Generation and Trapping of Pyridine o-Quinodimethanes and Their Functional Analogues: Synthesis of Heterolignans and Conformationally Restricted Analogues of Nicotine

Since Cava’s pioneering work on the generation of the very reactive species oquinodimethane 1, studies have continued unabated on the modes of preparation, physical properties, and synthetic applications of 1 and its derivatives. Several review articles published during the past few decades amply bear this out. On the other hand, the heteroaromatic analogues 2 have received much less attention, although this situation is rapidly changing in recent years. In the background of this development, it is surprising that not much systematic work has been done on functional analogues of 2, e.g. 3 (X = O), which are good candidates for both inter- and intramolecular Diels- Alder reactions leading to an array of heterocyclic ring systems related to natural and non-natural products of biological significance