. . . "en Y is a sulfur atom, (R1)m is selected from the group consisting of: 2-methyl, 3-methyl, 4-fluoro, 2-chloro, 3-chloro, 2,5-dichloro 2,6-dichloro, 3,4-dichloro, 2-bromo, 2-methoxycarbonyl, and 4-(N,N-diethylaminosulfonyl); or an acid addition salt of said derivative." .