Redox-photosensitized chain monomerization of cis-syn-dimer of dimethylthymine; unusual effect of molecular oxygen

✍ Scribed by Tetsuro Majima; Chyongjin Pac; Junichi Kubo; Hiroshi Sakurai

• Book ID: 104237209
• Publisher: Elsevier Science
• Year: 1980
• Tongue: French
• Weight: 222 KB
• Volume: 21
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(01)85478-2

✦ Synopsis

Photosensitized monomerization of thymine dimers is of biological interest with regard to enzymatic photoreactivation (PR) of damaged DNA and has been investigated for understanding of unknown molecular mechanisms of PR. 2-4 Even in typical photosensitized reactions, however, quantum yields for the monomerization are usually low, 2'3 0.5 at best.l Since PR is thought to be very efficient, 5 model reactions should meet, at least, the requirement that efficiencies be high. We have found that cis,ss-dimethylthymine cyclobutane dimer (DMTODMT) is efficiently monomerized by the redox-photosensitization using aromatic hydrocarbon (S)-pdicyanobenzene(DCNB)-acetonitrile systems6" and that oxygen molecules remarkably enhance efficiencies of the photosensitized monomerization. Ids-DCNB 2 CH3CN DMTODMT Irradiation of an air-saturated dry acetonitrile solution containing phenanthrene, DCNB, and DMTODMT at 313 run gave N,N '-dimethylthymine (DMT) in nearly