A Survey on the Reactivity of Phenyliodonium Ylide of 2-Hydroxy-1,4-Naphthoquinone with Amino Compounds

The phenyliodonium ylide of 2-hydroxy-1,4-naphthoquinone reacts with aminoesters, ureas, aminoalcohols and aminophenols in refluxing dichloromethane to afford good yields of indanedione 2-carboxamido compounds, that in solution exist in an enol-amide form. The same reactants in a copper-catalyzed reaction afford mainly the corresponding N-arylo compounds. Arylhydrazines are mainly oxidized by the ylide and arylation occurs only in a low yield

Cycloaddition Reactions of Indanedioneketene with Electron-Rich Dienophiles: An Experimental and a Theoretical Study

Thermal decomposition of the phenyliodonium ylide of lawsone gives rise to a highly reactive cyclic α,α′-dioxoketene, indanedioneketene, which reacts with electron-rich dienophiles such as enol ethers to afford [4 + 2] cycloadducts. The initially formed 2,3-dihydro-2-alkoxy-indeno­[1,2-<i>b</i>]­pyrano-4,5-diones are labile compounds since through an opening of the pyranone ring upon heating they easily tautomerize to alkoxyallylidene-indenedione derivatives and under acid-catalysis they are additionally transformed to 2-(1,3-dihydroxyallylidene)-1<i>H</i>-indene-1,3­(2<i>H</i>)-dione or by loss of alcohol to indeno­[1,2-<i>b</i>]­pyran-4,5-diones. A DFT study explains the polar nature of the cycloaddition reaction, the observed reactivity and suggests a possible mechanism operating in these reactions