Triethylamine → [7-Bromo-9-(4-methyl-piperazin-1-ylmethyl)-2,3-dihydro-[1,4]dioxino[2,3-g]quinolin-8-yl]-methanol

Participants

Reaction Steps

To a mixture of 7-bromo-9-bromomethyl-2,3-dihydro[1,4]dioxino[2,3-g]quinoline-8-carboxylic acid methyl ester hydrobromic acid salt (Intermediate 10, 10 g, 19.6 mmol) in dichloromethane (DCM, 100 mL) is added triethylamine (5.4 mL. 39.2 mmol) followed by N-methylpiperazine (2.79 mL, 25.5 mmol). After stirring 30 min, water (50 mL) is added and the mixture is stirred 10 min. The layers are separated and the aqueous phase is extracted with DCM (50 mL). The organic phases are combined and washed with water (2×50 mL). The organic solution is then concentrated to an oil. The oil is diluted with DCM (50 mL) and stirred while diisobutylaluminum hydride (1.0 M in dichloromethane, 53 mL. 53 mmol) is added slowly while keeping the reaction temperature below 30° C. using an ice bath. The reaction is stirred for 10 min and then slowly poured into an aqueous solution (75 mL) saturated with potassium sodium tartrate tetrahydrate (Rochelle's salt). The temperature is kept <30° C. with an ice bath during the addition. The mixture gels and is stirred overnight at room temperature. The layers are separated and the aqueous phase is extracted with DCM (2×75 mL). The organics are combined and washed with water (2×50 mL). The organic phase is then concentrated under vacuum (crystallization occurs during concentration) to about 20 mL and the rest of the product crystallized out by adding tert-butyl methyl ether. The slurry is filtered and dried on high vacuum at room temperature overnight to provide 6.87 g (86%) of [7-bromo-9-(4-methyl-piperazin-1-ylmethyl)-2,3-dihydro-[1,4]dioxino[2,3-g] quinolin-8-yl]-methanol as a tan solid.

Provenance & Evidence