Sibopirdine, also known as EXP921, is a nootropic drug.
Patent:
4,5-Diazafluoren-9-one [50890-67-0] (1) is condensed with 4 molar equivalents of 4-picoline [108-89-4] (2) in the presence of 2 equivalents of acetic anhydride and acetic acid. The intermediate from this step may originally be a tertiary alcohol which then dehydrates under the reaction conditions to give [150896-71-2] (3). The olefin can then be reduced either by catalytic hydrogenation over 5% Pd/C or by sodium borohydride in alcohol to give [150896-72-3] (4). Alkylation with 4-picolyl chloride [10445-91-7] (5) in the presence of sodium hydroxide completed the synthesis of sibopirdine (6).