Patent ID: 7550479

Claim:
A method of preparing a compound having a structural formula: comprising the steps of: (a) esterifying D-tryptophan in methanol and thionyl chloride to provide D-tryptophan methyl ester hydrochloride; (b) reacting the D-tryptophan methyl ester hydrochloride with piperonal in refluxing isopropyl alcohol to provide cis-1-(1,3-benzodioxol-5-yl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylic acid methyl ester; (c) reacting the product of step (b) with chloroacetyl chloride and triethylamine to provide (6R, 12aR)-2,3,6,7,12,12a-hexahydro-6-(3,4-methylenedioxyphenyl)-pyrazino-[2′,1 ′:6,1]pyrido[3,4-b]indole-1 ,4′dione (d) reacting the product of step (c) with methylamine to provide the compound.