Wagner-Meerwein rearrangement photochemical

Heathcock used as concerted cycloaddition intramolecular photochemical (2 + 2) addition to create the quaternary center in his projected synthesis. A cationic rearrangement Wagner-Meerwein rearrangement) was intended as further key step but failed (162). 

Cristol, S. J., Opitz, R. J. Photochemical transformations. 40. syn and anti Migration in photo-Wagner-Meerwein rearrangements. J. Org. Chem. 1985, 50, 4558-4563. 

Pyrene and 4-methyl- and 4,5-dimethyl-pyrene have been prepared from 4//-cyclopenta[de/]phenanthrenes by a reaction sequence involving carbox-ylation and then conversion, through the ester, into the carbinol, which undergoes Wagner-Meerwein rearrangement. 5,12-Diphenylnaphthacene undergoes photochemical oxidation,giving a mixture of endoperoxides (397) and (398) the major product, (397), was subsequently converted into the diol (399). 

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