Acetic Acid → N-(7-Hydroxy-4,5,6,7-tetrahydro-1-benzothiophen-4-yl)urea

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Reaction Steps

7-Keto-4,5,6,7-tetrahydrobenzo[b]-thien-4-ylurea (0.5 grams, 2.38 mm) is suspended in ethanol (50 ml.) and to the stirred solution is added solid sodium borohydride (0.5 grams, 13.2 mm). After stirring overnight the mixture is treated cautiously with 5% aqueous acetic acid (20 ml.). After stirring 15 minutes the solvent is removed, the residue dissolved in a small volume of methanol and percolated through a 11/2 ' × 13/4 silica gel dry column eluting with 20% methanolic methylene chloride. The resulting gum is crystallized from ethyl acetate/methanol to afford 66 mg. (13% Y) of the more polar (L.L.C) alcohol (B), melting point 194° C. to 197° C. The mother liquor material is separated into its two major components 7-hydroxy-4,5,6,7-tetrahydrobenzo[b]thien-4-ylurea by high pressure liquid chromatography on "Spherosil XOA 400" using the solvent system: hexane (1800 ml.)/methanol (425)/chloroform (1000) flow rate ~ 13 ml./min.). This procedure affords the less polar alcohol A (29 mgs. 6% yield) melting point, 162° C. to 169° C. (methanol/ethyl acetate), and the more polar alcohol B (50 mg., 10% yield), melting point 197° C. to 198° C.

Provenance & Evidence