Volume 67 of Advances in Heterocyclic Chemistry commences with an overview of aromatic biheterocycles written by P. J. Steel (University of Canterbury, New Zealand), which covers biheterocycles containing two identical N-, 0-, or S-containing aromatic heterocyclic rings linked by a single bond between these two rings. No previous review has been available on this group of compounds, which is finding increasing importance as chelating ligands and in various aspects of materials chemistry.
The second chapter in this volume, by Stanislav Radl (Prague, Czech Republic), covers 1,2,4-triazoline-3,5-diones, which comprise the most important group of cyclic aza-dicarbonyl derivatives. These compounds, of particular importance as components in cycloadditions, have not been reviewed recently.
Ping Lue and John Greenhill (of Albright and Wilson Americas, Virginia, and of the University of Florida, respectively) contribute a survey of the applications of enaminones in heterocyclic synthesis. This chapter updates a review written 20 years ago on the chemistry of enaminones by John Greenhill and is particularly timely as the majority of the new work has been in heterocyclic synthesis.
The fourth chapter in the present volume is an account of the synthesis of quaternary benzo[c]phenanthridine alkaloids and has been written by Simon Mackay, Otto Meth-Cohn, and Roger Waigh, all of the University of Sunderland, U.K.
The final chapter of Volume 67 has been authored by El Sayed El Ashry (University of Alexandria, Egypt). Professor El Ashry’s subject is the acyclonucleosides. Indeed, this chapter is the first of a trilogy of chapters that will appear in Volumes 67, 68, and 69. The whole subject of acyclonucleosides has been organized so that the present chapter deals with seconucleosides (i.e., with a single-bond disconnection). Part 2, which is planned to appear in Vol. 68, will cover diseco-nucleosides, and Part 3 (Vol. 69) will cover friseco-, tetruseco-, and pentuseco-nucleosides. These compounds are of considerable interest because of the antiviral activity of many of them.