(R)-2-(Toluene-4-sulfonyloxymethyl)-2,3,8,9-tetrahydro-7H-1,4-dioxino[2,3-e]indol-8-one (1.2 g, 3.2 mmole) and tryptamine (1.5 g, 9.6 mmole) in DMSO (50 ml) were placed in a three-neck flask equipped with a condenser, a thermometer and a nitrogen bubbler immersed into the solution. The reaction mixture was heated at 75° C. for 5 hours, cooled to room temperature and partitioned between water and ethyl acetate. The ethyl acetate layer was separated, dried over anhydrous sodium sulfate, concentrated in vacuum and column chromatographed on silica gel using first ethyl acetate and subsequently 2.5%, 5%, 10% methanol in ethyl acetate as eluants. The free base of the desired product was obtained (0.85 g, 2.3 mmole) as an oil which was dissolved in 50 ml of ethanoldiethyl ether (1/1) solution and treated with 10.3 ml of 0.25 M of fumaric acid in ethanol. Addition of hexane gave 0.30 g of the (S) enantiomer of the title compound as an off-white solid hemi-fumarate, three quarter hydrate, m.p. 175-176° C.
