To obtain the subject new compound useful as a pharmaceutical composition for curing or preventing a neurological disease, or bacterial or viral infection in a mammal.

A compound of formula I [R1 is NHC(O)R5, etc.; R2 to R4 are each H, fluoro, etc.; R5 is H or a 1-4C alkyl; when R1 is CO2H, R=F and R3 and R4 are not H, and when R1 is NH2, R2=F and R3≠H] or its pharmaceutically permissible salt, e.g. methyl 3-fluoro-5-hydroxyadamantane-1-carboxylate. The compound is obtained, for example, by treating a compound of formula II with diethylaminosulfur trifluoride to obtain the corresponding fluoro substituted ester, hydrolyzing this to convert into an acid of formula III, treating the acid with triethylamine diphenylphosphorylamide and benzyl alcohol, heating the reaction product up to the reflux temperature to obtain a benzylcarbamate intermediate and converting this into an amine of formula IV having a fluoro group on a bridge head carbon of the adamantane.