Pyridinium Salt Forming Rh(III)-Catalyzed Annulation Reaction of Secondary Allylamines with Internal Alkynes and Its Application to Surface Modification of a Mesoporous Material.

A Rh(III)-catalyzed C-H activation reaction has been developed for the preparation of pyridinium salts from secondary allylamines and internal alkynes. The pyridinium salts formed by this N-annulation reaction have interesting fluorescence properties. This protocol has been applied to the surface modification of mesoporous silica materials to generate functionalized silica that can be used for the detection of nitrobenzene.

Synthesis of Benzoquinolizinium Salts by Rh(III)-Catalyzed Cascade Double N-Annulation Reactions of Allylamines, Diarylacetylenes, and HBF4.

A new cascade double N-annulation method has been developed for the synthesis of benzoquinolizinium salts. The process takes place between allylamines, internal alkynes, and HBF4 in the presence of Rh(III)/Cu(II) complexes and leads to formation of multisubstituted benzoquinolizinium salts. Importantly, the resulting benzoquinolizinium salts serve as fluorescent materials whose emission wavelengths can be tuned by selection of appropriate substituents.