Controlled, Sunlight‐Driven Reversible Cycloaddition of Multiple Singlet Oxygen Molecules to Anthracene‐Containing Trianglimine Macrocycles

Abstract

Controlled release of singlet oxygen is of interest not only to chemists, but also to biologists and medics involved in cancer therapy. Two chiral polyaza macrocyclic compounds and their corresponding endoperoxides have been synthesized. These peroxides exhibit high temperature stability, up to 80 °C. Detailed studies on their structure, including X‐ray analysis as well as NMR, UV‐VIS ECD spectroscopy and theoretical calculations, combined with photochemical measurements indicate that their high stability is related to the arrangement of oxygen atoms in a conformationally stable macrocyclic ring. Despite the change of carbon hybridization from sp2 to sp3 at the 9 and 10 positions of the anthracene units, the macrocyclic skeleton of the obtained compounds does not change its conformation. The obtained endoperoxides can be formed and release singlet oxygen by irradiation with UV light of 365 and 275 nm, respectively. Release of the oxygen does not degrade the macrocyclic structure.

Imine- and Amine-Type Macrocycles Derived from Chiral Diamines and Aromatic Dialdehydes

“…The application of extended rigid linear aromatic dialdehydes leads to expanded triangular [3 + 3] molecules, such as macrocycles 44a-d (Figure 16). In a recent paper [86] Grajewski et al described the synthesis of the extended trianglimine 44a and its amine counterpart, as well as the corresponding endoperoxide derivatives of these macrocycles. The rich family of trianglimines, isotrianglimines, calixsalens and resorcisalens has recently been the subject of an excellent review [8] and will not be discussed in detail.…”