Friedel-Crafts reaction, photochemical alternative

The Friedel-Crafts reaction, a widely used reaction in both industrial and academic laboratories, produces several byproducts which must be handled as pollutants. An alternative which involves the photochemically-mediated reaction of an aldehyde with a quinone is described. This alternative chemistry can be applied to direct syntheses of the ring systems of the benzodiazepines and benzoxepins. 

KRAUS ET AL. A Photochemical Alternative to Friedel—Crafts Reaction 77... 

The benzophenone shown above has already been synthesized using our photochemical alternative to the Friedel-Crafts reaction. It was prepared by the reaction of benzoquinone and benzaldehyde and has been prepared on a 30 gram scale. 

From 1992, Kraus and co-workers explored the synthetic value of the photochemical acylation of 1,4-quinones (Scheme 32 Table 88.11), and developed it as a suitable alternative to existing thermal Friedel-Crafts acylations.During their studies on the pyranoquinone skeleton, they initially used the classical Friedel-Crafts approach but the poor solubUity of some of the starting materials, the drastic reaction... 

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