Singlet Oxygen in Organic Chemistry

Because of its elusive nature and transient lifetime, the existence of singlet oxygen took nearly a century to be accepted by the chemistry community. This time period also witnessed ongoing debate and sharp differences in the interpretation of experimental results. However, by the early 1970’s all resistance to the reality of singlet oxygen was replaced with growing interest and excitement in harnessing this new and unique reagent. Singlet oxygen physics and generation are first covered, followed by its application to organic chemistry. Special emphasis is placed on reviewing the role of singlet oxygen in organic synthesis including the ene reaction as well as both the [2 + 2] and [4 + 2] cycloadditions with recent literature examples.