“…The general strategies for the CYT syntheses are presented below based upon final ring closure of the tricyclic structure (A, B or C) in Figure 4. Among the total synthesis of CYT reported are syntheses using pyridine-derived A ring [19,24,27], glutarimide or pyridone-derived A ring [23,25], pyridine derived B-ring [45,46], piperidine derived C-ring [26] and constructions of bispidine core by O'Brien and coworkers [47,48]. The synthetic routes to obtain Ring A were fully developed by O'Brien and coworkers.…”