Trimethyl phosphine, irradiation

The quinoline-2-one was then converted into the required 1-methyl-(o-azidophenyl)-quinoline-2-one via known synthetic manipulations. Cyclization of this intermediate to the target Cryptotackieine was performed under microwave irradiation at 180 °C for 30 min, in the presence of trimethyl phosphine. It is noteworthy that the same aza-Wittig reaction, when carried out under classical heating for 24 h, furnished inferior yields. The quinolin-2-one intermediate, when heated at 150 °C in o-xylene under conventional heating conditions, underwent a nitrene insertion at the C-4 position of the pyridinone ring. Subsequent Red-AI reduction of the carbonyl group furnished the Cryptosanguinolentine. 

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