Photo-Oxidation of 2-Methylamino-3-(1-piperidinylmethyl)-1,4-naphthoquinone.

2-Methylamino-3-(1-piperidinylmethyl)-1, 4-naphthoquinone (7) was prepared via several steps from 2-methyl-1, 4-naphthoquinone (vitamin K3, 3). The quinone (7) was photochemically oxidized to 2-methylamino-3-(1-piperidinylcarbonyl)-1, 4-naphthoquinone (8) and/or 2-alkoxycarbonyl-3-methylamino-1, 4-naphthoquinone (9), depending on the solvent used.