Preface [Hot Topic: Heterocyclic Chemistry (Guest Editor: Jan Bergman)]

The chemistry of heterocyclic betaines, which include several alkaloids like orellanine, is surveyed by Dr A. Schmidt, Technical University of Clausthal, Germany. Heterocycles based on ephedrines have been extensively used in the field of asymmetric synthesis. The chemistry involved is now thoroughly reviewed by Drs A. Cruz and M. Juarez-Juares. 1,3-Diketones have been frequently used for the synthesis of 4,5,6,7-tetrahydro-indoles but also for a large number of other heterocycles. The whole area has now been comprehensively reviewed by a group of authors, including Prof. Viktor Milata, from the Slovak Republic. In the last chapter Prof. R. Lavilla from the University of Barcelona, Spain is discussing the non-conventional redox chemistry of dihydropyridines and how this class of molecules can be used for the preparation of otherwise inaccessible heterocycles.