Amines oxidation with iodosobenzen

Oxidation of cyclic secondary amines such as pyrrolidine (351) and piperidine (353) with iodosobenzene in water leads to lactams 352 and 354, respectively (88TL6913, 88TL6917) (Scheme 90). Similar oxidation of 2-piperidinecarboxylic acid and 2-pyrrolidinecarboxylic acid is accompanied by decarboxylation. Cyclic tertiary amines 355, 357, and 359 (Eq. 48) are likewise oxidized to the corresponding lactams. Other examples include phencyclidine (360) to A-(l-phenylcyclohexyl)piperidone (361), N-(cyanocyclohexyl)piperidine (362) to A-(l-cyanocyclohexyl)piperidone (363) (Scheme 91), and 1,2,3,4-tetrahydroisoquinoline to 1,2,3,4-tetrahy-droisoquinolinone (Eq. 49). 

Like their carbene cousins, the insertion of nitrenes into C-H bonds is a useful method for functionalizing molecules (Scheme 8.148). " The nitrenes are typically generated by the oxidation of an amine derivative in the presence of the metal catalyst, most often, but not exclusively, a rhodium complex. Widely used oxidants are iodosobenzene diacetate and iodosobenzene. These react with the amine derivative to form an... 

The lactam formation from the oxidation of cyclic amines (353, for example) probably proceeds via intermediate 364. The nitrogen-iodine bond dissociates to give imine 365, which reacts again with a second equivalent of iodosobenzene to give another intermediate 366. Finally, 366 on reductive... 

Many chiral rhodium complexes have been studied to perform enantiose-lective intramolecular benzylic C—H amination with sulfamates. Up to now, it is Rh2[(S)-nap]4, recently disclosed by Du Bois and coworkers, that provides the highest enantioselectivities for benzylic C—H amination of sulfamates in the presence of iodosobenzene (Eq. (5.13)) [68]. This catalyst appears to be particularly resistant to the oxidizing reaction conditions. Allylic C—H bond insertions are also possible, although only in moderate yields and ee >80% for Z-alkenes. 

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