1,1-Bis(methylthio)-2-nitroethylene → 1-Nitro-2-methylthio-2-[3-(2-oxazolylthio)propylamino]ethylene

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Reaction Steps

Hydrochloric acid (90 ml) was added to potassium thiocyanate in ethanol (1.8 1.) with stirring. Following filtration from inorganic material, glycollaldehyde (35.9 g) was added and the resulting solution was heated under reflux for 24 hours. Concentration, followed by cooling afforded a white solid, which following recrystallisation from ethanol afforded oxazole-2-thiol (30 g), m.p. 143°-144°. (ii) 3-Bromopropylphthalimide (13.4g) was added to a stirred solution of sodium ethoxide (from 1.15 g sodium) and oxazole-2-thiol (5.1 g) in ethanol (100 ml). The resultant solution was heated under reflux for 2.5 hour and concentrated under reduced pressure. The residue was triturated with water (100 ml) to afford 2-(3-phthalimidopropylthio)oxazole (14 g), m.p. 101°. Recrystallisation from ethanol gave the pure oxazole, m.p. 102°-103°. (iii) Hydrazine hydride (5.3 g) was added carefully to a solution of 2-(3-phthalimidopropylthio)oxazole (10 g) in ethanol (173 ml) with stirring. The solution was then heated under reflux for 25 minutes. After cooling, and filtration from phthalhydrazide, the filtrate was concentrated under reduced pressure and the residue was re-evaporated with ethanol to yield crude 2-(3-aminopropylthio)oxazole. (iv) By the procedure of Example 8(i), 2-(3-aminopropylthio)oxazole (2.1 g) is reacted with 1-nitro-2,2-bis-methylthioethylene (2.0 g) to give 1-nitro-2-methylthio-2-[3-(2-oxazolylthio)propylamino]ethylene (2.1 g) which, on reaction with methylamine by the procedure of Example 8(ii) gives the title product (1.8 g).

Provenance & Evidence