Aromatic photochemical reactions metal-catalyzed reaction

Perfluoroalkanes are much less reactive but the classic 1959 work by Tadow in Nature attracted attention by showing that partial reduction to give definite products could occur (equation 26). In this work, perfiuorodecalin (PFD) was reduced to perfluoronaphthalene (PFN) by NaSAr. Since then, several PFD conversions have been reported with transition metal reagents, either via photochemical or thermal routes. " For example, hot sodium oxalate (465 °C) aromatizes perfiuorodecalin to give perfluorotetralin and perfluoronaphthalene (equation 27). Decomposition of solid sodium oxalate at temperatures above 450 °C involves initial formation of elemental carbon that catalyzes the subsequent decomposition of oxalate, leading to the presence of an induction period in the overall decomposition reaction. Prior incipient decomposition of sodium oxalate to carbon and sodium carbonate is necessary for this reagent to effect aromatization. 

Photochemical cyclohexane carbonylation was found to be co-catalyzed by d transition metal carbonyls, and aromatic ketones and aldehydes [47], The following mechanism has been suggested for this reaction. 

The thermal or photochemical Buchner reactions produce complex mixtures of cycloheptatrienyl esters, and the daunting complexity of the product mixtures was reduced or even eliminated with the advent of transition-metal catalysts, at first copper-based, then in the early 1980s rhodium(II) catalysts, which were developed by the Belgium group led by Noels and Hubert. The rhodium(II)-catalyzed cyclopropanations of aromatics, especially intramolecular cyclopropanations, have enjoyed a certain popularity due to their high regioselectivity and stereoselectivity. Since the intramolecular Buchner reaction is much more widely used in organic synthesis than the intermolecular version, the former is the focus of this review. 

---