Spiro compounds useful as antagonists of the H1 receptor and their asymmetric preparation, pharmaceutical compositions and use in the treatment of sleep disorders

The invention provides compds. of formula I and their pharmaceutically acceptable salts thereof, for treating diseases and conditions of the central nervous system (CNS), in particular sleep disorders. Compds. of formula I wherein X is CH2, O and S; m and n are independently 0-2; each of R1 and R2 is independently halo, C1-3 alkyl and C1-3 alkoxy; when substitutent NR3R4 is absent, A is (un)substituted satd. or partially satd. 5- to 6-membered heterocyclyl; when substitutent NR3R4 is present, A is satd. or partially satd. 5- to 6-membered carbocyclyl; R3 and R4 are independently H and C1-3 alkyl; R3R4 may taken together with the nitrogen atom attached to form (un)substituted satd. or partially satd. 4- to 6-membered heterocyclyl; and their pharmaceutically acceptable salts thereof, are claimed. Example compd. II was prepd by a general procedure (procedure given). All the invention compds. were evaluated for their H1 receptor antagonistic activity. From the assay, it was detd. that II and all other tested compds. exhibited the fPki values of > 5.5.