On topography and functionality in the B-D rings of cephalostatin cytotoxins

Analogues 12'beta-hydroxycephalostatin 1 (9), 7'-deoxyritterazine G (10), a nd 14-epi-7'-deoxyritterazine B (11) were prepared via our protocol for uns ymmetrical pyrazine synthesis. Cytotoxicity against human tumors was also d etermined for the first time for ritterazines, with femtomolar potency and a high correlation to cephalostatins observed. The SAR of these and related . compounds provide insight into the importance of topography and certain c hemical functionality in the B-D and B'-D' rings of cephalostatin type anti neoplastics. (C) 1999 Elsevier Science Ltd. All rights reserved.