Ethylenediamine → 4-[N'-(2-aminoethyl)thioureido]-1-t-butoxycarbonyl-2,3-dihydro-7-methylindole

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Reaction Steps

A solution of 1-t-butoxycarbonyl-2,3-dihydro-4-isothiocyanato-7-methylindole (1.70 g; 5.86 mmol) in methylene chloride (10 mL) is slowly added to a solution of ethylenediamine (1.76 g, 29.3 mmol) in methylene chloride (10 mL). After 30 minutes, the solution is washed with four 50-mL portions of aqueous potassium carbonate, dried over anhydrous potassium carbonate, filtered and rotary evaporated to yield an off-white solid. The crude residue is purified via silica gel column chromatography using 10% methanol (ammonium hydroxide treated)/methylene chloride as the eluent. The appropriate fractions are combined and the solvents removed by rotary evaporation to yield 1.92 g of 4-[N'-(2-aminoethyl)thioureido]-1-t-butoxycarbonyl-2,3-dihydro-7-methylindole as a white solid (94% yield).

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