Although many o-QDM precursors are kn~ wn~,~ J~ they all suffer from the problem that they are difficult to prepare, especially with a variety of substituents. One of the simplest methods for preparing o-QDM's involves the photolysis of o-methylbenzaldehyde or its derivatives to promote intramolecular H-atom abstraction (Scheme I). 3 While the starting materials are readily available and the reaction is simple, there are problems if the dienophile, added to ...
