Dynemicin cascade

Scheme 7-71 Chemistry of dynemicin A model systems. Triggering the dynemicin cascade with base or acid (Nicolaou et al.).

While obviously natural enediynes 2-4 behave in the same way, in dynemicin the cascade of events is different. However, this molecule also displays a delivery unit (the anthraquinone), a safety catch (the epoxide) and a trigger (the quinone). Bioreduction of the quinone unleashes two lone pairs (one on the nitrogen and one on the upper hydroquinone oxygen) which bring about intramolecular epoxide opening. ... 

Nicolaou, K.C. Dai, W.-M. Wendebom. S.V. Smith. A.L. Torisawa, Y. Maligres, P. Hwang, C.-K. Enediyne compounds equipped with acid-, base, and photo-sensitive triggering devices. Chemical simulation of the dynemicin A reaction cascade. Angew. Chem., Int. Ed. Engl. 1991. 30. 1032-1036. 

The second activation cascade indicated in Scheme 7-70 for the Nicolaou dynemicin model systems was demonstrated through the triggering of the phenol derivative 352, cleanly produced by photolytic deprotection of the o-nitrobenzyl ether 351 (Scheme 7-74) (119, 120]. Tlreatment of 352 with nucleoplules (e.g., EtOH, EtSH, -PrNH2) provided the aromatization... 

Scheme 7-74 Photoinduced simulation of the dynemicin A cascade. Evidence for a quinone methide intermediate (Nicolaou et al.). NBn, o-nitrobenzyl.

---