Phosgene-Free Synthesis of Verdazyl Radicals and Enantioselective 1,3-Dipolar Cycloaddition Reactions of Azomethine Imines Generated in situ from Verdazyl Radicals.

摘要

Verdazyl radicals started receiving attention as substrates for organic synthesis only a few years ago. Since then, the chemistry of verdazyl radicals has advanced at a very fast rate. There are now a number of generations of novel molecular scaffolds derived from verdazyl radicals. Traditionally, verdazyl radicals have been synthesized from mono-substituted alkyl hydrazine and phosgene, which are extremely dangerous to handle. Alkyl hydrazines are restricted from being imported into certain countries, including Canada. A completely new alkyl hydrazine- and phosgene-free synthesis is reported in this thesis. The new synthesis, relative to previously reported syntheses of verdazyl radicals, is safer, more economical and provides the ability to derivatize verdazyl radicals to a larger extent. In addition, enantioselective 1,3-dipolar cycloaddition reactions with various metal- or organo-catalysts are reported. The project is still in progress with the highest e.e. of > 90%.