Ebenaceae extractives. Part 7. Use of hydroxy-proton shifts of juglone derivatives in structure elucidation

Abstract

Substitution at one or more positions of Juglone by bromo-, chloro-, hydroxy-, and methyl groups causes changes in the chemical shift of the hydroxy-proton which are additive and depend only on the nature and positions of the substituents. The hydroxy-proton signals of natural Juglone derivatives show similar regularities and enable the structures of neodiospyrin (11), galpinone (8), and bisisodiospyrin (7) to be defined.