Sodium Hydroxide → 3-Methyl-5,6,7,8-tetrahydroquinoline

A solution of 15% n-butyl lithium in hexane (51 ml. ca. 0.12 m) was added portionwise to a solution of 3-methyl-5,6,7,8-tetrahydroquinoline (14.7 g., 0.1 m) in ether (100 ml.) and the mixture allowed to stand at room temperature for 1 hour then added dropwise to a cooled, stirred solution of methyl chloroformate (9.45 g., 0.1 m) in ether (100 ml.). The mixture was stirred at 50° C. for 1 hour. The reaction mixture was diluted with water (20 ml.) and then treated with 2N HCl until acidic. The ethereal solution was separated and washed with 2N HCl (2× 25 ml.). The combined aqueous washings were extracted with ether and the ethereal extracts discarded. The aqueous solution was adjusted to pH 9.0 with Na2CO3 and extracted with chloroform (3× 50 ml.) and the combined extracts dried and evaporated to give a pale yellow oil (16 g) which on GLC examination (3% SE30) showed a mixture of unreacted tetrahydroquinoline (45%), the title compound (23%) and the 8,8-dicarboxylic ester (20%). The mixture was treated with 10% sodium hydroxide (75 ml.). and heated at reflux with stirring for 4 hours, cooled and extracted with ether (3× 50 ml.). The combined ethereal extracts were dried, evaporated and distilled to give unreacted 3-methyl-5,6,7,8-tetrahydroquinoline (7 g.) b.p. 116°/18 mm Hg. The basic solution was adjusted to pH 8.5-9.0 with concentrated HCl and evaporated to dryness and the residue treated with methanol previously saturated with dry HCl (50 ml.) and allowed to stand at room temperature for 5 hours. The solvent was removed and the residue dissolved in water (20 ml.) and extracted with ether (2× 50 ml.). The aqueous solution was adjusted to pH 9.0 with Na2CO3 and extracted with chloroform (3× 25 ml.) and the combined extracts dried and evaporated to give the title compound (3 gm.).

1. temperatureand heated
2. temperatureat reflux
3. temperaturecooled
4. extractionextracted with ether (3× 50 ml.)
5. customThe combined ethereal extracts were dried
6. customevaporated
7. distillationdistilled

ORD record

ord-80d7db501ee8407da60375fcbf18fdc8

Source dataset

uspto-grants-1977_06

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US04029668