It was a significant challenge to keep these conjugated molecules
approaching the Ro5, and in all cases lipophilicity increased
compared to astemizole. Clearly this would need to be addressed
in further design cycles, due to the potential for high lipophilicity
to increase both off-target pharmacology and the potential for adverse
toxicological outcomes.14 However, it was felt the designed
set of compounds 5–8 would allow for proof-of-principle of this
hybrid approach to be established, which could then trigger further
work to improve drug-like properties.
The synthetic route employed to access the target compounds
5–8 is outlined in Scheme 1. Alkylation of 2-chlorobenzimidazole
9 was effected with 4-fluorobenzyl bromide 10