A novel hetero Diels - Alder reaction as a route to annelated pyridines and bipyridines

A novel hetero Diels - Alder reaction has been developed to facilitate the synthesis of annelated pyridines as models for pyridoacridine alkaloids. The key reaction is based on an intramolecular Diels - Alder reaction of an aza - 1,3-butadiene with an appropriate dienophile, to yield the desired annelated pyridine. An extension of this methodology is to exploit the Eglinton copper (IT) dimerisation of terminal acetylenes. This allows for a unique double intramolecular hetero Diels - Alder reaction, where four new rings are formed in one step. This allows for a facile route to annelated bipyridines. Ultimately this methodology has led to an approach to the total synthesis of the natural product eilatin, a member of the class of compounds known as pyridoacridines.