Manganese-containing heterocycles

When acetylthiophenes are subjected to orthomanganation, formation of the 2,3-, 103, and 3,4-, 104, metallocycles is observed [88JOM(349)197]. Complex 103 contains two coplanar live-membered heterocycles with octahedral manganese. Complex 104 is also planar. In both cases, substantial delocalization of the TT-electron density follows from the structural parameters. 

As shown in the manganese- and ruthenium-catalyzed intermolecular nitrene insertions, most of these results supposed the transfer of a nitrene group from iminoiodanes of formula PhI=NR to substrates that contain a somewhat activated carbon-hydrogen bond (Scheme 14). Allylic or benzylic C-H bonds, C-H bonds a to oxygen, and very recently, Q spz)-Y bonds of heterocycles have been the preferred reaction sites for the above catalytic systems, whereas very few examples of the tosylamidation of unactivated C-H bonds have been reported to date. 

The compounds in this section can be divided into two categories those in which the heterocyclic group is a substituent on the metallocene, such as heterocyclic compounds containing cyclopentadienyl-manganese tricarbonyl, and those in which a heteroatom is in a ring of the metallocene, such as in azaferrocene. 

Dehydrogenations are very easy in six-membered nitrogen-containing compounds that already contain one or two double bonds in the heterocyclic ring. Such dehydrogenations are carried out by nitric acid [455], arsenic oxide (AsjOj) [480], manganese dioxide [825], potassium ferricyanide [919], nitrobenzene, and others (equations 41 and 42). 

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