Trapping of Radical Cations by Nucleophiles

Mechanistically, the conversion of acid to ladone is viewed as occurring through the transfer of an eledron from the olefinic moiety of 232 to yield the corresponding radical cation, which then undergoes cydization to give lactone 233. When 1-cyanonaphthalene (1-CN) is used as the sensitizer, both the quantum and product yields were found to be moderate. However, the use of a sterically hindered sensitizer led to an increase of both yields, as well as of the quantum efficiency. 

The generation of nonstabilized azomethine ylide 256 via PET-initiated sequential double desilylation and [3 + 2]-cycloaddition reaction with various dipolarophiles to generate five-membered heterocycles 257, has also been established by Pandey et al., as shown in Table 8.5 [110]. 

The authors gratefully acknowledge the diligent and dedicated collaboration of all their colleagues whose names appear as coauthors in the references. Thanks are also due to Mr K. C. Bharadwaj, Mr Balakrishnan, and Mr K. N. Tiwari for their assistance in the 

1 Wilson, J.E. and Fu, G.C. (2006) Synthesis of functionalized cyclopentenes through catalytic asymmetric [3 + 2] cycloadditions of allenes with enones. Angewandte Chemie, International Edition, 45, 1426-1429. 

3 Beilina, F. and Rossi, R. (2006) Synthesis and biological activity of pyrrole, pyrroline and pyrrolidine derivatives with two aryl groups on adjacent positions. Tetrahedron, 62, 7213-7256. 

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