Metal catalyzed azide ring

For example, oiganoimido complexes of Group VI transition metals have been shown to catalyze the ring cleavage of styrene oxide (48) by trimethylsilyl azide. The observed regio-... 

A drawback of the copper(l)-catalyzed variant of this reaction is the presence of the transition metal, which is potentially toxic for hving cells. Therefore, ring-strained cyclooctyne derivatives have been introduced as substrates for the azide-alkyne cycloaddition whose reaction with the azide does not require a transition metal catalyst (Figure 16). The driving force of the corresponding copper-free click reaction stems for the release of ring strain associated with the conversion of the cyclooctyne s triple bond into a double bond. Fluorine substituents make the system even more reactive. ... 

A sizable number of reports describe carbocationic chemistry initiated by transition metal catalysts. This includes a variety of cyclization and ring-opening transformations. For example, a Rh2(II)-catalyzed synthetic method has been developed as a means of preparing 2,3-disubstituted indoles from styryl azides (Scheme 30)7 The chemistry... 

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