaporated and purified by chromatography on SiO2 to give 8-benzylidene-2-methyl-5,6,7,8-tetrahydro-quinoline (Intermediate 200A2) as the major product. This material was carried onto the next step. Note: 2-styryl-5,6,7,8-tetrahydro-quinoline (removed by chromatography on SiO2 with 1.5% acetone in hexanes) and 8-benzylidene-2-styryl-5,6,7,8-tetrahydro-quinoline were also produced as side products.

Provenance & Evidence