Applications of Di-π-Methane and Related Rearrangement Reactions in Chemical Synthesis

The di-π-methane (DPM) rearrangement reaction is one of the most studied photochemical transformations. The oxa-di-π-methane (ODPM) rearrangement reaction has been recognized as a powerful synthetic protocol and one that can be applied to both cyclic and acyclic substrates. In the case of aza-di-π-methane (ADPM) rearrangement reactions involving 1-aza-1,4-dienes, regioselective conversions have been observed. The DPM reaction usually takes place through a singlet pathway (S1) in the excited state when acyclic 1,4-dienes are involved. The DPM rearrangement reaction requires a substrate incorporating two olefinic residues (π-systems) linked to a common sp3-hybridized carbon or, in other words, a 1,4-diene. A range of methods is available for the synthesis of the acyclic 1,4-dienes required as substrates for the DPM rearrangement reaction, and some of these are also summarized in the chapter.