A method for treating cancer including administering to a patient in need thereof an effective amount of a compound having the formula: wherein R1, R2, Ya, Xa, and J− are as defined herein, and may be where R1 and R2 are independently selected from methyl, ethyl, n-propyl, or i-propyl; Xa is N or CH; Ya is hydrogen or independently selected from halogen, cyano, hydroxyl, alkyl of 1 to 6 carbon atoms, alkoxy of 1 to 6 carbon atoms, heteroaryl of 6 members and aryl; n is 1 or 2; wherein J− is fluoride, chloride, bromide, iodide, acetate, sulfate or sulfonate such as tosylate, mesylate, besylate.