Carbon Dioxide → Methyl 5,6,7,8-tetrahydroquinoline-8-carboxylate

A solution of 5,6,7,8-tetrahydroquinoline (14 g.) in dry ether (100 ml.) was added dropwise over 1/2 hour to an ethereal solution of phenyl lithium (prepared from bromobenzene (42 g.) and lithium (3.7 g.) in dry ether (300 ml.) and the reaction mixture stirred at room temperature for a further one hour. The cooled reaction mixture was saturated with dry CO2 gas, evaporated in vacuo and the residue treated with methanol previously saturated with dry HCl (500 ml.) and the solution heated at reflux for 12 hours. The solvent was removed in vacuo and the residue dissolved in water (50 ml.), extracted with ether (3 × 150 ml.) and the extracts discarded. The aqueous solution was made basic and extracted with ether (3 × 100 ml.). The combined ethereal extracts were dried, evaporated in vacuo and the residual oil distilled giving methyl-5,6,7,8-tetrahydroquinoline-8-carboxylate as a colourless oil (13 g.) b.p. 92° C/0.05 mm. The hydrochloride was prepared by saturating an ethereal solution with dry HCl gas and recrystallising the resultant solid from methanol-ether to give the hydrochloride of the title compound as colourless needles mpt. 173° C. Found: C, 58.2; H, 6.3; N, 6.3%. C11H13NO2.HCl requires C, 58.0; H, 6.2; N, 6.2%.

1. customThe cooled reaction mixture
2. customevaporated in vacuo
3. additionthe residue treated with methanol previously saturated with dry HCl (500 ml.)
4. temperaturethe solution heated
5. temperatureat reflux for 12 hours
6. customThe solvent was removed in vacuo
7. dissolutionthe residue dissolved in water (50 ml.)
8. extractionextracted with ether (3 × 150 ml.)
9. extractionextracted with ether (3 × 100 ml.)
10. customThe combined ethereal extracts were dried
11. customevaporated in vacuo
12. distillationthe residual oil distilled

ORD record

ord-9aa1ed0ff6184812a7d19d14336b7d3b

Source dataset

uspto-grants-1977_02

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04009169