Excised aromatization

Excision repair. The E. coli mismatch repair is a type of excision repair. However, a different nucleotide excision repair system (NER) is utilized by all organisms from bacteria to human to remove a variety of defects. These include thymine dimers, photohydrates, oxidized bases, adducts of cisplatin (Box 5-B), mutagens derived from polycyclic aromatic compounds,683 and poorly recognized OC mismatched pairs.692 In E. coli this excision repair process depends upon proteins encoded by genes UvrA, B, C, and D and also DNA polymerase I and DNA ligase.693 695a A dimer of protein UvrA forms a complex with helicase UvrB (Eq. 27-22).696 696a... 

In Chapter 2, Matsuo and Nakamura describe the synthetic developments of a subgroup of bowl-shaped it-conjugated corannulenes and expand the topic to the discussion of the synthesis of a novel class of organic fluorophores derived from C60, hoop-shaped condensed aromatic compounds. They are made by selective removal of ten sp2 carbon centers out of conjugation from the north and south pole regions of C60. The resulting 40-jr-electron [lOjcyclophenacenes excised... 

A new development in the area of alternative diesel fuels is a fuel produced from vegetable oils and animal fats using specially modified hydrogenation processes in a conventional petroleum processing facility (Rantanen et al., 2005). This fuel retains the low sulfur and low aromatic character of biodiesel but contains no oxygen and has a heating value that is similar to petroleum diesel fuel. Recent U.S. interest in this approach has expanded due to governmental announcements that the fuel qualifies for federal excise tax credits. 

Although the aromatic moiety itself is stable in the presence of chromic acid, the benzylic position is particularly susceptible to oxidation. Notice that the alkyl group is entirely excised, leaving only the benzylic carbon atom behind. The product is benzoic acid, irrespective of the identity of the alkyl group. The only condition is that the benzylic position must have at least one proton. If the benzylic position lacks a proton, then oxidation does not occur. 

---