Ring size changes in the development of class I HDAC inhibitors

Five pathways involving different ring structures led to generation of fourteen thienylbenzamides (7–20) which display the structure-activity relationships class I HDAC inhibitors. All synthesised compounds inhibit HDAC1 and HDAC2 selectively over other isoforms many DLD1 HCT116 cells more effectively than a parent compound. Compounds 8 16 by activation apoptosis pathway.