Study 6.23 Organic synthesis Diels Alder trapping of photoenols

Case Study 6.23 Organic synthesis - Diels-Alder trapping of photoenols 

The total synthesis of cytotoxic agents hamigerans was achieved via the photoenoliza-tion of substituted benzaldehydes and the subsequent Diels Alder (dark) reaction.983 Two species, E- and Z-isomers of 305, while being interconverted by E Z 

Case Study 6.24 Photoremovable protecting groups - 2,5-dimethyl-phenacyl chromophore 

For example,3n,7t excited 1,4-benzoquinone affords spiro-oxetanes in the presence of alkenes exclusively, whereas 1,4-naphthoquinone, in which the energies of the 3n,Jt and 37t,7t states are close, produces both spiro-oxetanes and cyclobutanes.990 Introduction of electron-donor substituents on quinones further destabilizes the 3n,Jt state. 

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