Dimethyl Sulfoxide → 1-ethyl-6-methoxy-N-(4-hydroxycyclohexylmethyl)-1H-pyrazolo[3,4-b]quinolin-4-amine

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Reaction Steps

A mixture of 4-hydroxycyclohexylmethylamine (2.2 g, 17.05 mmol), 1-ethyl-4-chloro-6-methoxy-1H-pyrazolo[3,4-b]quinoline (2.0 g, 7.66 mmol) and DMSO is heated at 110°-120° C. under a nitrogen atmosphere for 16 hours. The reaction mixture is poured into ice water, and the mixture is extracted with CH2Cl2 (4×50 ml). The organic layers are combined, dried over MgSO4 and evaporated to dryness. The residue is purified by column chromatography on silica gel eluting with CH2Cl2 /methanol (9/1), followed by a second silica gel column eluting with ethyl acetate to afford 1.3 g of crude product. The crude product is dissolved in warm methanol, cooled to room temperature and treated with an equivalent amount of methanesuflonic acid. Ether is added to the mixture and the solid which forms is collected by filtration, washed with ether and recrystallized from isopropanol to afford 0.85 g of 1-ethyl-6-methoxy-N-(4-hydroxycyclohexylmethyl)-1H-pyrazolo[3,4-b]quinolin-4-amine. CH3SO3H, as yellow crystals, m.p. 256°-258° C. (dec.)

Provenance & Evidence