Azaanthraquinone alkaloids

Pummerer reaction conditions was followed by cycUzation to isomilnchnone 292 and hence to cycloadduct 293, which loses water to form a-pyridone 294. Subsequent manipulation involving deoxygenation and debenzylation completed the synthesis. In similar fashion, the azaanthraquinone alkaloid dielsiquinone was synthesized for the first time. Also, the quinolizidine alkaloids ( )-lupinine and ( )-anagyrine, and the ergot alkaloid ( )-costaclavine were synthesized using this Pummerer cyclization-cycloaddition cascade of imidosulfoxides and isomiinch-nones. 

Choshi, T., Kumemura, T., Nobuhiro, J., and Hibino, S. 2008. Novel synthesis of the 2-azaanthraquinone alkaloid, scorpinone, based on two microwave-assisted pericyclic reactions. Tetrahedron Letters, 49 3725-28. 

Choshi et al. (2008) have developed a novel method for the total synthesis of the 2-azaanthraquinone alkaloid in nine steps, out of which, one key step involves a microwave-assisted [4+2] cycloaddition reaction for the constriction of a 2-azaanthraquinone frame work. 

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