Description:(from preface)Life begins at 40! Certainly for Advances in Heterocyclic Chemistry the fortieth volume marks some rather far-reaching changes in the series. These changes are described in detail in the introductory chapter ''Advances in Heterocyclic Chemistry: Prospect and Retrospect'' by your editor and Carol Drum, but it is appropriate to highlight the most important innovations in this preface. First, we have addressed the long-standing problem of indexing. Volume 40 contains a subject index for all the 40 regular volumes of the series together with the two supplementary volumes. Additionally, we have instituted an index of names of the contributors of chapters for our series, again spanning the whole 42 volumes. We have also completely revised the existing index of chapter titles. In the future, these three indexes will appear every five volumes; thus the next ''index volume'' will be 45. We believe that this procedure will provide the maximum benefit to readers of the series, while avoiding undue repetition...