Photochemical reactions as a tool in organic syntheses.

This article represents only a brief glimpse into one of the fascinating aspects of the chemistry of electronically excited molecules. More exhaustive coverage of synthetic applications of photochemical reactions may be found in texts and reviews. We summarize here by noting that classification of reliable photoreactions is possible, but that the most effective application of the classification scheme requires a familiarity with some of the special features of the chemistry of electronically excited states. Thus, knowledge of the properties of singlet and triplet states, the factors which determine photochemical efficiency and reactivity, and the special technical aspects of photochemical procedures such as selective direct and phtosensitized excitation and photoexcitation at low temperatures or solid matrices make photochemistry a useful tool for the construction of organic molecules. It is our hope that the material and flavor of this article will whet the intellectual and experimental appetites of researchers who are concerned with various aspects of the synthesis of oganic molecules.