Four oxazolidinone analogues(6, 7, 8, 9), which are isosters of 5, were synthesized by the reaction of 2-chloroalkyl-3,5-dimethyl-4-methoxypyridine with the corresponding benzox azolidinone or oxazolidinone, respectively, and were evaluated for their inhibitory activities toward proton pump enzyme under in vitro condition. Isosteric substitution of the benzothiazolidine moiety in 5 with benzoxazolidinone rendered the molecule relatively inactive.