Florian Gérald Perrin
The chemistry of aromatic triazenes is well known, and has been explored for more than a century.
These compounds have emerged as very useful intermediates, because of their unique reactivity.
This functionality can notably be used to access many other functional groups, and it is present in
certain bioactive compounds. Recently, our laboratory has reported a novel synthesis of triazenes
using nitrous oxide, which allows the synthesis of 1-alkynyltriazenes. These compounds are poorly
known, as their synthesis is not trivial by other routes. This thesis aims to explore the reactivity of
these compounds.
We have shown that the chemical reactivity of 1-alkynyltriazenes parallels what has been observed
for ynamides. The similarity in reactivity of these two classes of compounds is demonstrated by
addition reactions with acids and by cycloaddition reactions with ketenes and tetracyanoethene.
The presence of the reactive triazene groups in the products allowed for subsequent
transformations.
We also studied the reactivity of these substrates in Ru-catalyzed [2+2] cycloadditions. The
triazenes serve as unique vinyl cation surrogates. Under acidic conditions, the triazene functionality
can be replaced by a variety of groups including halides, alkoxides, sulfoxides, amides, arenes and
heteroarenes, providing efficient access to a pool of chiral and achiral polycyclic compounds
The formation of very reactive cations using cyclic alkenenyl triazenes is described in a short study.
It seems that the strained vinyl cation can be formed, but that its high reactivity prevents it to react
selectively with weak nucelophiles.
In the final part of this work, first results of a rhodium-catalyzed reaction with bifunctional boronic
acids are presented. We show that 1-alkynyltriazenes react in the presence of rhodium to form
indene derivatives. The unique reactivity of the triazenes lead to the formation of unexpected
compounds.
Overall, our results suggest that 1-alkynyltriazenes will become valuable reagents in synthetic
organic chemistry.
EPFL2018
