Synthesis of 1,2,4-triazines and the triazinoisoquinolinedione DEF ring system of noelaquinone.

The intramolecular Staudinger-aza-Wittig reaction is used for a general synthesis of 1,2,5,6-tetrahydro-1,2,4-triazines, a structural motif reported for the natural product noelaquinone. The DEF moiety of noelaquinone was obtained in 13 steps and 2% overall yield, and the structure of the synthetic product was confirmed by X-ray analysis.