Synthetic Routes to Ninhydrins. Preparation of Ninhydrin, 5-Methoxyninhydrin, and 5-(Methylthio)Ninhydrin

Two syntheses of 5-methoxyninhydrin (2,2-dihydroxy-5-methoxy-1,3-indanedione) are described. One method employs a novel and efficient two step route, which begins with commercially available 6-methoxy-1-indanone. The application of this strategy for the preparation of a new ninhydrin derivative, 5-(methylthio)ninhydrin, and ninhydrin is also presented.