Description:(from preface)The present volume consists of five chapters, three of which are on subjects previously covered in these advances.The photochemistry o( oxygen- and sulfur-containing heterocycles is complementary to the review on the photochemistry oi' nitrogen heterocycles that appeared in Volume 30: together these two chapters update an earlier review of the photochemistry of heterocycles (all by S. T. Reid). which appeared in 1970 in Volume II. Paudler and Sheets have updated their review of the general chemistry o( naphthyridines, which also appeared in Volume II. In addition, van der Plas. Wo/niak. and van den Haak have specifically considered the reactions of naphthyridines with nitrogen nueleophiles. largely from their own extensive investigations in this area.Hermecv and Mes/aros have surveyed the chemistry of pyrido| l.2-