Reactivity of Indanedioneketene Dimer with Amines

The highly reactive indanedioneketene 5, resulting from the thermal decomposition of phenyliodonium ylide of 2-hydroxy-1,4-naphthoquinone (lawsone, 4), in the absence of nucleophiles dimerizes to the corresponding tetraoxo spiro oxetanone 6 in quantitative yield. This oxetanone exhibits an interesting reactivity toward amines.