Fragmentations, cerium ammonium nitrate

The radical cation fragmentation involves assistance by cerium ammonium nitrate (0.15 mM), the photochemical precursor of the oxidant used in this case, the nitrato radical. 

As it appears from Table 4.2, CC bond fragmentation is a very fast process with electrofugal groups such as disubstituted a-alkoxy cation or (substituted) a,a-dialkoxy cations, and the CSi bond cleaves very quickly. CH bond cleavage is a much slower process, in the cases discussed occurring only as a nucleophile-assisted (in this case by cerium ammonium nitrate) process. Notice that the data refer to... 

Diethylamino)sulfur trifluoride, 110 Formylation (see also Carbonylation) Vilsmeier reagent, 341 Fragmentation reactions Cerium(IV) ammonium nitrate, 67 Copper(II) acetate-Iron(II) sulfate, 85 Lead tetraacetate, 155 Friedel-Crafts alkylation Aluminum chloride, 15... 

Products of oxidation of sulfides by chemical electron transfer (CET) with cerium (IV) ammonium nitrate and photoinduced electron transfer (PET) with C(N02)4 depend on the nature of the sulfide. CET led to fragmentation and a-deprotonation products, whereas PET gave mainly sulfoxides, although in some cases fragmentation was also observed.256... 

Orthoesters can be used for the synthesis of condensed 1,2,4-triazines, provided the appropriate N-N-C-C-N fragment with terminal amino groups is donated by another reactant. For instance, l-amino-5-arylaminomethyl-l,2,3-triazoles 283 were shown to react with triethyl orthoformate to give the intermediate dihydro compounds 284, which can be oxidized with cerium(iv) ammonium nitrate into the corresponding triazolo-[5,iy][l,2,4]-triazine 285. It is worth noting that aromatization of 284 is accompanied by elimination of the iV-aryl group (Scheme 170) <1996JHC599>. 

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