Patent ID: 7754719

Claim:
A compound of the formula I wherein R 1 and R 2 are independently selected from the group consisting of phenyl that is unsubstituted or substituted by one or more substituents independently selected from cyano, C 1 -C 7 -alkoxy, nitro and halo, fluorenyl pyridinyl that is unsubstituted or substituted by one or more substituents independently selected from hydroxy, halo, nitro, cyano, trifluoromethyl, C 1 -C 4 -alkyl and C 1 -C 4 -alkoxy, 1-alkyl-oxo-dihydropyridinyl, benzo[1,2,5]oxadiazolyl, benzo[1,2,5]thiadiazolyl, imidazo[1,2-b]pyridazin-8-, -7- or -6-yl, 4-[1,2,5]-thiadiazolo-[3,4-b]pyridin-7-, -6- or -5-yl, xanthenyl, thioxanthenyl, benzo[1,3]dioxol-4- or -5-yl, and 2,3-dihydro-benzo[1,4]dioxin-5- or -6-yl; and each of n and m is 1; or a salt thereof.