Reaction #2952

Reaction equation

(±)-trans-2-ethyl-4a-(3-methoxyphenyl)-6-oxo-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline

proton sponge

vinylchloroformate

→

title compound

Yield 70.8%

(±)-trans-4a-(3-Methoxyphenyl)-6-oxo-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline hydrochloride

Yield 70.8%

Solvents

1,2-dichloroethane

Conditions

Workup

1. 1
   Temperaturerefluxed for 3 h
2. 2
   Otherthe solvent was removed in vacuo
3. 3
   Extractionextracted with Et2O
4. 4
   WashThe organic layer was washed with 3% HCl
5. 5
   Dryingwas dried over Na2SO4
6. 6
   Otherthe solvent was removed in vacuo
7. 7
   workup.DISSOLUTIONThe dark residue was dissolved in EtOH
8. 8
   workup.ADDITION3 ml of concentrated HCl were added
9. 9
   Temperaturethe solution refluxed for 3 hours
10. 10
    OtherThe solvent was removed in vacuo

Procedure

A solution of 1.2 g (4.2 mmol) of (±)-trans-2-ethyl-4a-(3-methoxyphenyl)-6-oxo-1,2,3,4,4a,5,6,7,8,8a-decahydroisoquinoline and 1.8 g (12.6 mmol) of proton sponge in 34 ml of 1,2-dichloroethane was treated with 1.4 ml (16.8 mmol) of vinylchloroformate at 0° C. under nitrogen atmosphere. The reaction mixture was stirred at this temperature for 15 min and then refluxed for 3 h, the solvent was removed in vacuo, the residue was taken up in water and extracted with Et2O. The organic layer was washed with 3% HCl, then was dried over Na2SO4 and the solvent was removed in vacuo. The dark residue was dissolved in EtOH, 3 ml of concentrated HCl were added and the solution refluxed for 3 hours. The solvent was removed in vacuo, obtaining 0.88 g of the title compound which was used as such in the subsequent step. M.p.=90° C. dec.

Source