Sodium Hydroxide → HCID 53996533, compound

Participants

Reaction Steps

Benzo[b]-thien-2-ylglyoxylic acid (3.09 g) and t-butoxyamine hydrochloride (1.98 g) were dissolved in 50% aqueous ethanol (100 ml). The solution was adjusted to pH 4.5 with sodium hydroxide solution and maintained at such for 4 hr. at room temperature. Thin-layer chromatography showed incomplete reaction. t-Butoxyamine hydrochloride (500 mg.) was added and the solution kept at room temperature overnight. The alcohol was removed by evaporation and the aqueous phase adjusted to pH 8 and washed with ether. The aqueous phase was then acidified to pH 1.5 under ether. The ether solution was washed with water and dried. Evaporation gave a cream solid (4.05 g.). Fractional crystallisation from cyclohexane gave the anti-isomer of the title compound (1.6 g.). The mother liquors were combined and evaporated to give a cream solid (2.11 g.) that was treated in ether with excess diazomethane in ether at 0°-5°. The excess reagent was destroyed by acetic acid and the ether solution washed with sodium bicarbonate, water and dried. Evaporation gave an oil (1.75 g.). This was dissolved in methanol (70 ml) and treated with sodium hydroxide solution (N: 7 ml.) at room temperature for 3 hr. Hydrochloric acid (2N: 3.5 ml) was added and the methanol was removed by evaporation. The aqueous residue was partitioned between ether and sodium bicarbonate solution. The ether layer was washed with water and dried. Evaporation gave an oil (0.92 g.) that was dissolved in methanol (20 ml.) and treated with sodium hydroxide (N: 7 ml) at reflux temperature for 3hr. Sodium hydroxide (N: 5ml) was added and the solution refluxed for 6 hr. The methanol was removed by evaporation and the residue partitioned between ether and water. The aqueous phase was acidified (pH 1.5) under ether and the ether layer washed with water, dried and evaporated to give a pale orange crystalline solid (760 mg. 18%). Crystallisation from benzene containing cyclohexane gave syn-2-t-butoxyimino-2-(benzo[b]-thien-2-yl)acetic acid (430 mg.) m.p. 108°-9°, λmax. (EtOH) 231, 253, 297 nm (ε17,000, 7,240, 24,500).

Provenance & Evidence