O-methylhydroxylammonium chloride → 5,7-dihydro-2-[[(4-methoxy-3,5-dimethyl-2-pyridyl)methyl]thio]-5,5,7,7-tetramethylindeno[5,6-d]imidazol-6(1H)-one O-methyl oxime

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Reaction Steps

5 g of 5,7-dihydro-2-[[(4-methoxy-3,5-dimethyl-2-pyridyl)methyl]thio]-5,5,7,7-tetramethyli ndeno[5,6-d]imidazol-6(lH)-one and 40 g of 0-methylhydroxylamine hydrochloride in 250 ml of methanol were boiled at reflux for 16 hours under argon. After removing the solvent in vacuo the residue was partitioned between methylene chloride and water and the aqueous phase was extracted three times with methylene chloride. The combined organic extracts were made neutral with saturated sodium bicarbonate solution in the presence of ice and under argon gasification. After repeated extraction with methylene chloride the organic phases were dried over sodium sulfate and evaporated in vacuo. A red impurity was removed by chromatography on silica gel with ethyl acetate. The separation of the reaction product from starting material was carried out on silica gel using toluene/methyl isobutyl ketone/pyridine (80:18:2) as the elution agent. The purity of the fractions was assayed by thin-layer chromatography using the system ethyl acetate/ methyl isobutyl ketone/pyridine (80:18:2). By crystallization from acetone/water there was obtained 5,7-dihydro-2-[[(4- methoxy-3,5-dimethyl -2-pyridyl)methyl]thio]-5,5,7,7-tetramethylindeno[5,6-d]imidazol-6(lH)-one O-methyl oxime of melting point 110-112° .

Provenance & Evidence