Compounds and compositions of azacytosine analogs and derivatives are provided. In one aspect of the invention, analogs or derivatives of decitabine and azacitidine are provided with modification at the 4- and 6-position of the triazine ring, at the 1' 6' position of the ribose ring, or combinations thereof. Methods of synthesizing and manufacturing these analogs and derivatives are also provided. These compounds can be formulated into pharmaceutical compositions that can be used for treating any disease that is sensitive to the treatment with decitabine or azacitidine, such as hematological disorders and cancer.