Tunable regioselectivity associated with the reaction of 2,3-dihalo-1-(phenylsulfonyl)-1-propenes with ambident nucleophilic reagents (original) (raw)

1992, The Journal of Organic Chemistry

The solution was warmed to room temperature over 12-16 h. Quench and workup were identical to that described above for DEAC. Deprotection of Lactam 4c: Formation of 6. Lactam 4c (0.100 g, 0.30 mol) was dissolved in 20 mL of liquid ammonia. Sodium metal (0.069 g, 3.0 mmo1,lO equiv) was added, and a deep blue color was obtained. The solution was allowed to reflux for 1 h with the persistence of blue color. The reaction was quenched with ammonium chloride (0.200 g, 13 equiv) and allowed to warm to room temperature in a hood. The residue was triturated with acetonitrile (5 mL), and the decanted solution was concentrated to a residue. The residue was triturated with methanol (5 mL) and was filtered through cotton. The filtrate was concentrated to yield an oil. The oil was purified by column chromatography (silica gel, CHC13/MeOH, 9/1) to yield 0.030 g of semisolid (57% yield). Purity was >90% as established by TLC: 'H NMR (CDC13) 6 6.20 (bs, 1-H), 3.79 (m, 2-H), 3.35 (s,3-H), 3.12 (bs, 1-H), Preparation of 7. Deprotected compound 6 (0.030 g, 0.14 mmol) was dissolved in anhydrous THF (1 mL). 1,l'-Carbonyldiimidazole (0.024 g, 0.14 mmol) was added, and the solution was warmed to 35-40 "C for 24 h. The solution was concentrated in vacuo, and the crude oil was purified by column chromatography (silica gel 230 m, CHC13/MeOH, 9/1). The desired fractions were combined and concentrated to yield 15 mg of oil (50% yield). Purity was >90% as determined by TLC exact mass calculated for C12H20N04 (M + l), 242.13923, exact mass