41175-50-2

pink to beige or brown fine crystalline powder

8-Hydroxyjulolidine is used as an intermediate in the preparation of aminocoumarins via microwave-accelerated Pechmann reaction. It is also employed as a starting material for coumarin C-ribosides.

The general procedure for the synthesis of 1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-8-ol from 8-methoxyjulolidine was as follows: 8-methoxyjulolidine (10 g, 50 mmol) was dissolved in a mixed solution consisting of 50 mL of 47% hydriodic acid, 80 mL of concentrated hydrochloric acid and 200 mL of water. The reaction mixture was heated to reflux and the progress of the reaction was monitored by thin layer chromatography (TLC). After 15 hours of reaction, 50 mL of concentrated hydrochloric acid was added to the mixture. The total reaction time was 60 hours. Upon completion of the reaction, the solution was cooled in an ice bath and first neutralized to pH 6 with 50% sodium hydroxide solution, followed by the addition of phosphate buffer (prepared by dissolving 6.9 g NaH2PO4-H2O and 1.4 g Na2HPO4 in 100 mL of water). The product was extracted with dichloromethane and the organic phase was washed with brine, dried over anhydrous sodium sulfate and concentrated under reduced pressure to remove the solvent. The resulting crude product was redissolved in dichloromethane and extracted repeatedly with 10% sodium hydroxide solution until the aqueous phase was colorless. Subsequently, the organic phase was acidified, dried and extracted again, and the solvent was removed as described above, resulting in the product 1,2,3,5,6,7-hexahydropyrido[3,2,1-ij]quinolin-8-ol (6.24 g) in 67% yield and with a melting point of 126-130°C. The product was extracted with sodium sulfate under reduced pressure.

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[5] Patent: US2018/280543, 2018, A1. Location in patent: Paragraph 0041; 0098