Oxidation of 1-Naphthols by Lead Tetraacetate in Acetic Acid

Abstract

A detailed study of the lead tetraacetate-acetic acid oxidation of 1-naphthol , 4-acetoxy-1-naphthol, 2-methyl-1-naphthol, 2,3-dimethyl-1- naphthol and 1,2,3,4-tetrahydro-9-anthrol (17) has been carried out. In the case of 1-naphthol the major product was 4-acetoxy-1-naphthol (4), with 2,2-diacetoxynaphthalen-1(2H)-one (2) being the only other product formed in significant yield. Attack at C4 was again the main reaction with 4-acetoxy-1-naphthol, which gave 1,4-naphthoquinone as the major product. Acetoxylation occurred predominantly at C2 with 2-methyl-1-naphthol and 2,3-dimethyl-1-naphthol to give the naphthalen-1(2H)-ones (11) and (12) respectively. In both cases minor amounts of 4- acetoxylated derivatives and quinones were also produced. 1,2,3,4- Tetrahydro-9-anthrol (17) gave an analogous set of products, the yields of which showed an unusual concentration dependence. In dilute solution 10-acetoxy-1,2,3,4-tetrahydro-9-anthrol(19) was produced in high yield, whereas with a high substrate concentration a good yield of 9a-acetoxy- 1,2,3,4-tetrahydroanthracen-9(9aH)-one (18) was obtained.