Dichloromethane → 4-(2-{4-[(6,7-dihydro[1,4]dioxino[2,3-c]pyridazin-3-ylmethyl)amino]-1-piperidinyl}ethyl)-6-(methyloxy)pyrido[2,3-b]pyrazin-3(4H)-one Dihydrochloride

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Reaction Steps

A solution of 4-[2-(4-amino-1-piperidinyl)ethyl]-6-(methyloxy)pyrido[2,3-b]pyrazin-3(4H)-one (50 mg, 0.1648 mmoles) and 6,7-dihydro[1,4]dioxino[2,3-c]pyridazine-3-carbaldehyde (30.1 mg, 0.181 mmoles) in anhydrous DCM (5 ml) and anhydrous MeOH (0.5 ml) was stirred at rt for 5 minutes. Sodium triacetoxyborohydride (115 mg, 0.543 mmoles) was added and the mixture was stirred, under argon, for 24 hours. A further 6,7-dihydro[1,4]dioxino[2,3-c]pyridazine-3-carbaldehyde (15 mg, 0.09 mmoles) and sodium triacetoxyborohydride (50 mg, 0.236 mmoles) were added and reaction was stirred for 5 hours, treated with sat. aq. NaHCO3 solution (2 ml) and 9:1 DCM:MeOH (5 ml). The layers were separated and the aqueous layer was washed with 9:1 DCM:MeOH (10 ml) and 5:1 DCM:MeOH (2×20 ml). The organic extracts were combined, passed through a hydrophobic frit and evaporated to an orange gum. Purification on a 20 g silica column eluted with a 20:1 to 10:1 DCM:MeOH gradient elution gave the free base of the title compound as a pale yellow gum (26.1 mg, 35%)

Provenance & Evidence