Preface

Four of the reviews in the present volume survey complete topics: the tellurophenes (Fringuelli. Marino, and Taticchi), the 1.2-dioxetanes (Adam), the thienopyridines (Barker), and the isoxazolidines (Takeuchi and Furusaki). The first two fields are relatively new with little of signifi- cance reported before the present decade, and while the other two have a longer history, neither has previously been completely reviewed.

Two other chapters, one covering the tetrazoles (including fused tetrazoles) (Butler), and one entitled “Pyrrolodiazines with a Bridgehead Nitrogen” (i.e., the pyrrolol I ,2 I-pyridazines, -pyrimidines, and -pyra- zines) (Kuhla and Lombardino), update fields which have been reviewed elsewhere. Another. by Filler and Rao, surveys development in the oxazolone field since i t was reviewed in this Series eleven years ago.

The remaining chapter, by Reinhoudt, deals with (2 t 2)-cycloaddition and (2 + 2)-cycloreversions. This chapter, concerned with the formation and rupture of membered heterocycles, is structured as to reaction type rather than heterocyclic ring.

A. J. BO~JLTON A. R. KATRITZKY