Untersuchungen an 1,4-Naphthochinonen, 19. Mitt.: 2-, 3- und 6-Methyljuglon aus Formylnaphtholen

1,4-Naphthoquinones, XIX: 2-, 3- and 6-Methyljuglone from Formylnaphthol Derivatives The methylnaphthol derivatives 9 and 10 are suitable compounds for the synthesis of plumbagin, 6-methyljuglone ( 14 ) and 3-methylnaphthazarine ( 12 ). 9 and 10 are derived from 5 and 6 which are synthesized by formylation of the naphthols 2 and 3 . As it was not possible to get the formylnaphthol 8 in the same way, isoplumbagin ( 18 ) was prepared by bromine-lithium exchange in the key compound 16 followed by methylation and oxidation.