Reactions promoted by [hydroxy(tosyloxy)iodo]benzene in pyrazino[1,2–b]isoquinolines

The hypervalent iodine reagent PhI(OH)OTs (HTIB) promoted oxidative demethylation of 1,4-hydroquinone methyl ethers to give quinones in a quantitative conversion. The efficacy of this reaction, that has been applied to simple arene compounds and to heterocyclic systems, such as 2-isopropoxycarbonyl-7,10-dimethoxy-pyrazino[1,2–b]isoquinoline-4-ones and 1,4-diones to get the corresponding 7,10-quinones (compounds 6–8), is similar to those promoted by CAN and does not require the presence of water. Instead of oxidative demethylation, HTIB promoted in 1-methoxy-pyrazino[1,2–b]isoquinoline-4-ones complex multi-step processes to give compounds 9 or 10.