Sodium Hydroxide → 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

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Reaction Steps

18.0 g of 5.7-dihydro-2-mercapto-5,5,7,7-tetramethylindeno[5,6-d]imidazol-6(lH)-one were suspended in 400 ml of ethanol and treated while cooling with ice with 15.6 g of 2-chloromethyl-4-methoxy-3,5-dimethylpyridine hydrochloride. Thereafter, a solution of 5.6 g of sodium hydroxide in 150 ml of water was added dropwise thereto, the mixture was left to boil at reflux overnight and subsequently evaporated to dryness in vacuo. The residue was dissolved in 1000 ml of methylene chloride; the solution was washed firstly with 500 ml of 1.5N sodium hydroxide solution and then with 3 x 500 ml of water, dried over sodium sulfate and evaporated in vacuo. The product was purified on 300 g of silica gel with ethyl acetate/methylene chloride (1:1) as the elution agent. Crystallization from methylene chloride/petroleum ether gave 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 of melting point 166-168° .

Provenance & Evidence