Introduction by Prof. Gerhard Maas (Volume Editor):

This volume covers the synthesis of three- and four-membered heterocycles with maximum unsaturation and of five-membered hetarenes with one oxygen, sulfur, selenium, tellurium, nitrogen, or phosphorus atom. Maximum unsaturation means that the ring doesn't contain either a sp3-hybridized carbon atom or a heteroatom incapable of π-conjugation. Some compounds which are derivatives of such ring systems but no longer feature maximum unsaturation are also included, namely thiirene 1,1-dioxides, thiophene 1,1-dioxides, and l 5-phosphirenes or h1-metal complexes of l 3-phosphirenes.

This volume deviates from the common principle of the series to treat benzo-annulated systems directly after the monocyclic ring systems. While this rule is observed where relevant for the three- and four-membered ring systems, annulated systems such as benzofurans, benzothiophenes, benzopyrroles (indoles) etc. are covered separately in Volume 10 (Fused Five-Membered Hetarenes with One Heteroatom). This was done because the three- and four-membered ring systems alone would not have filled one volume, and the material for monocyclic and benzo-annulated five-membered hetarenes is much too abundant for one volume.

The ring systems covered in this volume occupy a wide range of stabilities and reactivities. They can have a fleeting existence such as the antiaromatic three-membered rings of oxirene, thiirene, selenirene, and 1H-azirine, be highly reactive such as the kinetically stabilized, formally antiaromatic tri-tert-butylazete, or represent basic chemicals in their parent form, such as furan, pyrrole, and thiophene, which are tolerant to a broad range of reaction conditions during their synthesis and selective transformation. Also, the various ring systems described in this volume were introduced to the field of chemical science at well-spaced intervals over the last 200 years. Since the chemistry of the five-membered hetarenes furan, pyrrole, and thiophene had the longest time to mature, it is clear that the chapters on these three classes of ring systems are by far the largest ones in this volume.

The decision to create a series of volumes on Organometallics was based on an appreciation of the increasing role that metal complexes play as reagents in organic synthesis. In addition organometallic complexes are widely used as catalysts or precatalysts in many organic transformations and so their importance is increasing dramatically over the past quarter century.

The links below provide further information about Volume 9

• Detailed table of contents (pdf).
• List of authors.