1,2,3,4-Tetrahydroisoquinoline → Benzamide, N-(1,2,3,4-tetrahydro-2-methylisoquinolin-7-yl)-3,4,5-trimethoxy-

Participants

Reaction Steps

7-Amino-2-methyl-1,2,3,4-tetrahydroisoquinoline (2 g), prepared from 7-nitro-2-methyl-isoquinolinium p-toluenesulfonate as described for the 5-nitro isomer in Example 4 was dissolved in dry benzene (50 ml) and 0.5 g of dry potassium bicarbonate was added. A 0.1 mole excess of 3,4,5-trimethoxybenzoyl chloride was dissolved in benzene (50 ml) and this solution was added to the solution of the tetrahydroisoquinoline. A brown precipitate formed immediately and the mixture was refluxed for 3 hours. The benzene was removed in vacuo leaving a tan residue which was suspended in 10% sodium carbonate solution to remove excess acid chloride and stirred for 1 hour. The insoluble residue was a brown oil which was extracted from the aqueous sodium carbonate with chloroform. The chloroform was dried over anhydrous magnesium sulfate and the chloroform was distilled off to leave a viscous red oil which crystallized to a white powder (2.7 g) when washed with cold ether. The white solid was recrystallized from ethanol-ether to yield the desired product as a white powder, m.p. 157.5°-158° C.

Provenance & Evidence