Iodine → Benzo[b]thiophene-6-sulfonic acid benzhydrylamide

Participants

Reaction Conditions

Reaction Steps

To a suspension of magnesium (1.14 g, 46.9 mmol) in dry THF (50 mL) is added iodine (100 mg) followed by slow addition of 6-bromobenzo[b]thiophene (5.00 g, 23.5 mmol) in dry THF (100 mL) at 64° C. (internal temperature) under a nitrogen atmosphere. During the addition, dry toluene (20 mL) is added to the mixture. When addition is completed, the mixture is heated at 68° C. (internal temperature) for 3 hours then cooled to −60° C. where a stream of sulfur dioxide is passed through the solution for 10 minutes. The mixture is allowed to warm to room temperature, the sulfur dioxide bubbling continues for an additional 5 minutes, and the mixture is stirred for 45 minutes. After filtration and concentration, a reddish solid is obtained (8.0 g), which is diluted with dichloromethane (235 mL), treated with N-chlorosuccinimide (3.45 g, 25.8 mmol) at room temperature, and stirred for 2 hours. After filtration and concentration, a reddish solid is obtained (5.8 g), which is diluted with dichloromethane (234 mL), treated with aminodiphenylmethane (20.2 mL, 117 mmol) at 0° C. and the mixture is stirred for 1 hour. Water (200 mL) is added and the mixture is extracted with dichloromethane (3×200 mL). The organic layers are dried (MgSO4) and concentrated. The crude product is suspended in dichloromethane/hexane before it is filtered to give the title compound as a white solid. The filtrate is concentrated and the residue is chromatographed on silica gel (dichloromethane) to give a second crop of title compound (total 2.52 g). ES+(m/z) 378 [M−H].

Provenance & Evidence