Intermolecular Amination with Phenanthroline Ligands

TABLE 6.2. Intramolecular C-H Amidation by Silver-Terpyridine Catalyst 

More importantly, this silver system catalyzes the intermolecular amination of hydrocarbons, as shown in Table 6.3. In addition to animating weaker benzylic C-H bonds, stronger aliphatic C-H bonds such as those in cyclohexane were also reactive. Although yields with more inert hydrocarbons were modest with the bathophenan-throline system, the discovery of the first silver-catalyzed intermolecular amination opens opportunities for further developments. This reaction favored tertiary cyclic sp3 C-H bonds over secondary cyclic sp3 C-H bonds, and showed limited success with simple linear alkanes. No conversion was observed with any aromatic C-H bonds. The compound NsNH2 was tested as the nitrene precursor with different oxidants. The use of PhI(OAc)2 as oxidant gave the expected amination product with a lower yield, while persulfate and peroxides showed no reactivity. 

Similar to that of the Bu jtpy-silver catalyst, the crystal structure of the bath-ophenanthroline-silver complex has a disilver(I) core and two BP ligands stacked over each other, similar to the corresponding palladium(II)-BP complex. 

TABLE 6.3. Silver-Bathophenanthroline Catalysis of a Mild Intermolecular C-H Amination 

The development of new phenanthroline ligands with electron-withdrawing modifications on the 4 and 7 positions may be a way to enhance the reactivity further. 

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