Trifluoroacetic acid → 4-[4-(9-Oxa-3,7-diazabicyclo[3.3.1]non-3-yl)butyl]benzonitrile

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Reaction Steps

A 2 L three-necked flask was equipped with a magnetic stirrer, a thermometer and an addition funnel. The flask was charged with tert-butyl 7-[4-(4-cyanophenyl)butyl]-9-oxa-3,7-diazabicyclo[3.3.1]-nonane-3-carboxylate (34 g, 88 mmol, from step (iv) above) and dichloromethane (440 mL). Trifluoroacetic acid (132 mL) was added slowly at room temperature. The solution was stirred for three hours at which point TLC analysis showed complete consumption of starting material. The contents were transferred to a single-necked flask and concentrated under vacuum. The residue was dissolved in dichloromethane (500 mL) and washed with saturated sodium bicarbonate solution. The aqueous layer was separated and extracted with dichloromethane (2×200 mL). The combined organic layers were washed with brine (200 mL), dried over magnesium sulfate and concentrated under vacuum to afford 25.8 g (100% yield) of sub-title compound as an off-white solid. The crude material was used in the next step without farther purification.

Provenance & Evidence