Dedicated to Dr. Alfred Bader on the occasion of his 93rd birthday and in memory of Oxana Bennett
A domino reaction has been used for the construction of lactonamycin derivatives.
This research led to a comparison study between palladium-mediated cascade cyclisations
and thermal alkyne [2+2+2] cyclisations. A palladium-mediated cyclisation of alkenyl
bromides with alkynes and furans has been shown to furnish highly substituted aromatic
rings. Penta- and hexasubstituted aromatic rings have also been prepared by the thermolysis
of suitably substituted alkynes under microwave conditions. Tetrasubstituted pyridines
can also be prepared using nitriles instead of alkynes. This work will provide a new
and interesting array of drug templates; mechanistic details are discussed for both
reaction series.
Key words
alkynes - aromatic rings - cyclisation - thermolysis - palladium